Utilization of moringa oleifera for reuse of treated domestic wastewater

Abstract

Rapid increase of population increases the freshwater demand. Domestic wastewater production increases worldwide. All over the world disposal of treated domestic wastewater into natural water bodies leads to degradation of aquatic life. Treated domestic wastewater could be considered as new water resources in many sectors such as agriculture. Wastewater may contain several harmful pathogens, heavy metals and other chemical species. Therefore, systematic monitoring of treated domestic wastewater is required before applying it for agricultural use. In this study, an initiative has been taken to characterize the treated domestic wastewater for its reuse in agricultural purpose. The characterized values (pH, BOD, DO, turbidity, alkalinity, hardness, residual chlorine, TDS, TSS, COD, total nitrogen, nitrate, sulfate, fluoride, Ca, Mg, Zn, Cu, Ni, Pb, As, Hg, Al, Na, SAR, Fe and K) were then compared with national (IS: 2490, 1981) and international (FAO, 1994) standards. It has been found that potassium (4.38 mg/l) does not fulfill the minimum requirement (5 mg/l) for agricultural use as per the international standard (FAO, 1994). Considering the reuse of this effluent for agriculture, it would be necessary to upgrade its characteristics to make the reuse sustainable and beneficial. To maintain the required nutrient within specified range, powder form of dried seed of Moringa oleifera (MO) was added into treated domestic wastewater. It was found that MO has great potential to fulfill the nutritional demand of treated domestic wastewater for agricultural use. In this study experimental optimization was done using DOE. Dissolution kinetics was also performed to know the factors affecting dissolution process of MO seed powder. It was found that the dissolution kinetics follow diffusion controlled shrinking core model (R2 =0.977) having 91.63 kJ/ mol of activation energy. It is an innovative study to use ecofriendly natural material to fulfill the chemical requirement of treated domestic wastewater for the agricultural purpose. This study is very much useful to make its reuse safe, minimizing fresh water demand and provide economical wastewater treatment technology.