Microbial osmotic pressure desalination system for desulfurization wastewater from coal-fired power plants: A pilot study

Abstract

The treatment of desulfurization wastewater has emerged as a critical area of research due to the significant water consumption and drainage volume associated with thermal power plants, which account for 30 %–40 % of industrial water usage. The desalination and treatment of this wastewater generate desulfurization byproducts, posing environmental risks and incurring high operational costs. This study established a pilot-scale desalination system based on the principle of microbial osmotic pressure for the treatment of desulfurization wastewater from power plants. The desulfurization wastewater primarily contains Cl−, SO42−, Mg2+, Ca2+, and Na+ ions. The microbial osmotic pressure device reduced the water conductivity from 26,000 μs/cm to below 8000 μs/cm, achieving a total salt removal rate of 70 %. The removal rates for Cl−, SO42−, Mg2+, Ca2+ and Na+ were 69.10 %, 76.55 %, 73.0 %, 35.34 % and 52.80 %, respectively. The desalinated water from the osmotic pressure device then undergoes aerobic removal of organic compounds, followed by membrane filtration and reverse osmosis for further desalination. The effluent conductivity is <1000 μs/cm, meeting the standards for reuse water. The microbial osmotic pressure device enriched salt-absorbing halobacteria and was dominated by norank_f__Bacteroidetes_vadinHA17, Trichococcus, Acidovorax, Soehngenia, and norank_f__Hungateiclostridiaceae. Compared to traditional processes, the biological desalination process demonstrates lower operational and annual maintenance costs under conditions of regular addition of microbial agents and liquid activators to sustain the desalination bacterial community. Future research could focus on desalination microbial cultivation methods to improve stability and reduce costs.