Evaluation of phosphorous and nitrogen removal in alligator and dairy wastewater via lime and bentonite precipitation
Master of Science in Biological and Agricultural Engineering (MSBAE)
Biological and Agricultural Engineering
In many situations, the manure produced by confined animal feeding operations (CAFO) needs to be treated before being land applied in order to prevent negative impacts on the environment. Treatment methods are focused on reducing organics, recovering nitrogen and phosphorous. The purpose of this study is to evaluate the efficacy of burnt-lime (Ca(OH)2) and bentonite clay precipitation system of recovering phosphorous from dairy wastewater and alligator wastewater and trapping any possible emissions of ammonia (NH3). Wastewater samples of flush dairy manure from a collection pit, dairy wastewater from an anaerobic lagoon and alligator wastewater from an anaerobic lagoon were investigated in this study. The addition of burnt lime and bentonite clay solutions were found to be effective in removing 88.18% of total phosphorous (TP) and 100% of dissolved phosphorous (PO4-) from the flush dairy manure by the addition of 9% by volume of 10% lime solution (1:9 Ca(OH)2 to water) along with 0.9% by volume of 5% bentonite clay solution (24.25g in 485 mL water). The same concentrations of lime and clay solutions added in the same proportions to dairy lagoon wastewater resulted in a 99.86% reduction of TP and a 98.58% reduction of PO4-. The addition of 9.009% by volume of lime and 0.9% by volume of clay solutions to the alligator wastewater resulted in 99.95% and 95.76% removal of TP and PO4- respectively. The addition of lime and clay solutions resulted in raised pH of the wastewater. This led to a hypothesis of ammonium (NH4+) being converted to ammonia (NH3) and volatilized into the atmosphere. Acid traps were used in this study to evaluate the NH3 concentrations of wastewater, were found not to contain any detectable concentrations of ammonia indicating that there was minimal volatilization of NH3. The higher alkalinity values observed in all the wastewater samples indicated the presence of ammonium (NH4+) complexes in wastewater as ammonium hydroxide (NH4OH). Therefore, the addition of lime and clay solutions effectively removed most of the P present in the wastewater samples and there were no ammonia emissions detected.
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Bukkapatnam Tirumala, Srikanth, "Evaluation of phosphorous and nitrogen removal in alligator and dairy wastewater via lime and bentonite precipitation" (2012). LSU Master's Theses. 1543.
Sheffield, Ronald E