The Steps Involved In Wastewater Treatment Environmental Sciences Essay

The Steps Involved In Wastewater Treatment Environmental Sciences Essay The aim of this report is to explain clearly in detail the steps involved in wastewater treatment including the disadvantages and suggested improvements to the process. This report will take on an engineering analysis of the many complex processes and the steps involved in processing wastewater into clean water safe to be discharged into the environment. Also included in this report is an overall process diagram of the wastewater treatment. Furthermore, the limitations and key advantages of this treatment are outlined and the appropriate and suitable improvements that can be made to overcome them are explored. Introduction Water, one of the worlds most important but unfortunately finite source, which is being endlessly used and reused. Wastewater treatment is the process in which wastewater as well as the sewage, is filled with bacteria, chemicals and other contaminants is cleaned so that it can be recycled back safe for use. Once the treatment is complete, all forms of solids called sludge, regardless of the shape and size that was present in the wastewater will be removed. Besides that, oxygen gets restored into the water, which then eventually ends up in the lakes and rivers which require oxygen rich water to support the lifestyle of the aquatic organisms. Wastewater includes a combination of domestic sewage (toilets, kitchen, and laundry) on a smaller scale and on a larger scale this consists of industrial effluent, schools as well as businesses (chemical and wastes, hospitals, shopping centres). Wastewater is also obtained from storm water infiltration and ground water which enters the sewer through the cracks present. Generally the waste can be broken down naturally with bacteria and other biological organisms especially when it is just household or business waste. However, wastes obtained from industries are generally toxic and require a physical/chemical treatment plant, which uses both chemical reactions and physical processes to process the wastewater. Overview of the treatment: As an overview, the wastewater treatment occurs in three stages which will be discussed thoroughly. It begins with the preliminary and primary treatment where 40-60 % of the solids are removed (City of Columbia). Followed by the secondary treatment where 90% of the pollutants are removed, hence completing the liquid portion process (City of Columbia). The next step would be the treatment and removal of the sludge (bio-solids). The number of stages of the treatment varies but generally go up to four depending on the quality of water being treated. Below is a picture of an aerial view of a general wastewater treatment plant. Source: http://www.waterencyclopedia.com/Tw-Z/Wastewater-Treatment-and-Management.html , 2010 Below, is the overall process diagram of the wastewater treatment. (Source: Wastewater treatment and principals and regulations brochure) Preliminary Treatment The preliminary treatment is the first stage in wastewater treatment with its main purpose removing coarse solids and large materials found in raw water to make the water suitable for the main treatment process. It also ensures that the pumping equipment does not get damaged. This initial stage involves various different processes which include screening, grit removal and odour control. Initially, the sewage is screened to remove large objects which include plastics and paper. This step is crucial to make sure that there is no blockage in the pipe system as well as no damages to the equipment. This is done generally by passing the sewage through mechanically raked bar screens (consisting of vertical bars spaced close together) which are used to capture the large objects and remove them from the wastewater stream. The screenings (material which have been cleared in this step) is disposed safely at a landfill site. Below is an example of a raked screen bar image used in industries. (Source : Huber Technology, 2009) The next step is the grit removal which includes grit, stones and dirt. However, before the sewage enters the grit tanks, Ferrous Chloride (FeCl2) and lime are added to improve the subsequent chemical treatment. Ferrous Chloride precipitates phosphorus thus reducing the growth of toxic algae in the water. Lime on the other hand is added to increase the pH level which aids the Ferrous Chloride in removing phosphorus and other material from the sewage. Various different types of detritus tanks, grinders and cyclonic inertial separation are used including a comminutor and grit chamber to remove the coarse solids. A comminutor is actually a grinding pump which houses a rotating cutting screen that makes shreds large organic matter, therefore making it easier for microorganisms to decompose the organic matter. This step also further prevents any damage to the machines and pumps in the process. The effectiveness of the chemicals added prior in the grit chamber is improved by adding and mixing compressed air into the wastewater. In order to allow the heavier inorganic materials settle out of the waste stream, the velocity of the incoming sewage is controlled. The air flow is also adjusted to create velocity near the bottom part of the chamber to catch the grit in a current hence, allowing it to settle. Chlorination is another step that could be used in the preliminary treatment. However, as chlorination can be used for all the different stages in the treatment, the equipment has to be design specially and carefully for the same operations. All the disposals collected from the preliminary stages are disposed of safely in a landfill. Primary Treatment The next step, following the preliminary treatment is the primary treatment. The purpose of this step is to remove the particles which are able to settle by sedimentation which includes organic nitrogen, organic phosphorous and heavy metals (New York Water operations 2007). This is done by passing the wastewater through the primary sedimentation tanks or primary clarifiers where solid particles are removed by physical settling due to its density, buoyancy and the force of gravity. Coagulants and flocculants such as solid and liquid Aluminium Sulphate and Aluminium Hydroxide Chloride (Accepta Water Treatment, 2010) are often added to expedite this process by encouraging the aggregation of particles. However, the pH level has to be constantly adjusted as they tend to reduce the pH levels of the wastewater. (Source : City of Camarillo, 2010) Above is an image of a sedimentation tank. They are designed to hold wastewater for numerous hours by then which most of the heavy solids would settle at the bottom of the tank. They would then form thick slurry known as sludge and also floating material such as fats, oil and grease to rise to the surface which would then be skimmed off. There are mechanical scrapers that have been designed for the tanks with the purpose of collecting the sludge at the bottom and the scum floating on the top. Both the sludge and skimmed material are generally pumped to a solid treatment process. The sedimentation process is basically mainly to produce a liquid which is able to be treated biologically by reducing the biological oxygen demand, also known as BOD of water. BOD is the quantity of oxygen that is needed by aerobic microorganisms to decompose organic matter in a sample of water. The degree of water pollution can also be measured by the BOD. (The American Heritage ® Dictionary of the English Language) When the solids are removed at these early stages, BOD can be reduced by 30-40 percent hence, increasing the efficiency of microbial digestion at a later stage. (Food and Agricultural Organisation of the United Nations, 2010) Secondary Treatment The next stage, called the secondary treatment focuses on removing the remaining suspended and dissolved organic matter in the sewage. It is also known as the biological stage as the biodegradable organic contaminants that are dissolved would be broken down by microorganisms cultivated and added to the wastewater such as bacteria and protozoa. These microorganisms feed on the suspended and dissolved organic matter that remained from the primary clarifier. These bacteria can be categorised into aerobic or anaerobic bacteria, which is actually their need to oxygen. Generally, aerobes can degrade pollutants at a higher rate as opposed to anaerobes. (Waste Management, 2004) Numerically, the anaerobic treatment produces 0.1-0.2 kg biomass or sludge per kg BOD as opposed to the aerobic treatment which produces 0.5-1.5 kg biomass or sludge per kg BOD. (V. Jegatheesan, C. Visvanathan and R. Ben Aim, 2008) Also, some factors that increases their rate of degradation is the quantity of their food source and the temperature of the sewer. This secondary treatment can actually be carried out in numerous different methods. Anaerobic Treatment Anaerobic is defined as does not require oxygen. (MedicineNet.com) Firstly, the sewage is flown into anaerobic large tanks or ponds, therefore allowing anaerobic digestion to take place. Anaerobic digestion is when biodegradable material is broken down by the organisms without the presence of oxygen. The product of this digestion includes methane, carbon dioxide and sludge where to our advantage; methane can be used as an energy source categorising the anaerobic digestion as a renewable energy source. There is a membrane cover at the surface of the tanks/ponds which captures the methane and it is then used to generate electricity by combustion in a gas engine as well as reduce greenhouse gas emissions and odour. Besides that, mixing in the anaerobic process requires less energy compared to the aeration step carried out in the aerobic process. The emission of landfill gases into the atmosphere is also reduced with this anaerobic digestion. However, larger treatment plants are needed f or the anaerobic process as they have slower reaction rates. (Guerrero F. Omil, R. Mà ©ndez and J. M. Lema , 1998) The three main steps of this process are: 1. Hydrolysis and Acidogenesis C6H12O6 Æ’Â   2C2H5OH + 2CO2 (Organic compound) (Ethanol) (Carbon Dioxide) Hydrolysis is a process where the covalent bonds are broken with the use of water. Therefore the complex organic compounds are broken down into their constituent part by enzymes. Subsequently, acidogenesis is where acidogenic bacteria produces short-chain product by converting the hydrolysis products through fermentation and other metabolic processes. 2. Acetogenesis 2C2H5OH + CO2 Æ’Â   CH4 + 2CH3COOH (Ethanol) (Carbon Dioxide) (Methane) (Acetic Acid) 2CO2 + 4H2 Æ’Â   CH3COOH + 2H2O (Carbon Dioxide) (Hydrogen) (Acetic Acid) (Water) Acetogenesis is the process where acid and alcohol are converted into acetate, hydrogen and carbonic gas by acetogens categorised into homoacetogens, syntrophes and suphoreductors. The acetic acid production process may be carried out by Clostridium acetium, Actobacter woodii and Clostridium termoautotrophicum. The products of this process vary with the type of bacteria, temperature and pH levels. 3. Methanogenesis CO2 + 4H2 Æ’Â   CH4 + 2H2O (Carbon Dioxide) (Hydrogen) (Methane) (Water) CH3COOH Æ’Â   CH4 + CO2 (Acetic Acid) (Methane) (Carbon Dioxide) The third step of this process is methanogenesis, a form of anaerobic respiration in which methanogens (microbes) that exist in deep sediments convert soluble matter into methane. The majority of the methane production is from the conversion of acetic acid and the rest comes from the reduction of Carbon Dioxide by hydrogen. In addition to above, Sulphur, sulphite and nitrate under anaerobic conditions are reduced. To produce sulphides by sulphur reduction, Sulphur Reducing Bacteria (SRB) use sulphate or sulphite as electron acceptors and organic compounds such as acetate as electron donors. This is the main reason behind the rotten egg smell that exists from wastewater as they are kept for long periods of time under these anaerobic conditions. As for Denitrification however, nitrogen gas is produced by the reduction of nitrates using the organic compounds in the wastewater by denitrifying bacteria (DB). The bacteria generally require a carbon food source as energy for the conversion of nitrogen. 6NO3- + 5CH3OH Æ’Â   3N2 + 5CO2 + 7H20 + 6OH- (Nitrate) (Methanol) (Nitrogen Gas) (Carbon Dioxide) (Water) (Hydroxide) Aerobic Treatment The next step in this secondary treatment of wastewater is the activated sludge process where atmospheric air or pure oxygen is bubbled through the sewage, combined with microorganisms to create biological flocculants which reduces the organic content of the wastewater quite significantly. This occurs because of the bacteria and protozoa feed on the remaining organic materials in the wastewater. (Guerrero F. Omil, R. Mà ©ndez and J. M. Lema , 1998) Generally, the sewage is transferred into large ponds or tanks which are called surface-aerated basins that have floating surface aerators to promote the biological oxidation of wastewaters. These floating aerators create an oxygen rich aerobic environment in the sewage by removing most of the BOD therefore encouraging the growth of the aerobic microorganisms. Furthermore, the aerators provide mixing required for dispersing the air as well as contacting the reactants namely oxygen, microbes and wastewater. In the final clarifiers, the mixing process improves the settling of the biological solids. As the biological oxidation processes are highly dependent on the temperature changes, increasing the temperature to a certain threshold increases the rate of microbial decomposition. Surface aerated vessels mainly operate at temperatures ranging from 4  °C to 32  °C. (Beychok, M.R 1971) Nitrification is a process where the dissolved ammonia is removed by oxidizing it to nitrate which occurs during the activated sludge process. As a high concentration of ammonia is toxic to marine life, they have to be removed from the wastewater via the nitrification process. Nitrification can be divided into two steps, the oxidation of ammonia into nitrate by Nitrosomomonas and the oxidation of nitrite to nitrate by Nitrobacter. As the nitrifying organisms are chemoautotrophs, they use carbon dioxide as their source of growth and for cell maintenance. 2NH3 + 2CO2 + 3 O2 + Nitrosomonas → 2NO2- + 2H2O + 2H+ (ammonia) (nitrite ion) 2NO2- + 2CO2 + O2 + Nitrobacter → 2 NO3- (nitrite ion) (nitrate) The remaining solid particles flocculate to form larger and heavier particles that settle down more easily based on the biological reaction. Then, this mixture of wastewater and solid particles are pumped into a second clarifier or sedimentation tank where the solid particles are separated from the wastewater similar to the process in the primary sedimentation tank, where the resulting sludge is referred to as the activated sludge. Activated sludge is a biological material, brown in colour consisting of mainly saprotrophic bacteria that is produced by the activated sludge process which affects the purification process. In poorly managed activated sludge, a range of mucilaginous filamentous bacteria including Sphaetotilus natans can develop. These bacteria produce sludge that does not settle easily and therefore a possibility that a sludge blanket decanting over the weirs in the sedimentation tank that will severely contaminate the final effluent quality will form. A portion of the solid is recycled back into the surface aerated basins to be re-used in the nitrification process as the microorganisms in the sludge are still active. Excess sludge which eventually accumulates beyond what is recycled is called Waste Activated Sludge and then removed from the treatment process to maintain the ratio of the biomass to food supply in the balance (F/L balance). As a whole, the aerobic process is preferred as it is more stable, reliable and a clearer process understanding. Tertiary Treatment The final stage of the wastewater treatment is the tertiary treatment. This tertiary treatment is considered the advanced treatment stage of wastewater treatment. The purpose of this stage is to raise the quality of effluent before it is discharged into the receiving environment including the ocean, rivers or lakes. Various different methods can be used to undergo this tertiary treatment, however it is been found that the most cost-effective and environmental friendly method is lagooning followed by the Ultra-Violet disinfection. The wastewater may also be treated by chlorine but high chlorine content will harm the aquatic life that receives the water. A chlorine-neutralising chemical is often added before the stream is discharged in situations where required. However, if very high quality effluent is needed, an additional step, namely the polishing process that use sand or gravel filters and wetlands is carried out as the water from the treatment process are not safe enough to be co nsumed as there is still bacteria present. Below is a picture of a UV channel used in wastewater tertiary treatment. Source : City of Idaho, 2007 The sewage is then flowed into a series of large man made lagoons which are highly aerobic following the secondary treatment. Colonisation by algae and zooplankton is often encouraged due to their aerobic nature. The algae that grow in the lagoons captures trace amounts of organic nutrients and compounds in the wastewater which are then grazed by the zooplankton. The remaining algae and plankton settle to the bottom hence binding the nutrients in the sediment. Other microorganisms which are present in the sewage assist in reducing if not removing the harmful pathogens in water. Furthermore, the sewage left in these lagoons are exposed to the ultra violet radiation from the sun coupled with the grazing zooplankton, which creates a far from ideal environment for the bacteria which results in a great reduction their quantity. Where greater intensity of UV radiation or where there is insufficient, the sewage may be transferred into ponds that generate the UV radiation with ultra violet light bulbs for further disinfection. This disinfection eliminates pathogens and cist and is very use friendly as well as operates at a low cost. How it works is that the UV radiation actually damages the genetic structure of the bacteria, viruses and other pathogens hence inhibiting them to reproduce. A key advantage is that no chemicals are added to the sewage when the UV light method is used, hence no adverse effect on organisms that later consume the water. (http://wastewater-treatment.org) Generally lagoons need large spaces to operate however they do not need as much money and time as the traditional tertiary treatment wastewater procedures. The lagoons have also been found to be an important habitat for the birds. After the lagooning process, the treated effluent is ready to be released back into the environment and regarded as safe. Below are pictures of lagoons, the first one being an aerial view and the second one a close up. Source : City of Idaho, 2007 Source : City of Idaho, 2007 Disadvantages of the process First and foremost, to operate a wastewater treatment plant, a significantly large amount of energy is needed. In most communities, they are often regarded as the largest energy consumer. As previously mentioned, energy is generated by the biogas produced onsite, however in most situations, this only accounts for approximately half the plants energy requirements. This is due to the fact that the wastewater treatment plants are consistently operating to keep up with the ever increasing inflow of sewage. This consumption of external energy, other than the one being produced in the plant leads to high operational costs and also, more importantly affects the environment if the energy is sourced from fossil fuel. As the primary focus of the wastewater treatment is to remove contaminants from water, and eventually recycled into drinking water, recent studies show that the presence of certain contaminants including hormones and synthetic material can have an adverse impact even at minimal levels on the natural biota and for some cases, humans. For even processes that remove 99% of microorganisms, the final effluent declared as safe to drink may contain about 50 000 microorganisms. (Environmental Protection Agency United States, 2002) This is a threat when the receiving water is used for activities such as swimming or shellfish harvesting which need to be carried out in an environment with as little microorganisms as possible. BOD levels also affect the environment as although they are greatly reduced throughout the whole process the levels leaving the plant in most cases are high enough to damage the quality of the receiving environment. In the preliminary treatment, the main disadvantage highlighted is the high cost of the screening due to high labour and maintenance costs, as well as high maintenance cost of the machinery. In the primary treatment, the accumulation of sludge that is disposed off onto landfills that will eventually get full and hence taking up a larger area. In the secondary treatment however, there are quite a few limitations. Firstly, in the anaerobic digestion process, the bi-product requires substantial wet biomass handling and disposal. If this waste was to be disposed of in a landfill, often they would break down anaerobically, releasing methane into the atmosphere where methane is about twenty times more potent than carbon dioxide as a greenhouse gas, hence significant adverse effects on the environment. (ABC News, 2008) For the aerobic digestion however, the operating costs are marginally greater due to the additional costs needed to add oxygen. Skilled manpower is also needed for the operat ion and maintenance of this process. Finally, in the tertiary treatment, the major limitation is the lagooning process which depends highly on the climate condition that affects the toxicity of municipal wastewater and effects in the receiving environment which includes dissolved oxygen content in sewage, temperature of wastewater as well as efficiency of microbial processes. Hence, the effluent produced is of different qualities. For the UV disinfection, frequent maintenance and replacements incur additional costs. Besides that, not all organisms are actually affected by the UV radiation. (http://wastewater-treatment.org) The wastewater treatment process manages to remove almost all of the organic chemicals and metals present in the wastewater, however due to environmental degradation, the contaminants should not be discharged in large quantities as the contaminants may be toxic and stay in the environment for long durations. The contaminants will accumulate in the living tissue and be passed up along the food chain. Suggested Improvements to the Process General Improvements to the Process Overall Alternative sources of energy, especially renewable energy should be explored as wastewater treatment plants generally consume large amounts of energy. The generation of energy from the produced biogas during the process is insufficient to run the plant thought it helps reduce the environment consequences and overall operational costs. A named alternative to be considered is the use of hydroelectric power. The flow of water before the final effluent is released into the receiving environment could be used to generate electricity by the use of turbines. However, the capital and maintenance costs of the plant would increase. The volume of wastewater entering the treatment plant can be reduced by reducing the pipes diameter or by a inserting a valve is important as this smaller flow of influent leads to improved treatment, longer system life and a lower chance of overflowing. Overall, the quality of effluent will be increased with the reduction of influent flow as the waste will remain in the system longer; therefore more time is provided for settling, decomposition and aeration. Unfortunately, the volume of wastewater is largely dependent on the amount of water used in the community. Therefore campaigns and awareness should be carried out to help reduce the inflow of sewage by conserving the use of water. Odour Control By their nature, processes involved in the wastewater treatment, primarily from the anaerobic digestion process generate odour. Odour is actually one of the biggest concerns of the operators of the wastewater treatment as well as the general public. One way to overcome the release of odour into the surroundings is to capture the gas resulting from the anaerobic process and treat the trapped gasses. Examples of some treatment systems include activated charcoal bed systems, chemical scrubbers (often using hypochlorite solution), a compost pile type bio-filter and UV radiation treatment. The captured air may also be treated by pumping it through soil where the odorous compounds are absorbed into the soil particles and destroyed by naturally-occurring soil bacteria. (Wastewater treatment technologies) Other methods may include the addition of ferrous chloride to the wastewater collection system to reduce the release of hydrogen sulphide gas. Ion generators may also be installed onsite to help reduce the odours. Reaction Rates Anaerobic and specific aerobic microbial processes are temperature sensitive, and generally if the temperature is reduced the rate of reactions also decreases. Therefore, the climate conditions affect the quality of the final effluent through the lagooning process and open air ponds. As the biogas produced is used to generate power usually by combustion, the heat generated from this can be used to regulate the temperature in the lagoons. This is a cost-efficient way to curb climate conditions with minimal environment impacts. When the rate of the Nitrification process increases with the use of the ringlace fixed film system, the rate of reaction also increases. Ringlace is material developed in the 1980s by the Japanese and consists of a rope like material of high surface area and chemical composition conductive to bacterial attachment and growth. This system has been proven to increase the nitrification rates by 25% when the operation temperature is less than 1 °C. Apart from being cost effective due to its minimal installation and maintenance costs, the ringlace system also positively affects the BOD reduction and hinders algae growth. (Richard, M) Activated Sludge Process For the effective removal of organic matter, the activated sludge process requires sufficient oxygen supply and thorough mixing. The rate of which the microorganisms decompose can be increased tremendously if the aeration systems in the sludge tanks design be improvised as to provide a higher input of oxygen into the sewage. A key advantage to this design improvement would be the decreased amount of ammonia discharged into the environment as final effluent. Bio-solid Processing and Disposal The sludge that accumulates from the wastewater treatment processes has to be dealt with and can be done in a number of ways. As these bio-solids are highly toxic, they require intensive treatment before it is ready for disposal. For now, the conventional means of bio-solid treatment is sufficient as in to be disposed off in landfills. However, in time to come, the space requirements to accommodate these solids are not practical. Worthless sludge can be converted into marketable bio-solids through a process called Thermal Drying. The volume and mass of the solids are greatly reduced by evaporating the majority of their water content by the thermal dryers. To assist in forming larger aggregates of solids and releasing of water, chemical coagulants are usually used. Higher temperatures produce higher quality of bio-solids that can be sold as fertilizer. The product is easily handled, stored and transported. The main advantage of this process is that it can provide extra revenue to the plant. To the environment, it reduces odours resulting from the decomposition of the sludge. (Viessman, W Jr, 2010) A picture of the final product of the thermal drying is as below: (Source : Stibbe Management, 2006) On the other hand, thermal oxidation is an efficient process that converts bio-solids into an energy source, producing carbon dioxide, water and ash. The process occurs in a fluidized bed reactor that is highly energy efficient as it can be self-sustaining without auxiliary fuel when the combustion air is preheated to high temperatures. Heated air, gas, steam, water or oil which can be converted into electricity is recovered from these reactors. The advantages of this process include its low life-cycle cost, its ability to destroy all volatile solids and pathogens, minimising odour and offsets the energy consumption of the plant. Another approach involves treatment with lime (calcium oxide), which kills pathogens due to its high alkaline content. The heat generated from this reaction also helps in producing a drier final product. The waste sludge may also be treated by a means of anaerobic digestion which is similar to the anaerobic digestion which occurs in the water treatment process. In the anaerobic digestion of bio-solids, the waste activated sludge and primary sludge are mixed together without the presence of air. The digestion takes place in two steps and involves two distinct groups of bacteria. In the first step, acid-forming bacteria convert complex organic wastes (proteins, carbohydrates, lipids) into organic fatty acids. The second step is where bacteria convert these organic acids into methane, carbon dioxide and other trace gasses. As before, the methane produced may be used to generate energy by a means of combustion. This process stabilises a majority of the organic waste in the sludge thus allowing the bio-solids to be utilised as a soil conditioner. The stabilised bio-solids contain nitrogen, phosphorus and potassium which are beneficial to plant growth. Application of these bio-solids in ag riculture has lead to increased crop production. (Bio-energy from wastewater treatment) Conclusion The bioprocess involved in the steps of the wastewater treatment process namely the preliminary treatment which includes screening, grit removal the primary treatment which involves the primary sedimentation process, the secondary treatment which consists of the anaerobic and aerobic digestion and the secondary sedimentation and finally the tertiary treatment which is made up of the lagooning and the ultraviolet disinfection has been outlined in this report. The improvements as well as the key advantages were also discussed in the report. Improvements to the processes that would increase the quality of water discharged into the environment as well as the revenue of the wastewater company were focused on. Wastewater treatment is essential to ensure the preservation of our water and marine life and to the environment as a whole.

Sop Cassava Processing

|Document ID: |Standard Operating Procedures’ Title: |Print Date: | |ORIGIN-CA2 |CASSAVA PROCESSING |08/07/2012 | |Revision: |Written By: |Date Prepared: | |01 |Ayodele E. J.AJAYI, General Manager Operations |08/07/2012 | |Effective Date: |Reviewed By: |Date Reviewed: | |mm/dd/yyyy | |mm/dd/yyyy | | |Approved By: |Date Approved: | | | |mm/dd/yyyy | |Applicable Standard: None | |Company: ORIGIN Group of Companies Limited Vegefresh Foods Limited, Nigeria. | |In Africa, cassava is mostly used for human consumption in various forms ranging from boiling the fresh tuber to processing it into cassava flour. |[pic] Cassava starch in the making: freshly harvested roots roll | |along a conveyor belt at a processing plant in Brazil | | | |[pic] | | | | | | | | | |Cassava Starch. | | | | |Policy: It is a policy of this Company to provide Standard Operating Procedure documents that contain instructions on how to perform assigned tasks. Purpose: The purpose of this document is to ensure that routine tasks on the farm are performed safely, qualitatively and in compliance with applicable regulations. Below are some of the ways, this Standard Operating Procedure could have direct or indirect positive impact on ORIGIN Group’s Agric business performance: a) People need consistency to achieve top performance. This SOP will reduce system variation, which is the enemy of production efficiency and quality control. b) This SOP will facilitate training.Having complete step-by-step instructions helps trainers ensure that nothing is missed and provides a reference resource for trainees. c) This SOP can be an excellent reference document on how a task is done and what are the expectations from employees filling in on the jobs they do not perform on a regular basis. d) This SOP can help in conducting performance evaluations. They provide a common understanding for what needs to be done and shared expectations for how tasks are completed. e) Employees can coach and support each other if there is documentation available on exactly how various tasks must be done and everyone knows what their co-workers are supposed to be doing.This can also help generate a more cooperative team approach to getting all the daily tasks done correctly, everyday. f) This SOP encourages regular evaluation of work activity and continuous improvement in how things are done. Scope: This SOP is written for Production Managers, Lab Technician, Factory workers and Sales Distributors. The specific tasks within â€Å"Cassava Processing† are covered. This SOP does not cover the Cassava Production, Harvesting and Marketing. Responsibilities: The Production Managers, Lab Technician, Factory workers and Sales Distributors should be responsible for coordinating and implementing the Cassava Processing Factory and product sales tasks.The Production Manager is responsible for training and managing the Factory Workers, Supervisors, Lab Techs etc; Production Manager should supp ort the objectives policies of the Company and provide input to further development of SOPs. He/she would be responsible for planning, organizing, supervising and managing the activities of the entire factory and the routine maintenance of all factory equipment. Factory Workers are expected to discharge their duties efficiently and in compliance with the Standard Operating Procedures, work manual and equipment manual provided. The Standard Operating Procedures 1. 0 Cassava processing Cassava processing aims at increasing the quality and storability of cassava tubers.This enhances the ability of the farmers to develop additional products, such as baking products out of cassava flour. It further ensures reduction or total elimination of undesirable toxic constituents in cassava so that it is suitable for human consumption. A. Producing Cassava Flour and Chips: I. Using low-cyanide varieties – Freshly harvested cassava is peeled using a knife. The peeled cassava is then washed a nd sliced into smaller pieces (chips). These are then dried on a raised platform under direct sun for about 2 days or specially-made driers, until moisture content of about 8 to 10 % is reached. Properly dried chips become tough to break, but crumble into flour when hit with a hard item like a hammer.The drying process should be done continuously and the drying chips should not be exposed again to water to avoid molding. The chips may then be ground or milled into flour; dried chips store better than flour. II. Using high-cyanide varieties – Freshly uprooted cassava are peeled and sliced into smaller pieces (chips). The sliced chips are then dried in the sun for about 3 days to about 14 % moisture content. The chips are then soaked in water for 8 hours, and dried again to a moisture content of about 8 %. B. Producing Gari – Fermented cassava dough: Gari is a creamy-white or yellow dried cassava product, common in West Africa. It is prepared by peeling the outside of th e tuber skin and washed. The washed tubers are then grated using a grater.It is then packed in bags with holes to drain off the liquid and left to ferment for 1 to 5 days, depending on the preferred flavour. The fermented material is then pressed to let out the extra water leaving a cassava cake. The remaining cake is broken loose and spread on frying metal trays above a fire. The particles are fried until crisp and dry, about 10 % moisture content. The gari is then cooled, sieved and packed for sale or storage. C. Cassava Starch extraction After washing and peeling, roots are grated to release starch granules. The â€Å"starch milk† – water containing suspended granules then, separated from the pulp, after which the granules are separated from the water by sedimentation or in a centrifuge.At that point, the starch requires solar or artificial drying to remove moisture before being milled, sieved and packed. In artisanal production systems, daily starch output ranges f rom 50 to 60 kg of starch per worker, while semi-mechanized processing can yield up to 10 tonnes a day. In modern, fully mechanized starch extraction plants, daily output is as high as 150 tonnes. Cassava Processing Equipment I. Traditional cassava processing does not require sophisticated equipment. Processing cassava into gari requires equipment such as grater, presser and fryer. The traditional cassava grater is made of flattened kerosene tin or iron sheet perforated with nails and fastened onto a wooden board with handles.Grating is done by rubbing the peeled roots against the rough perforated surface of the iron sheet which tears off the peeled cassava root flesh into mash. In recent years, various attempts have been made to improve graters. Graters which are belt-driven from a static 5 HP Lister type engine have been developed and are being extensively used in Nigeria. Its capacity to grate cassava is about one ton of fresh peeled roots per hour. II. For draining excess liquid from the grated pulp the sacks containing the grated pulpy mass are slowly pressed down using a 30-ton hydraulic jack press with wooden platforms, before sieving and roasting into gari. Stones are used in traditional processing to press out the excess moisture from the grated pulp.Tied wooden frames are used for this purpose in places where stones are not available. Pans made from iron or earthen pots are used for roasting the fermented pulp. Fuel wood is the mad or source of energy for boiling, roasting, steaming and frying. Fuel wood may not be easily and cheaply obtained in the future because of rapid deforestation. III. Slight changes in the equipment used in processing can help to save fuel and lessen the discomfort, health hazard, and drudgery for the operating women. The economic success of any future commercial development of cassava processing would depend upon the adaptability of each processing stage to mechanization.However, the first step to take for improvement of cas sava technologies should be to improve or modify the simple processing equipment or systems presently used, rather than to change entirely to new, sophisticated, and expensive equipment. Storage of cassava processed products Processing, particularly drying and roasting, increases shelf life of cassava products. Good storage depends on the moisture content of the products and temperature and relative humidity of the storage environment. The moisture content of gari for safe storage is belong 12. 7%. When temperature and relative humidity are above 27 °C and 70% respectively, gari goes bad (Igbeka 1987). The type of bag used for packing also affects shelf life depending on the ability of the material to maintain safe product moisture levels.Jute and hessian bags are recommended in dry cool environments because they allow good ventilation (Igbeka 1987). When gari, dried pulp and flour are well dried and properly packed, they can be stored without loss of quality for over one year. Dr ied cassava balls (â€Å"kumkum†) can be stored for up to 2 years (Numfor end Ay 1987). â€Å"Chickwangue†, â€Å"Myondo† and â€Å"Bobolo† can be preserved for up to 1 week but they can be kept for several more days when recooked. Cassava leaves as vegetable I. Cassava shoots of 30 cm length (measured from the apex) are harvested from the plants. The hard petioles are removed and the blades and young petioles are pounded with a pestle in a mortar.A variation of this process involves blanching the leaves before pounding. The resulting pulp is then boded for about 30-60 minutes. In some countries, the first boiled water is decanted and replaced. Pepper, palm-oil and other aromatic ingredients are added. The mixture is then boiled for 30 minutes (Numfor and Ay 1987). Unlike the roots that are essentially carbohydrate, cassava leaves are a good source of protein and vitamins which can provide a valuable supplement to predominantly starchy diets. Cassava leav es are rich in protein, calcium, iron and vitamins, comparing favorably with other green vegetables generally regarded as good protein sources.The amino acid composition of cassava leaves shows that, except for methionine, the essential amino acid values in cassava exceed those of the FAO reference protein (Lancaster and Brooks 1983). II. The total essential amino acid content for cassava leaf protein is similar to that found in hen's egg and is greater than that in oat and rice grain, soybean seed, and spinach leaf (Yeoh and Chew 1976). While the vitamin content of the leaves is high, the processing techniques for preparing the leaves for consumption can lead to huge losses. For example, the prolonged boiling involved in making African soups or stews, results in considerable loss of vitamin C. III. Cassava leaves form a significant part of the diets in many countries in Africa.They are used as one of the preferred vegetables in most cassava growing countries, particularly in Zaire, Congo, Gabon, Central African Republic, Angola, Sierra Leone, and Liberia. The cassava leaves prepared as vegetable are called â€Å"sakasaka† or â€Å"pondu† in Zaire, Congo, Central African Republic and Sudan, â€Å"Kizaka† in Angola, â€Å"Mathapa† in Mozambique, â€Å"Chigwada† in Malawi, â€Å"Chombo† or â€Å"Ngwada† in Zambia, â€Å"Gweri† in Cameroon, â€Å"Kisanby† in Tanzania, â€Å"Cassada leaves† in Sierra Leone, â€Å"Banankou boulou nan† in Mali, â€Å"Mafe haako bantare† in Guinea, and â€Å"Isombe† in Rwanda. They are mostly served as a sauce which is eaten with chickwangue, fufu, and boiled cassava. Revision History: Revision |Date |Description of changes |Requested By | |01 |08/07/2012 |Initial Release | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | References: http://www. fao. org/index_en. htm http://www. fao. org/ag/agp/agpc/gcds/ [pic]The Global Cas sava Partnership, a consortium formed – under the auspices of the FAO-facilitated Global Cassava Development Strategy – by international organizations, including FAO, CIAT, IFAD and IITA, national research institutions, NGOs and private partners. International Institute of Tropical Agriculture (IITA). Starting a Cassava Farm – IPM Field Guide for Extensions Agents. 2008; International Institute of Tropical Agriculture (IITA). Disease Control in Cassava Farms. IPM Field Guide for Extension Agents; International Institute of Tropical Agriculture (IITA). Weed Control in Cassava Farms. 2000. IPM Field Guide for Extension Agents; In-Service Training Trust (ISTT). Cassava Production Field Guide. 2008. NRDC Campus, Lusaka, Zambia. ———————– ORIGIN Group’s SOP: Confidential and Proprietary Page 6

Legalizing weed

THESIS STATEMENT: Legalizing marijuana proves to have more beneficial effects or consequences on our society as a whole than banning it, as could be proved by other countries wherein purchase of marijuana is legalized.Legalizing marijuana had been one of the most controversial issues on many societies. Marijuana could be obtained from a plant named â€Å"cannabis sativa†. Marijuana’s most dynamic element is delta tetrahyddrocannibino or simply THC. THC is the one responsible for the way people gets high once they used marijuana. Marijuana is called in a number of ways such as grass, mary jane, smoke, pot, weed, etc.   Most people have certain connotation that marijuana is something which is bad and harmful. Most think of marijuana as nothing but illegal drugs. However, marijuana also has its medical uses which would be discussed later on this paper. There is also wide range belief that marijuana could either make or break a person. If marijuana is used on medicinal pu rposes only then the results are considered helpful but when used for other reasons then the result would be harmful. These claims would all be tested on this paper. The main question would be whether legalizing marijuana would cause more positive or negative effects on the individuals using it as well as on the society as a whole.ARGUMENT ON LIBERTYMany people condemn the use of marijuana because of its harmful effects on the society as well as on the individuals living in that particular society. It is basically because of the people’s fear of the harmful consequences of marijuana on which they argue that cannabis sativa be banned. The prohibition of using marijuana is often supported with claims like legalizing it would cause serious harm on our society especially on young adults. There are claims that most people under the age of 18 may have open access on marijuana. Another factor is some people beliefs that even people whose 18 years of age and above often do not know t he consequences of their actions and thus they could not decide for their own selves. There are claims that continuous use of marijuana would result to violence and in this regard marijuana really ought to be banned.First and foremost, an argument using John Stuart Mill as well as the liberals’ point of view regarding freedom is due on this paper. Mill strongly believes that the state as well as the other people does not have any right whatsoever to interfere with other people’s businesses unless the said people’s activities prove to be harmful on the society or on other individual. Not simply because other people find’s one action to be offensive or not to that person’s liking it already follow that that person has a right to limit or to prohibit other people from doing exactly what they please. For one, Person A may not find marijuana to his liking and thus vow to never use it, however, not simply because Person A does not like marijuana it alrea dy follows that he could prohibit Person B from using marijuana.The state could also not intrude on Person’s B’s freedom to smoke marijuana provided that Person B does not cause the state or the state’s individual any harm. There are arguments which state that most people who use marijuana gets violent and thus marijuana should be prohibited. In a way marijuana could be likened to alcoholic beverages. There are people who tend to get violent once they get drunk but most people often just go home after drinking and then they go to sleep. Thus, if alcohol could be legalized then why is it that marijuana ought to be banned? Violent person tends to get more violent once they get drunk, and such is also the case with marijuana. Marijuana makes a person feels high but it does not make a person violent as long as you are not inherently a violent person.ARGUMENT ON COST AND FAILUREOn terms of cost to the government there are people who believe that once marijuana is leg alized a lot of people would have open access to the drug thus heightening the likelihood that more people would have to go to rehabilitation centers in order to cure them of their addiction. These people argue that expenses used on rehabilitation centers are supported by people’s taxes thus legalizing marijuana would be an additional burden for the rest of the society. However, these arguments do not really prove to be valid, and often they are found to be unsupported or based on very shaky grounds of argumentation added to the fact that prohibition of the use of marijuana is not really effective.Most countries and individuals do not really support the legalization of marijuana especially since they consider marijuana as harmful. Marijuana may be harmful but so is cigarette and alcohol and yet cigarettes and alcoholic beverages are legal for use. With the endless efforts of the government to hunt or to track down people who uses and who traffic marijuana on the country peopl es taxes just go to waste. In contrast to the arguments of those who are not in favor of legalizing marijuana on the basis that rehabilitation centers costs a lot and is a burden to the society as a whole, pro legalization of marijuana would argue that the endless efforts of the government and of other individuals to prohibit the use of marijuana is what really costs a lot of money.The endless campaign against drugs, the imprisoning of good people who just happened to like using marijuana in spite of their being peaceful, these are all a waste of time and money. Compared to other drugs marijuana is not that harmful and marijuana is just as addicting as cigarettes and alcohol yet these two are not prohibited by the government (Weinstein, 1999). Besides, if we would look at it in a certain way we would see that everything around us is indeed harmful once taken in excess. For one, high caloric foods got harmful effects on our body yet they are not banned. In a way marijuana is just lik e those foods with high calorie, and excess use of it could have harmful effects on one’s body yet when it comes to eating the government does not really imprison people who eat in excess.Aside from that instead of wasting the government’s resources as well as the people’s taxes on chasing marijuana sellers and users, the government should instead legalize the use of marijuana and earn profit from it by putting taxes on the sells of it. Should truth be told the government is just making marijuana traffickers richer by illegalizing it in spite of the fact that they could not really stop the use of marijuana no matter what they do. People still use marijuana in spite of it being illegal and the government is spending money on the prohibition of it without earning anything in return, thus, they must reverse their strategy and earn profits from marijuana and spend most of their time and resources on chasing the real harmful criminals such as killers, robbers, etc.AR GUMENT ON ADDICTION AND IGNORANCEThere are people who fight the legalization of marijuana to the extent. In spite of the medicinal uses of marijuana these people still do not wish to legalize it due to certain arguments like patients would rely more on marijuana to alleviate their pain instead of on normal medical procedures. This particular belief was mostly caused by their belief that marijuana is addicting. Just like all drugs they believe that marijuana is addicting and thus it would be hard to quit once you started using it especially since it causes withdrawal syndromes. Additional factor is their belief that legalizing marijuana would heighten the numbers of people using it.The reason why many people turn against marijuana and why they dislike it so much is mainly due to their ignorance. Many people views marijuana as addictive and they believe that it causes harmful effects on individuals. During the late 1930s marijuana was assumed to be some kind of a narcotic mainly becau se they were mostly used by people who use narcotics such as opium and the like without making any effort at all to conduct a research on the real effects of marijuana. The government tried to fight marijuana by being silent and giving harsh penalties believing that by doing so they could protect their youths from being corrupted by marijuana. However, silence resulted to ignorance resulting people to believe the worse on marijuana.As mentioned earlier people believed that marijuana is addictive. Yet a research conducted by Dr. Jack Henningfield and Dr. Neal Benowits proved that marijuana is not really addictive. They proved that cigarettes and alcohols are in fact more addicting than marijuana. It was also proven that marijuana does not cause any withdrawal syndromes on those people who wish to quit from using it (Wikman, 2000). Also in regards to others belief that legalizing marijuana would increase the people using it, Holland would be the finest example to rebut that claim. Mar ijuana was already legalized in Holland since 1976 and since that time the number of people using marijuana decreased by 40%. Other states in America which also legalized the use of marijuana did not show any proof that legalizing marijuana would increase the number of people using it (Meiners, 2000).CONCLUSIONOverall this paper gave sufficient evidences that the legalization of marijuana would more likely cause positive effects on the society than negative ones. Study showed that marijuana is not really effective and that alcohol and nicotine is in fact more addictive and more harmful than marijuana. Also, anything in excess is bad and thus marijuana should be blamed for people’s misbehavior because even when someone does not smoke marijuana yet he drinks a lot then it would also surely cause harmful effects on that person’s body. Another point is that not since you views something as distasteful it would also necessitate that that person would abide by your rules and would quit doing what he wants to do especially if it does not cause any harm on the society and on the individual living on it. The government should also focus their attentions more on more serious crimes than the usage of marijuana. The government should also try to earn profit from the sells of marijuana to better help the nation. Marijuana is nothing really serious especially if not taken in excess thus, marijuana ought to be legalized.References:Wikman, Eric. â€Å"Legalization of Marijuana.† 2000.Meiners, Roger E. The Legal Environment of Business Cincinnati: Ohio South Western CollegePublishing, 2000.Weinstein, Sanford. The Educator’s Guide to Substance Abuse Prevention Mahwah, N.J.Lawrence Erlbaum Associates, Incorporated, 1999.

The Truman Show - Religion - 1925 Words

The movie, The Truman Show, can be related to religion in many ways. Jim Carrey stars as Truman Burbank, a 30-year-old man, whose whole life has been the plot of an acclaimed TV show. The movie shows how reality can be altered and created when confined into a small space. The movie is set in the town of Sea Haven, which is built inside a studio in Hollywood, California. Truman was born and adopted by a corporation, and thats when the show started. Throughout the movie, there are three religious points brought up, the issue of free will, God as all knowing, and the ideas of Calvin. The director has made it clear that religion plays an important role in everybodys life, and it is hard to escape from God. Truman Burbank was born and raised†¦show more content†¦Truman gets off his boat and walks up the stairs toward a door to the real world. He speaks to Christof for the first time, and he is given the choice to stay in his protected world or to go out into the unknown. Truman chooses to leave. John Calvin, writer of Institutes of the Christian Religion, believes that knowing and understanding God and ones self are interrelated. Calvin claims that one can not fully understand God unless they truly know and understand themselves, and vice versa. Truman did not know himself as much as he believed he did. He was controlled by a TV show and did not even know it. Things occurred in Trumans life for entertainment purposes only, not because of natural occurrence. Truman believed that he lived a life that was truly his own, only to find out later on that it was the life that his creator wanted it to be. When Truman finally realized the life he was living was not his, he chose to try to escape from it. At this point he began to understand himself and what he truly stood for, his freedom. When he was about to leave Seahaven, he spoke with Christof or you could say he found his creator. When Christof first gets to talk to Truman, when he is at the exit of the studio, he says I am the creator...of a television show that gives hope and joy and inspiration to everybody. The pause after I am the creator gives this conversation the feeling of Truman talking to God, likeShow MoreRelatedBrave New World by Aldous Huxley1093 Words   |  4 Pagesproduction The Truman Show by Peter Weir and Aldous Huxley’s novel Brave New World. In each media, the society depicted seemed outwardly perfect, and the citizens were content. The individuals remained content through complete government control. With every society’s strength is a weakness, interestingly enough, the Achilles’ heel of both perfect societies is totalitarianism and social conditioning. The fact of the matter is that not everyone will be the standard. The Truman Show is a 24/7 recordingRead MoreThe Allegory Of The Cave, By M. 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