Influence of temperature and pH on nitrogen removal in a series of maturation ponds treating anaerobic effluent

This paper presents an evaluation of the influence of pH and temperature on nitrogen removal in a series of three shallow maturation ponds serving as post-treatment of upflow anaerobic sludge blanket (UASB) reactor effluent (approximately 200 population equivalent). Monitoring was from January 2007 to May 2009. Throughout this period, the ponds maintained relatively stable operational conditions in terms of depth and hydraulic retention time, thus enabling the evaluation of the influence of variations in temperature and pH on the performance in terms of nitrogen removal. In general, as expected, the removal of nitrogen was more effective when the temperature and pH of the ponds were higher, implying that these variables are relevant in the removal of nitrogen. Due to the fact that these parameters are included in the prediction equations for effluent ammonia and total nitrogen found in traditional models from the literature, fitting of the models to the experimental data was investigated. The models gave acceptable fittings in the estimation of effluent concentrations of ammonia and total nitrogen from maturation ponds treating UASB reactor effluent.