PhD Oral Defence: Use of hydrogel based soil amendments to promote safe use of wastewater in agriculture
PhD Oral Defence of Jaskaran Dhiman, Bioresource Engineering
Increased food production, required for an increasing population, would place additional stress on our freshwater resources. Since agriculture is the largest freshwater consumer, supplementation of irrigation water with wastewater could be beneficial. However, wastewater contains contaminants like heavy metals, which could be taken up by food crops and/or contaminate groundwater. To reduce heavy metal mobility (Cd, Cr, Cu, Fe, Pb & Zn) in soil and deter their uptake by potatoes (Solanum tuberosum L.) and spinach (Spinacia oleracea L.) irrigated with synthetic wastewater, polyacrylamide superabsorbent polymer (SAP) and a mixture of SAP and plantain-peel biochar (SAP+BC) soil amendments were tested. The study was carried out in field lysimeters (PVC cylinders; 1.00 m x 0.45 m ID) packed with sandy soil. The amendments were mixed in soil, at an application rate of 1% (w/w). All the treatments were replicated thrice, in a completely randomized design for each crop. It was found that use of SAP and SAP+BC soil amendments can lead to reduced uptake of heavy metals by wastewater irrigated crops (both underground and aboveground) grown on sandy soils, as well as reduce heavy metal mobility in the soil. Thus, use of hydrogel based amendments in soil could promote safe use of wastewater for irrigating crops, especially in developing countries.