Coir rettng wastewater treatment using membrane bioreactor and anaerobic reactor combined with advanced oxidation process

Abstract

Freshwater is essential for human life and its quality has been a matter of global concern. Freshwater resources have been the solution for nearly all drinking and irrigation water problems. Wastewater containing high concentrations of microbiological contaminants cause reduction in overall crop yield and quality in addition to the contamination of crops by pathogens and intestinal helminths. However, high yield can be achieved using pretreated wastewater for irrigation purpose of various crops which in turn supplies the nutrients and organic wastes essential for plants and microorganisms in soil under controlled environmental conditions. Among the major hazardous pollutants, phenol and its compounds pose serious environmental issues due to its high water solubility and high toxicity. The disposal of phenol containing wastewater without proper treatment causes negative effects on the environment since it does not degrade easily. The effluents from major industries such as chemical, pharmaceutical, petroleum refineries, coal gasification operations, liquefaction process, resin manufacturing, dye units, pulp and paper mills contain phenol compounds. Phenol is a highly corrosive and nerve poisoning agent. Coir is one of the strongest natural fibres extracted from coconut husk which has been widely used all over the world. Open retting is an old practice for the extraction of coir which has been carried out in natural water bodies. Also it is the most important pollution creating process in the backwaters. Traditional coir defibering process is a natural biochemical process which involves coir retting. Retting results in the release of large quantities of organic substances like polyphenols and chemicals including pectin, pentosan, tannins, sulphide, phosphate, nitrate, hydrogen sulphide and ammonia. Hence, this results in an increased Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD). The effluents from coconut husk retting contain recalcitrant components like phenol which has been discharged in to pond or river This study focuses on the seasonal variation of physicochemical parameters of coconut husk retting wastewater samples. The physicochemical parameters such as pH, chemical oxygen demand (COD), Biological Oxygen Demand (BOD), phenol concentration, Total Solids (TS), Total Suspended Solids (TSS), total dissolved solids (TDS), colour and biodegradability of the wastewater samples were analysed. Most of the analysed parameters were found to be higher than the permissible limit prescribed by World Health Organization (WHO) and Bureau of Indian Standards (BIS) for water quality guidelines. newline