Effect of Saline Water on Decomposition and Landfill Gas Generation of Municipal Solid Waste

Abstract

The fundamental process involved in the operation of bioreactor landfills is the addition of water and/or the recirculation of leachate into the landfill’s waste mass for rapid waste stabilization, waste decomposition, and increased rate of gas generation. However, operating a landfill as a bioreactor landfill requires the availability of a sufficient amount of fresh water in close proximity to the landfill facility. In coastal regions, where freshwater supplies may be scarce, available saline water can be considered for bioreactor operation. However, limited studies are available on the effect of using saline water for the biodegradation of municipal solid waste (MSW). The objective of the current research is to investigate the effects of adding and/or recirculating saline water for the biodegradation and landfill gas generation of MSW at the Cefe Valenzuela Landfill, Corpus Christi, Texas. To accomplish this objective, two sets of bioreactor cells were simulated in the laboratory. Each set of reactor consisted of two 22.7 L (6 gal.) reactors. The first set of reactors was filled with fresh MSW collected from the Cefe Valenzuela Landfill and operated with fresh water (control reactors); the second set of reactors was operated with saline water collected from the landfill site. To assess the effect of salinity on biodegradation, the composition and volume of generated gas and the pH of generated leachate were regularly monitored. According to the experimental results, the utilization of saline water for bioreactor operation may delay the methane generation of landfills. However, once the methane production starts, the gas generation rate and volume were similar to bioreactor operation using deionized water. Therefore, the addition of saline water for bioreactor operation is considered suitable for the Cefe Valenzuela Landfill at Corpus Christi, Texas.