Mixed greywater treatment for irrigation uses

Abstract

Water contamination comes from many different sources, including, among others, factories, sewage treatment plants, mining activities (heavy metals), food-processing waste, agriculture runoff, animal waste, disposal of personal care products, and household chemicals. Therefore, the reuse of wastewater has become a fundamental strategy for sustainable water management and maintaining environmental quality. In this sense, this research presents a simple and economic alternative to solving the problems caused by greywater, resulting from laundry activities. This paper evaluates a mixed system for the treatment of greywater. The mixed system has physical filters that are composed of river stone, concrete, river sand, and coal. A bioremediation technique is also evaluated, involving two types of aquatic plants, watercress (Nasturtium officinale L.) and duckweed (Lemma minor L.). This study showed significant differences in pH reduction, from 9.56 to 7.50, total suspended solids (TSS), from 1742.00 mg/L to 298.50 mg/L, phosphates, from 1.12 mg/L PO₄³¯ to 0.31 mg/L PO₄^3- , and chemical oxygen demand (COD), from 472.38 mg/L to 8.52 mg/L. Thus, the results indicate that this system is efficient for the reuse of grey water for irrigation uses. Moreover, each parameter, with the exception of dissolved oxygen and total suspended solids (TSS), meets the maximum limits set by the Environmental Quality Standards for Category 3: irrigation water for vegetables and animal beverages and the FAO irrigation water standards.