Experiment Of The Impact Of Humic Acid On Adsorption Of Copper Ion By Activated Sludge In SBR

Water contamination has been such a topic focused by the whole nation. The heavy metal in the sewage will affect the treatment process resulting in the deterioration of the water quality lately. Therefore, finding methods to solve heavy metal toxicity in sewage treatment plant seems bitterly urgent. Copper ion is a commonly poisonous substance in sewage which can be adsorbed by activated sludge; humic acid(HA) is also a common natural substance in the water. It can be adsorbed by activated sludge and absorbing heavy metal. While the copper ion can be absorbed by activated sludge and HA, changing the adsorption site of HA and activated sludge. Thus, the impact of HA on adsorption of copper ion by activated sludge in SBR is studied by various working conditions, continuing load and shock load in this study. And the changes of sludge activity, the content of polysaccharide and protein in EPS were analyzed, trying to explain the effect of HA on the removal of heavy metal by activated sludge in theory. The concentration of CODcr, ammonia nitrogen, HA in effluent, extracellular polymeric substance(EPS), TTC-ETS and SOUR are monitored to understand the impact of HA on adsorption of copper ion by activated sludge in SBR.The result of vrious working conditions shows that when HRT 20 h, SRT 20 d, 2mg/L copper ion, 10 mg/L HA are added in the SBR, the concentration of CODcr, ammonia nitrogen, HA, copper ion in fffluent of SBR is 23 mg/L, 0.2 mg/L, 0.12 mg/L and 0.089 mg/L, respectively. The removal rate is 92.65%, 99.42%, 95.00% and 95.55%, respectively. Under the effect of 10 mg/L HA, different concentration of copper ion(2-6 mg/L) had no significant effect on ammonia nitrogen and HA in the effluent of SBR. However, it has the opposite effect on the concerntion of CODcr and copper ion, which means the higher concentration of copper ion in the iffluent,the higher concentration of copper ion and CODcr in the effluent. In this test, the IC50 is 2.5mg/L; meanwhile, there is no signifcant connect between HA and ammonia nitrogen, HA, CODcr and copper ion.Under the optimal operating conditions, in the continuous operation with 2 mg/L copper ion and 10 mg/L HA, the continuous dosing of HA does not affect the water quality and active sludge. In the continuous operation of the SBR, the concerntion of CODcr rises firstly and then decreases. While the concentration of ammonia nitrogen and copper ion in the effluent increases continuously and reaches a stable level at the end of the experiment. What's more, HA can reduce the toxicity caused by copper ion and the polysaccharide and protein in activated sludge.Under the 5 mg/L copper ion shock loading, there is no significant effect on the concerntion of CODcr and copper ion in effluent. With the concentration of copper ions increasing 10mg/L, 20mg/L and 30mg/L, respectively, HA can reduce the concentration of CODcr and ammonia nitrogen in effluent of SBR. Furthermore, the concerntion of HA in effluent has no effect on the concerntion of HA in enfluet. It can reduce the change the concentration of dissolve oxygen(DO), polysaccharide and protein.The toxicity of copper ion on active sludge can also be reduced by adding copper ion in shock loading. The concentration of polysaccharide is decreased, while the concentration of protein is firstly increases, then decreases in recovery period.