Reduction of nitrogen content in landfill leachate using microalgae

Abstract

Landfill leachate contains large amounts of biodegradable or refractory to biodegradation organic materials, where organic and inorganic salts, ammonianitrogen, heavy metals and chlorinated consist important groups. Leachate from run out municipal landfills has a lower BOD5 but still high contents of N-NH4+. Usually, the ammonium concentration could be reduced by nitrification processes followed by biological denitrification, but for leachate from run out landfills this step requires the addition of organic molecules (e.g. methanol or acetic acid) as carbon source. To overcome this drawback, the authors suggested the use of mixotrophic microalgae to reduce the nitrogen content from landfill leachate before and after nitrification processes. In fact, microalgae could potentially offer many advantages in leachate treatment, being able to use inorganic nutrients for their heterotrophic growth without an aerobic environment. Microalgae cultures were performed with different quantities of landfill leachate after microfiltration pretreatment in order to have different nitrogen concentrations in water. Additional runs were performed in landfill leachate after biological nitrification pretreatment. Runs were compared with those carried out in classic Bold Basal Medium taken as a control. During the growth, biomass was observed microscopically and the ammonium, nitrate, nitrite contents were determined.

A Review of Landfill Leachate Treatment by Microalgae: Current Status and Future Directions

“…As mixing conditions, DO, temperature, surface area to volume ratio and the inoculation of wild bacterial/algal culture can impact the real-life application of algal-based remediation methods, therefore, small-scale, controlled lab studies seldom provide results which can be representative of real conditions. Casazza et al (2018) [32] studied the use of microalgae (C. vulgaris) to reduce the nitrogen content from leachate both before and after nitrification. Leachate was microfiltered to remove suspended solids.…”