Anaerobic Degradation of Dairy Milk Wastewater

Abstract

Large amounts of wastewater generated during cleaning and washing in the milk processing unit of dairy industry result in land and water pollution unless treated properly before its discharge. The aim of the present study is, therefore, to find optimal conditions at which the pollution may be reduced quickly. Statistical analysis of COD removal efficiency data generated under the optimal conditions along with study of milk degradation reaction kinetics may help in deciding the reactor configuration for a pilot scale study. The degradation reaction kinetics of synthetic milk was carried out under the optimal conditions in a batch anaerobic reactor with seeds and with seed + PVC. This helped in designing a laboratory scale recirculating anaerobic baffled batch reactor (RABBR). Experiments were performed in RABBR fabricated out of PERSPEX sheet and two reactor configurations i.e., without partition and with partition were tested in the laboratory. It was observed that the COD and BOD removal efficiency improved with the addition of partitions. newlineThe experimental data were generated by varying parameters namely, temperature, organic loading , retention time under anaerobic conditions with/without seeds/PVC in the batch reactor operated at pH of 7.0. The biochemical oxygen demand (BOD3 at 270C) and chemical oxygen demand (COD) were determined as per standard procedure described in Standard Methods of Water and Wastewater Testing. COD removal at two different experimental conditions such as with added seeds and with added seeds along with PVC were recorded. The results show the dependency of BOD and COD reduction on organic loadings, retention time, and temperature, for the three different cases: without added seeds, with added seeds and with added seeds along with PVC. The percentage reduction of BOD and COD increased monotonically with organic loading and retention time in three temperature ranges i.e., psycophilic, mesophilic and thermophilic. The added seeds were found to reduced the time of treatment because ...