过氧化钙对黑臭水体中氮转化的影响及机制

Effect of Calcium Peroxide on Nitrogen Transformation in Black and Odorous Water Body and Its Mechanism

针对黑臭河道NH_(4)^(+)-N浓度难以降低的问题,采用过氧化钙(CaO_(2))原位封盖的方法修复模拟黑臭河道,考察不同CaO_(2)投加量下泥水体系的DO、氧化还原电位(ORP)、氮形态及浓度、沉积物中关键功能微生物等的动态变化。当CaO_(2)投加量为0.16 kg/m2(以沉积物计)时,水体的DO浓度高达7.9 mg/L,ORP由-44 mV升至108 mV,上覆水的TN和NH_(4)^(+)-N去除率分别可达到72%和94%。CaO_(2)导致泥水体系的DO浓度呈现时序性变化(好氧-缺氧-厌氧),高通量测序结果显示,当CaO_(2)投加量为0.16 kg/m^(2)时,第7天(DO>2 mg/L),亚硝化菌属(Nitrosomonas,2.51%)和硝化菌属(Nitrobacter,2.69%)可将NH_(4)^(+)-N转化为NO_(3)^(-)-N;第13天(0.5 mg/L<DO<2 mg/L),亚硝化菌属(Nitrosomonas,1.76%)可将NH_(4)^(+)-N转化为NO_(2)^(-)-N;第20天(DO<0.5 mg/L),热单胞菌属(Thermomonas,1.69%)、肠杆菌属(Enterobacter,2.48%)和Denitratisoma(0.32%)等反硝化菌可将NO_(3)^(-)-N和NO_(2)^(-)-N还原成氮气(N_(2))。研究结果表明,CaO_(2)可有效改善泥水体系的DO条件,导致脱氮微生物呈现动态变化,可恢复水体自净脱氮效能,通过硝化和反硝化作用实现生物脱氮过程,从而达到修复黑臭水体的目的。

The calcium peroxide(CaO_(2))in‑situ capping method was used to repair the simulated black and odorous river,and the dynamic changes in DO,ORP,nitrogen form and concentration,and the key functional microorganisms in the sediment were investigated under different dosages of CaO_(2),so as to solve the problem that NH_(4)^(+)-N was difficult to decrease in the black and odorous river channels.When CaO_(2)dosage was 0.16 kg/m^(2)(measured by sediment),the DO of water reached up to 7.9 mg/L,the ORP increased from-44 mV to 108 mV,and the removal rates of TN and NH_(4)^(+)-N from the overlying water reached 72%and 94%,respectively.CaO_(2)led to temporal changes of DO in the mud-water system(aerobic,anoxic and anaerobic).The high‑throughput sequencing results showed that Nitrosomonas(relative abundance of 2.51%)and Nitrobacter(relative abundance of 2.69%)converted NH_(4)^(+)-N into NO_(3)^(-)-N on day 7(DO was greater than 2 mg/L)when the dosage of CaO_(2)was 0.16 kg/m2.On day 13(DO was 0.5-2 mg/L),Nitrosomonas(relative abundance of 1.76%)converted NH_(4)^(+)-N into NO_(2)^(-)-N.On day 20(DO was less than 0.5 mg/L),denitrifying bacteria such as Thermomonas(relative abundance of 1.69%),Enterobacter(relative abundance of 2.48%)and Denitratisoma(relative abundance of 0.32%)reduced NO_(3)^(-)-N and NO_(2)^(-)-N to N_(2).CaO_(2)effectively improved the DO condition of the mud-water system,leading to the dynamic changes in denitrifying microorganisms,recovery of the self‑purification denitrification efficiency of water body,and occurrence of biological nitrogen removal through nitrification and denitrification,so as to achieve the purpose of black and odorous water body remediation.