Evaluation of Various Solid Wastes as Potential Carbon Sources for the Remediation of Nitrate Contaminated Water: Preliminary Results

ABSTRACT Nitrate contamination of groundwater is a major concern in the regions that depend on on‐site sanitation units, such as pit toilets. In situ biological denitrification employing solid phase denitrification is an attractive treatment solution for mitigating nitrate contamination. The availability of low cost solid organic carbon sources is crucial for effective in situ solid‐phase denitrification. The present study addresses this gap by assessing the nitrate removal potential of three solid waste substrates—cattle manure, peanut shell, and orange peel. The maximum nitrate removal efficiencies with cattle manure, peanut shell, and orange peel correspond to 99.1%, 78.8%, and 73.5%, respectively. The formation of intermediate nitrite ions and the presence of denitrifying bacteria in the batch samples suggest the probable occurrence of heterotrophic denitrification. First‐order kinetics of batch experiments revealed that nitrate removal with cattle manure was rapid compared to that with the other two carbon sources. A nitrate removal efficiency of more than 85% was achieved at varying initial nitrate concentrations (100–500 mg/L) using cattle manure as a carbon source. Utilization of these waste materials for the remediation of nitrate‐contaminated water contributes to a circular economy by converting low value waste into valuable bio‐resources for sustainable water treatment.