Reagent-based treatment of domestic wastewater for ammonium removal in decentralized Arctic settlements

Decentralized Arctic settlements are equipped with modern water supply systems, yet they increasingly face the challenge of collecting and treating domestic wastewater. The study examined physical and chemical methods for treating domestic wastewater, similar in composition to wastewater from small northern settlements, with the goal of replacing the often inefficient biological treatment step, especially for organic substances. Wastewater samples at normal (18–22 °С) and extreme (3–6 °С) temperatures were treated in the laboratory using various technological schemes. As a result, the authors propose the most effective technological scheme for treating domestic wastewater in remote Arctic settlements, which includes the following stages: pre-aeration, sedimentation with coagulation and flocculation, chemical oxidation and struvite precipitation, and mechanical and sorption filtration. It was found that this technology is largely independent of water temperature and suitable for domestic wastewater with temperatures ranging from 3 to 22 °С. The implementation of this scheme reduced the concentration of ammonium ions by 96.5 %, suspended solids by 98 %, and chemical oxygen demand by 91 %. The proposed wastewater treatment scheme will simplify the operation of treatment plants in challenging Arctic conditions and enable their operation in automatic mode.