Study On Nitrogen And Phosphorus Removal In A~2/O Process Using Brewage Wastewater As External Carbon Source

According to "cities and towns sewage treatment information system data" which is promulgated by the Department of Housing and Urban, the low ratio value of carbon to nitrogen (C/N) was the prevalence of China’s urban sewage treatment plant, the C/N value of majority urban sewage was only3to4, which makes electronic donor shortage when biological denitrification, can not meet the metabolism of the microorganisms in the system, thereby affecting the efficiency of biological nitrogen and phosphorus removal. Many domestic sewage treatment plants were using low molecular weight substances, sugar and other traditional external carbon source, in order to improve the removal efficiency of nitrogen and phosphorus. However, the costs of these external carbon sources were relatively high, and there were some shortcomings which can not be ignored. In order to reduce the cost of sewage treatment, some new external carbon source had become a research focus. This paper focuses on the feasibility of brewery wastewater as external carbon source, different concentrations of brewery wastewater impact on the system, and the removal rate of nitrogen and phosphorus after repairing.The potential use of beer wastewater as an external carbon source to solve problems with carbon deficiency and to estimate the efficiency of nitrogen and phosphorus removal in an anaerobic-anoxic-oxic (A2/O) process is investigated in the laboratory. It was found that the removal efficiency can be substantially changed by the addition of different doses of external carbon. Chemical oxygen demand (COD) values of0mg/L,30mg/L,50mg/L,70mg/L,90mg/L, and110mg/L produced nitrogen removal efficiencies of57.98%,68.57%,81.11%,82.39%,54.32%, and40.56%, respectively. For phosphorus they were75.87%,74.59%,73.69%,72.25%,70.74%, and69.31%, respectively. As a comparison, at a COD of70mg/L, which was found to be the best dosage of the external carbon, the efficiency of nitrogen removal was higher than that without the external carbon source by about24.41%. On the other hand, the efficiency of the total phosphorus removal was just lower (about3.62%) than without the external carbon source. The results show that beer wastewater can be an economical and effective external carbon source for enhancing nitrogen and phosphorus removal.By adding different concentrations of beer wastewater as external carbon to shock A2/O system and restoration this system by adjusting process parameters were aimed to compare the removal efficiency of nitrogen and phosphorus of the shock and further restoration. The results showed that the impact on the system was little by adding low concentration of external carbon source (COD=50mg/L) and helpful for improving the efficiency of nitrogen and phosphorus removal. When the addition dosage was COD=150mg/L, the removal efficiency of TN, NH4+- N, TP and COD were decreased by31.53%,16.38%,7.61%and10.19%, respectively. After the restoration these values had a decreased tend, compared to those before the shock. When the addition dosage was COD=250mg/L, the removal efficiency of nitrogen and phosphorus were significant decline, and produced a slight expansion of the sludge. After the restoration, the removal efficiency of TN, NH4+-N, TP and COD were decreased by11.75%,9.56%,21.2%,20.79%, respectively. Experiments showed that beer wastewater can be used as external carbon source for the adjustment system the C/N, and A2/O system had a certain resistance to the impact of the change in the concentration.