Water Treatment System for a Small Winery - Term Paper Example

WATER TREATMENT SYSTEM FOR A SMALL WINERY Name Course Professor (Tutor) Institution Date Table of Contents Sedimentation Tank 3 Anaerobic Tank 4 Aerobic Tank 5 Settling Pond 6 Storage Dam 6 Biological Oxygen Demand (BOD) 7 Chemical Oxygen Demand (COD) 8 Alteration of PH Levels 8 Removal of Grease from Waste Water 9 References 11 Sedimentation Tank This will be the primary (first stage) in the treatment of waste water. An approximated 30% of the heavy particles as well as floating materials will be removed at this stage (Wangatia, 2012). Depending on the nature of sludge, the waste water will be conditioned prior to this phase using chemical means in which case mineral salts or organic compounds will be added. Alternatively, depending on the economics to be involved and the quality of water, thermal conditioning will be done where the sludge will be constantly subjected to high temperatures (150-200) degree Celsius for a duration of about 45 minutes. Besides, It is possible to thicken sludge at this stage depending on its nature – floatation will be preferred for biological and chemical sludge where as centrifugation comes will come in handy when handling sludge at the primary level. The main reason for dewatering or thickening of sludge is to reduce sludge volume by getting rid of excess water that is characteristic of raw sludge. However, the sedimentation process at this stage is majorly affected by the density and volume of the suspended solids within the influent (Nilsson & Dahlstrom, 2005). It is for this reason that the inlet to the sedimentation tank will be designed with a series of screens that will help to eliminate large solids – usually in the range of (10-25) square millimeters. Scraper arms will also be incorporated to allow for the skimming of the floating matter. As Mishra and Mahanty (2012) observe, the sedimentation tank may be designed in two main ways: as an elongated rectangular pond where water velocity is limited to 0.3m/s or the circular type. In our case we’ll adopt the circular system that is known to facilitate efficient and quick settling of solids. Figure 1: Design of a Sedimentation Tank. Anaerobic Tank In this tank, the anaerobic bacteria will be allowed time to act on the organic matter under de-oxygenated conditions The active micro-organisms in this zone include sludge worms that work in conjunction with a certain type of protozoa that thrive in absence of oxygen (Wangatia, 2012). The depth of this tank will range between (2-5) m and will receive waste water directly, from the sedimentation tank. As Nilsson & Dahlstrom (2005) argue, the anaerobic tanks will not only serve to reduce the volume of waste water but will also allow sludge enough time to stabilize (settle). This will see to it that by the time the effluent leaves, sludge has already been reduced by about 35%. Through the decomposition process in this stage, the sludge will undergo a number of phases; proteins, fats and carbohydrates are slowly but steadily broken down into carbon dioxide and methane gases – a product called biogas that may serve as a cheap source of electricity or fuel. Overall, the anaerobic bacteria will be allowed 20 days to work at optimal temperatures of about 35 degree Celsius; this will enhance hygienisation and stabilization of the sludge. Depending on the retention time and temperature, pathogens will be significantly reduced at this stage (Mishra & Mahanty, 2012). Moreover, a provision will also be made at this stage to allow for the entrance of screened sludge through the pond bottom from where it will be subsequently drawn at different positions and conveyed to drying beds. Additionally, a scraper arm will also be included to skim any floating debris. Aerobic Tank Here, the organic matter will be acted upon by aerobic bacteria in presence of oxygen. The design of the tank will be shallow enough to allow sufficient aeration through natural means. For shallow ponds, natural aeration is good enough as satisfactory oxygen is supplied by photosynthetic algae or even through surface aeration. The aerobic ponds will allow for a retention time of (4-6) days and will be designed with a large surface area at a depth of about one meter to permit for sunlight penetration and consequently support photosynthetic processes (Mishra & Mahanty, 2012). The lion’s share of the harmful micro-organisms will also be killed from here – the chamber has temperature ranges of about (65-70) degree Celsius. The algae-bacteria relationship here will be purely symbiotic in that as the algae supplies oxygen to aerobic bacteria through photosynthesis, the bacteria will in turn produce carbon dioxide during the breakdown of organic matter. It, therefore, follows that the performance of the waste water stabilization pond at this phase will be highly dependent on the relationship between these two organisms. Further, the quality and quantity of effluent from this circular tank will be good as such lagoons allow for high waste loads. This is unlike the deep ponds where mechanical stirs are required leading to high energy requirements. Figure 2: Illustration the natural aeration process. Settling Pond This is where the biologically treated effluent from the aerobic tank will be received and allowed enough time to undergo further sedimentation (Nilsson and Dahlstrom, 2005). Its design will incorporate a soil foundation so as to allow in the soil microbes to catalyze the absorption of the remnant organic matter. The size of this tank will be designed three times smaller when compared to the storage dam for ease of managing the effluent quality. It is also at this phase that the chemical nutrients will be closely monitored and manipulated as need may be to optimize the characteristics of the resultant discharge. Moreover, as Wangatia (2012) observes, the settling pond will provide for the balancing of waste water in cases of overflow though, it will call for periodic cleaning to maintain the quality of water coming from here. Besides, cases of short-circuiting will be avoided at all costs, through proper spacing, to avert cases of poor quality discharge. Storage Dam This pond will be designed to specifically receive the effluent from the settling tank for the purposes of storage (Wangatia, 2012). The resultant water at this phase will be assumed to be of high quality hence minimal sludge will be obtained from here. In addition, the quality of water in the storage dam may further be improved through oxidation of ammonia to nitrates or by way of lowering the Biological Oxygen Demand (BOD). Further, the concentration of soluble nutrients like phosphorus will also minimized further from here. As need may arise, additional but elevated tanks will be incorporated into the system especially if the treated water is required for irrigation purposes. Biological Oxygen Demand (BOD) The Biological Oxygen Demand (BOD) is a parameter that is used to determine the amount of oxygen that waste water is likely to consume. Nilsson and Dahlstrom (2005) define BOD as the amount of oxygen required by aerobic bacteria so as to effectively stabilize all the decomposable organic matter. This parameter will be determined from the different tanks over a period of five days at a temperature of 20 degree Celsius and the results analyzed in the laboratory (Grady, 2010). A higher BOD serves as a clear pointer to high levels of organic carbon and this translates to high polluting capability for the given waste. However, it is important to note that the highest consumer of oxygen in waste water is the organic load as such, this will form the key focus during the design of our waste water stabilization plant. A number of measures will be integrated in the treatment process to guarantee a reduction on BOD levels: the mechanical reduction of suspended solids and subsequent secondary treatment (through aerobic processes) will go a long way in reducing the BOD in waste water by about 80%. High BOD has been known to easily lead into oxygen depletion in the receiving waters; this has very adverse effects on the aquatic life and the ecosystem at large. The analysis and monitoring of both influent and effluent quality will be a daily activity to guarantee the performance of the proposed system. Chemical Oxygen Demand (COD) The Chemical Oxygen Demand is also another parameter used to define the polluting power of wastewater; it will have to be kept at a bare minimum if water quality is to be enhanced. The commonest to be employed in reducing COD will involve the inclusion of activated sludge – bacterial propagation in the aerated chamber- within the treatment plant. Since our system is meant for an industrial application, it will also be possible to realize COD reduction through chemical means (Tucker & D’Abramo, 2008). More specifically, we’ll apply hydrogen peroxide in the settling tank – the compound is known to attack organic matter in waste water through hastened degradation process thereby bringing down the measured level of COD. Ammonium Phosphate will also be applied in the aerobic tank at the rate of 1000g for every 100,000L in the quest to lower COD at the initial stages. It is, however, important to note that the efficiency in COD removal rate is based on the size of the organic molecules; biological treatment processes are the best when handling smaller the particles. To effectively deal with the issue of COD, enough oxygen will be required but long retention periods will also be necessary for the micro-organisms to have ample time in breaking down the complex organic matter present. Alteration of PH Levels PH is basically an approximation of concentration of hydrogen ions in a given solution (Tucker & D’Abramo, 2008). The PH value, in our case, will be an important component of waste water treatment process because it has a direct bearing on the accompanying biological processes. Grady (2010) explains that basic or acidic conditions do alter the enzymatic structure and by extension enzymatic growth in a treatment plant. The author further opines that during the night, PH levels will be found to fall considerably with reduction in photosynthetic activities but the same rises during the day as photosynthetic activities surpass respiration leading to a reduction of carbon dioxide in any given water mass. The optimum PH range for most of the micro-organisms is (6.5-8.5) and this is the value we shall seek to sustain. Permanent as well as temporary measures will be incorporated here. Temporary measures will include the addition of bases or acids depending on the PH value. Long-term measures and the most sustainable will be to include mechanical agitators especially where sludge is heavy. Figure 3: Depiction of PH cycling for a 3-day period in two ponds (Adapted from Tucker & D’Abramo, 2008) Removal of Grease from Waste Water Grady (2010) advises that the removal of any hydrocarbon from waste water is dependent on the status of the contaminant – the physical form (emulsified or free) as well as the degree of concentration. Free grease comprises of large oily droplets (usually less than 20 micron) where as emulsified grease is made up of small droplets that are less than 20 microns (Tucker & D’Abramo, 2008). The authors further explain that free grease can be seen with naked eyes floating on the water where as the emulsified form will be seen as ‘sheen’ in the water. The issue of concentration will be examined from the comfort of our laboratories. The free grease – concentration exceeding 70mg/l - will be removed with the aid of grease skimmers or better the grease water separator where as the emulsified form will first be broken down and the resultant free oil skimmed. Since our system is designed for industrial purposes, a clay filter will be incorporated in the long run – removes about 90% of the grease especially when used in conjunction with an activated carbon filter (Grandy, 2010). References Grady, P. (2010). Biological Wastewater Treatment. Marcel Decker, Inc., N.Y Tucker, C. & D’Abramo, L. (2008). Managing High pH in Water Pond. Southern Regional Aquaculture Cente, U.S. Nilsson, C, and Dahlstrom, H. (2005). Treatment and Disposal Methods for Wastewater Sludge in the Area of Beijing, China. Department of Water and Environmental Engineering; Lund Institute of Technology, Lund University Wangatia, M. j(2012). Socioeconomic Implications of Solid Waste Management Practices. Community Disaster Interventions (CDI), Nairobi, Kenya Read More