Long-term effective remediation of black-odorous water via regulating calcium nitrate sustained-release

Abstract

Abstract Nitrate addition was reported as the cost-effective method for remediating black-odorous water, which was induced by the deficiency of electron acceptors. However, the excessive release of nitrate and nitrite and lack of long-term effectiveness caused by directly dosing nitrate method significantly limited its application. Herein, we constructed a nitrate sustained-release ecoN-concrete, in which calcium nitrate (Ca(NO3)2) was dosed in the concrete revetment, to remediate black-odorous water. Identically, chemical oxygen demand (COD), turbidity, ammonia, phosphates, and sulfate were significantly removed after loading black-odorous water into an ecoN-concrete-contained reactor, and its removal efficiency was largely dependent on Ca(NO3)2 dosage. Meanwhile, the released nitrate was only accounted for 25% of the total dosage and nitrite was lower than 1.5 mg/L via 14 days cultivation. After three recycles, the removal efficiencies of COD and turbidity by ecoN-concrete were still higher than 85% indicating this concrete was good at nitrate sustainable release and controlling water re-blackening and re-stinking in suit. Further investigation illustrated that the ecoN-concrete (1) decreased the abundance of Desulfovibrio, Desulfomonile, and Desulforhabdus in the phylum of Desulfobacterota to alleviate the odorous gases production, (2) significantly increased the abundance of Bacillus and Thermomonas, which utilized the released-nitrate to consume organic matters and ammonia. This study provided an artful Ca(NO3)2 dosing strategy and long-term effective method for black-odorous water remediation.