ALLODUST augmented activated sludge single batch anaerobic reactor (AS-SBAnR) for high concentration nitrate removal from agricultural wastewater

Nitrate is among the most widespread contaminants that threaten water bodies and waterways. Under favourable environmental conditions, high nitrate concentrations in water can contribute to eutrophication, thus presenting a high potential for risk to ecosystems and human health. Low-cost allophanic soil material and carbon-based bio-wastes have great potential to reduce nutrient concentrations from contaminated waters. This study investigated the mechanisms that underpin the reduction of nitrate concentrations and nitrous oxide (N2O) emission in the presence of novel developed media in an activated sludge process. A new operating approach, employing a newly developed media (ALLODUST), was evaluated for enhanced NO3--N removal from agricultural wastewater. Two anaerobic-aerobic batch reactors were developed, where the coupled bottom aeration method was used for efficient agitation and aeration in the aerobic reactor. The reactor was run at high NO3--N concentrations (110 mg L-1), under anoxic conditions at low- to long-term contact times (2, 12, and 22 h), while the aerobic period (clarification) was constant for all the experimental designs (2 h). ALLODUST retained its integrity and stability over the long-term operation. Low ALLODUST concentrations (5.95 g L-1) removed 87% of the NO3--N from the wastewater within 12 h. Further exploration revealed that the same amount of the media was optimal for decreasing N2O emissions from the anaerobic activated sludge reactor by 80%. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

Nitrate contamination is a significant threat to water bodies, but low-cost materials like allophanic soil and carbon-based bio-wastes have shown potential in reducing nutrient concentrations. A new media called ALLODUST was evaluated for enhancing nitrate removal, with promising results in reducing both nitrate concentrations and nitrous oxide emissions. The study demonstrates the efficiency of the new operating approach in wastewater treatment and environmental protection.