Study of use of pumice stone with sequencing batch reactor for treatment of dairy industries wastewate

Dairy industries generate a large amount of wastewater that contains high concentrations of carbonaceous and nitrogenous organic materials. Discharge of these wastewaters as untreated into environment leads to serious contaminations. The aim of this study was to evaluate the effectiveness of pumice stone application with sequencing batch reactor to remove organic compounds in dairy wastewaters. In this experimental study which was conducted at bench scale, two processes of sequencing batch reactor, conventional and equipped with pumice stone, were used as treatment models. In commissioning phase of systems, the sludge of municipal wastewater treatment plant underwent acclimatization for 9 days. Then, each reactor was inoculated with 2.5 liters of the sludge. In operation step, the reactors were continuously monitored for 36 days and the efficiency of the system for the removal of chemical oxygen demand (COD), biochemical oxygen demand (BOD5), proportion of total solids (TS) and total Kjeldahl nitrogen (TKN) was measured. The mean removal efficiency of COD, BOD5, TS and TKN was respectively 61.8±9.4, 58.5±8.6, 64.9±2.5 and 46.5±22.5 for the reactor without batch and 67.5±9.4, 63.4±11.8, 66.7±3.2, 62.2±15.7 for the reactor equipped with batch. By these results, removal efficiency of COD and TKN by the batch-equipped system had a significant difference from removal efficiency of these parameters by the system without batch (p<0.05). This study demonstrated increased removal efficiency of COD, BOD5, TS and TKN in sequencing batch reactor when pumice stone is used as microbial growth batch in reactor. This model could be considered as a suitable choice for treatment of dairy wastewaters.