Effectiveness of Biochar and Zeolite Soil Amendments in Reducing Pollution of Municipal Wastewater from Nitrogen and Coliforms

Abstract

A greenhouse experiment with soil cores and wastewater application was carried out to investigate the effects of biochar and zeolite on the mobility of nitrogen and coliform bacteria during the leaching of columns repacked by a silty loam soil. Triticum aestivum plants were grown in cores with and without biochar and zeolite irrigated with municipal wastewater for 4 months in the greenhouse. Cores were then flushed with 800 mLof distillate water and, finally, the leachate was collected. Application of biochar or zeolite significantly (p ≤ 0.05) reduced nitrate and ammonium loss in soil after leaching process, compared to their non-treated counterparts. In addition, interactions of biochar and zeolite significantly decreased nitrate and ammonium content in leachate. Biochar had higher removal effects of coliform bacteria in leachate than zeolite. Lower nitrate and ammonium content in leachate was related to the increased retention of soil amendments. Application of 5% w/w of biochar also reduced the volume of leachate by 11% compare to control, but using 5% w/w and 10% w/w of zeolite increased the volume of leachate compared with non-treated columns by 21% and 48%, respectively. Taken together, these data highlight the need to consider the potential benefits of biochar and zeolite as soil amendment to reduce nitrogen mobility and remove coliform bacteria in the leaching process of municipal wastewater in agricultural systems.