Cost-effective bioregeneration of nitrate-laden ion exchange brine through deliberate bicarbonate incorporation.
Bioregeneration of nitrate-laden ion exchange brine is desired to minimize its environmental impacts, but faces common challenges, i.e., enriching sufficient salt-tolerant denitrifying bacteria and stabilizing brine salinity and alkalinity for stable brine biotreatment and economically removing undesired organics derived in biotreatment. Incorporation of 0.25 M bicarbonate in 0.5 M chloride brine little affected resin regeneration but created a benign alkaline condition to favor bio-based brine regeneration. The first-quarter sulfate-mainly enriched spent brine (SB) was acidified with carbon source acetic acid for using CaCl2 at an efficiency >80% to remove sulfate. Residual Ca(2+) was limited below 2 mM by re-mixing the first-quarter and remained SB to favor denitrification. Under [Formula: see text] system buffered pH condition (8.3-8.8), nitrate was removed at 0.90 gN/L/d by hematite-enriched well-settled activated sludge (SVI 8.5 ml/g) and the biogenic alkalinity was retained as bicarbonate. The biogenic alkalinity met the need of alkalinity in removing residual Ca(2+) after sulfate removal and in CaCl2-induced CaCO3 flocculation to remove 63% of soluble organic carbon (SOC) in biotreated brine. Carbon-limited denitrification was also operated after activated sludge acclimation with sulfide to cut SOC formation during denitrification. Overall, this bicarbonate-incorporation approach, stabilizing the brine salinity and alkalinity for stable denitrification and economical removal of undesired SOC, suits long-term cost-effective brine bioregeneration.
Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China; State Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110164, China.
Qi
Q
Li
Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China; State Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110164, China. Electronic address: huangbin@iae.ac.cn.
Bin
B
Huang
Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China; State Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110164, China.
Xin
X
Chen
Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China; State Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110164, China.
Yi
Y
Shi
D001639:Bicarbonates / Q000737:chemistry*; D002122:Calcium Chloride / Q000737:chemistry; D002244:Carbon / Q000737:chemistry; D058440:Denitrification; D007475:Ion Exchange Resins / Q000737:chemistry / Q000378:metabolism*; D009566:Nitrates / Q000737:chemistry / Q000378:metabolism; D009573:Nitrites / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D012492:Salts / Q000737:chemistry*; D012722:Sewage / Q000737:chemistry; D013431:Sulfates / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000378:metabolism*; D018508:Water Purification / Q000191:economics* / Q000379:methods*
D001639:Bicarbonates; D007475:Ion Exchange Resins; D009566:Nitrates; D009573:Nitrites; D012492:Salts; D012722:Sewage; D013431:Sulfates; D014874:Water Pollutants, Chemical; C017082:brine; D002244:Carbon; D002122:Calcium Chloride
Bacterial derivatives; Bicarbonate alkalinity; Brine reuse; Drinking water; Nitrate contamination