Study on the Efficiency of a Hydroponic Treatment for Removing Organic Loading from Wastewater and Its Application as a Nutrient for the “Amaranthus campestris” Plant for Sustainability

Abstract

The investments needed for treating the wastewater produced by an ever-growing population has raised serious concerns regarding the environmental upkeep of many cities across the world. The concept of the circular economy in this context, i.e., the reuse of partially treated water to produce hydroponic plants, is the central idea of this paper. Usage of partially treated (secondary treated) wastewater for the growth of Amaranthus campestris is investigated. The many benefits here are the cost reduction in the treatment process, the reuse of water for commercial plants, the use of treated water, and no pressure on soil all address sustainable development goals such as zero hunger, no poverty, clean water, and sanitation. This study focuses on the degree of pollutant removal using Amaranthus campestris, a local green widely used in India. Secondary-treated domestic wastewater was fed to the hydroponic medium through batches by using an aerobic process, and the hydraulic retention time was maintained for 10 days. In addition to wastewater, a commercial hydroponic solution was added. This study was carried out to verify the reduction in organic loading in wastewater and the growth of plants in comparison with commercial hydroponic solutions. The total COD and BOD removal was significant (p < 0.0009), ranging from 58.5% to 72.5% and 80% to 82.5%, respectively, from the 0th day to the 50th day. After treatment, the lowest nitrogen, potassium, and phosphorus values in DWW were 2.4 mg/L, 5.4 mg/L, and 0.41 mg/L, found on the 20th, 30th, and 40th days of the experiment, respectively. It was also proven that the treated wastewater from the outlet of the hydroponic reactor was within the standard limits and safe to discharge into water bodies. Based on these results, it is encouraging to implement this method at a large scale in small local communities at a lower cost because of its simplified design in promoting a water-based circular economy, which has been proven to reduce carbon footprints, thus supporting a green environment.