Analysis of Total Suspended Solids and Dissolved Oxygen Concentrations of the AlgalBacterial Selenium Removal ABSR system Veasna Hang Abstract The Algal Bacterial Selenium Removal ABSR system has been very effective at removing Selenium from agricultural drainage water that enters the water systems of the San Joaquin Valley CA Although selenium levels are significantly lower in the effluent of the ABSR system Dissolved Oxygen DO levels in effluent water have been found to be significantly lower than normal If DO levels dip under 5mg L saturation aquatic life is put under stress At levels 1 2mg L saturation fish would likely start to die off The purpose of this study was to examine the affect the ABSR system has on the DO levels in its effluent Water samples were collected from two ABSR pond systems in Panoche CA where there are two systems with different pathways The Low cost system has influent going into a high rate pond HS and then goes into a reduction pond RS so anoxic bacteria uptake the selenium The High efficiency system has influent water going into a reduction pond RN and then put through as sand filter NSSF The effluent of both systems were tested for Biochemical Oxygen Demand BOD and Total Suspended Solids TSS levels which are related to DO saturation levels in water In the Low cost system levels from the effluent showed increases in both BOD and TSS levels In the High efficiency system there are increases in BOD and TSS levels as well Although increases in both BOD and TSS levels were found the High efficiency system was able to stay within EPA limits The Low cost system failed to meet EPA standards for TSS levels In conclusion the effluent coming out of the High efficiency systems will not substantially lower DO saturation levels to dangerous limits Introduction Much of the drainage water in the San Joaquin Valley is contaminated by runoff from land that is used for agricultural purposes Green 2001 Agricultural waste and chemicals are often found in high concentrations in the discharge from agricultural drainage systems Oswald 1988 The discharge enters the San Joaquin River by way of sloughs that lead directly to the river Green 2001 The runoff from the agricultural land negatively affects the water quality of the river which then affects the wildlife surrounding the river Green 2001 and Zarate 1999 Dissolved oxygen DO plays a vital role in determining water quality Like organisms on land fish and other aquatic organisms require oxygen in order to survive Oxygen enters the aquatic system through several pathways One way is from the photosynthesis process of aquatic plants Water Shedds Dissolved Oxygen elect Comm 2002 During photosynthesis plants release oxygen aquatic plants release this oxygen into the water Another way for oxygen to enter is through the water air interface where oxygen from the atmosphere is dissolved into the water Gas solubility increases as water temperature and salinity decrease Water Shedds Dissolved Oxygen elect Comm 2002 There are also processes that will use up the dissolved oxygen in the water These include the respiration of organisms and the decomposition of organic material by bacteria If DO levels drop under 5mg L saturation aquatic life is put under stress At levels or 1 2mg L fish would likely suffocate to death Water Shedds Dissolved Oxygen elect Comm 2002 The site in the Panoche Drainage District in the San Joaquin Valley uses the ABSR system The purpose of the ABSR is to remove Selenium Se on top of Nitrate It consists of three ponds The first is a reduction pond RP where Anoxic Bacteria are used to uptake the selenium which is often in the form of selenate SeO62 Quinn In the RP organic carbon in the form of Molasses is added to promote bacteria activity The second pond is an HRP similar to the one in the AIWPS Here Algae grows and assimilating carbon dioxide ammonium and phosphates There are two different pond systems within the Panochec system One is the Highefficiency system and the other is Low cost system The differences between the two include a different arrangement of the different ponds and molasses is added to the High efficiency pond as a nutrient for bacteria Influent Agricultural Waste Water Reduction Pond High Rate Pond Molasses Added Selenate and Nitrate Reduced CO2 and Nutrients Added Nitrate Assimilated by Growing Algae High Rate Pond Reduction Pond Molasses Removed Algae Grows CO2 Consumed Algae Settles Selenate and Nitrate Reduced Sand Filter Effluent Algae Removed Effluent High Efficiency System Low Cost System Table 1 The Panoche ABSR systems There have been prior research projects that have looked at the affects and usefulness of these systems In 2001 Diana Stuart researched the ABSR system in Panoche for its effectiveness in removing Selenium Stuart D 2001 Stuart sought to show whether or not the ABSR system would effectively remove the bioavailability of Selenium in the effluent water Stuart concluded that although the system was effective in removing selenate it did not remove Organic Selenium effecitively Stuart 2001 Another project by Atsushi Hatano in 2001 focused on Nitrogen removal in the AIWPS in Delhi and Panoche Hatano s goal was to find out transformation pathways and the removal rates of nitrate nitrite and ammonium nitrogen in the AIWPS Hatano 2001 Hatano also wanted to determine if pH DO and temperature had on affect on the transformation pathways and the removal rates Hatano concluded that the AIWPS in Delhi was more effective at removing Nitrogen than a similar system in Panoche Hatano 2001 Also it was found that only temperature had a substantial affect on the transformation pathways and removal rates Previous research was also done on the cost effectiveness and efficiency of the AIWPS technology In a study by Zarate and his group the application of the AIWPS technology to chemically contaminated agricultural drainage water was studied using a demonstration plant The study concluded that the technology was efficient removing enough selenium and nitrates to meet monthly and annual load targets for the San Joaquin River Zarate 1999 Also it proved to have low capital costs and low operational costs with robust performance and a user friendly operational system Zarate 1999 This project will differ from previous projects because it will focus on the rate of removal of Biochemical Oxygen Demand BOD and Suspended Solids SS in the ABSR system in Panoche BOD and SS are important to look at because
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