Treatment of acidic sulfate-containing wastewater using revolving algae biofilm reactors: Sulfur removal performance and microbial community characterization

Abstract

Industries such as mining operations are facing challenges of treating sulfur-containing wastewater such as acid mine drainage (AMD) generated in their plant. The aim of this work is to evaluate the use of a revolving algal biofilm (RAB) reactor to treat AMD with low pH (3.5-4) and high sulfate content (1-4 g/L). The RAB reactors resulted in sulfate removal efficiency up to 46% and removal rate up to 0.56 g/L-day, much higher than those obtained in suspension algal culture. The high-throughput sequencing revealed that the RAB reactor contained diverse cyanobacteria, green algae, diatoms, and acid reducing bacteria that contribute the sulfate removal through various mechanisms. The RAB reactors also showed a superior performance of COD, ammonia and phosphorus removal. Collectively, the study demonstrated that RAB-based process is an effective method to remove sulfate in wastewater with small footprint and can be potentially installed in municipal or industrial wastewater treatment facilities.

Microalgae wastewater treatment: Biological and technological approaches

“…The authors found a 302% increased biomass productivity compared to control raceway ponds yielding a biomass productivity of 18.9 ash free g m −2 d −1 , which was further increased to 46.8 g m −2 d −1 by using a trough-based RAB configuration [132]. Zhou and co-workers validated the RAB system processing sulphate-loaded mining wastewater at low pH conditions obtaining a sulphate removal efficiency of 46% with a rate of 0.56 g L −1 d −1 [133]. A further RAB validation study at pilot scale was performed at supernatant from sludge sedimentation yielding removal rates of 80% (total P) and 87% (total N), respectively.…”

Assessment of Chlorella vulgaris, Scenedesmus obliquus, and Oocystis minuta for removal of sulfate, nitrate, and phosphate in wastewater

“…Sulfate is the most common form of sulfur in wastewater. Although sulfate is inoffensive to the environment, the activities of sulfur reducing bacteria present in wastewater sources lead to production of sulfide, which has higher toxicity, corrosivity, and an offensive odor, and also is deleterious to human health [10]. Therefore, effective and efficient removal of sulfate from wastewater becomes important.…”

“…Sulfate in wastewater can be removed by physical, chemical, and biological means. The high-energy requirements of physical methods like ion exchange and membrane filtration [10], and excessive chemical requirement for precipitation make these options less attractive. The biological removal by use of sulfur reducing bacteria has the demerit of releasing hydrogen sulfide to the atmosphere, which can be difficult to maintain anaerobic conditions as required for this method.…”

Removal of total dissolved solids from wastewater using a revolving algal biofilm reactor

“…The removal of different ion species in algal culture may be due to the cation transport through the cell membrane, adsorption, and chemical precipitation (Malik, ). Algae have been reported notable capabilities of removing ions such as sodium, calcium, magnesium, potassium, and sulfur through biosorption (Wang et al, ; Zhou, Sheng, Zhao, Gross, & Wen, ). Zhou, Min, et al () reported 92% removal of calcium, and 20% removal of sodium, potassium, and sulfur through bio‐assimilation and precipitation.…”

“…As for sulfur content, the results from sulfur removal from different wastewaters (Figure ) and sulfur accumulation in biomass (Table ) indicate that biofilm algae in RAB reactors can absorb more sulfur than the suspended algae in BC reactors. The superior capability of assimilating sulfur by the RAB algae was probably due to the physical adsorption by the EPS (Kesaano & Sims, ; Zhou et al, ).…”