The Effect Of Anaerobic-aerobic On Adsorption Of Ca²⁺ By Activated Sludge

The effects of anaerobic conditions and aerobic conditions on the adsorption of Ca²⁺by activated sludge were studied in this paper.Two reactors,anaerobic bioreactor and aerobic bioreactor were set up to study the adsorption regularities of Ca²⁺by activated sludge,and high calcium wastewater was onself-matched by CaCl₂ in this research.We discussed the factors in the process by means of orthogonal text method.Experimental results showed the main influencing factor of the Ca²⁺adsorption by activated sludge was the pH of influent.Under the best adsorption process,the adsorption and removal of calcium ions were15.04%?anaerobic?and 13.73%?aerobic?.Based on the result of the orthogonal text method,we explored the effects of different influent pH for the index parameters of activated sludge.The results showed that with the increase of the pH of influent,the adsorption quantity of Ca²⁺by activated sludge increased while the pH value was less than 10.87.When the pH value was 10.87,the adsorption quantity reached the maximum,which could reach32.72mg/g?anaerobic?and 33.58mg/g?aerobic?,the removal rate could reach14.73%?anaerobic?and 15.12%?aerobic?.But high pH value of the influent?pH?13?,easy to cause the sludge disintegration,the release of COD and the content of EPS from sludge was reduced,so the adsorption quantity would reduce.Different pH of influent also had a significant effect on the concentration of polysaccharide from aerobic activated sludge of adsorption process.The kinetics and isotherms were fitted to the adsorbtion process of Ca²⁺on activated sludge,and infrared spectroscopy and scanning electron microscope?SEM?of the activated sludge were analyzed.The results showed that the anaerobic and aerobic reactors could be described by the second-order model during the process of the adsorption of calcium ions by activated sludge.The correlation coefficients R²were 0.9604?anaerobic?and 0.9960?aerobic?,respectively.Calcium ion adsorption experiments using activated sludge could be fitted by Langmuir equation model.The correlation coefficients R² were 0.9363?anaerobic?and 0.9726?aerobic?,respectively,and the maximum adsorption quantity q_m after fitting can be achieved71.4 mg/g?anaerobic?,50.00 mg/g?aerobic?.The analysis of infrared spectrum showed that groups of N-H?COO-?-OH?C-O-C in activated sludge were involved in the process of adsorption of Ca²⁺by activated sludge.SEM?SEM?showed that the calcium in solution was transferred to the sludge mainly by adsorption deposition.Based on the 16SsRNA gene-based Miseq sequencing method,the microbial community structure in pretreated activated sludge,the activated sludge of anaerobic adsorption and aerobic adsorption were analyzed,and its composition and dominant flora were analyzed.The test results showed that:23 gates and 151 genera were detected in the pretreatment group;30 gates and 206 genera were detected in the anaerobic group;29 gates and 167 genera were detected in the aerobic group;and the preconditioning group and anaerobic The group had significant differences in 12phylums and 61 genuses;the pretreatment group and the aerobic group had significant differences in 8 phylums and 18 genuses;the anaerobic group and the aerobic group had 10 gates and 19 aerobic groups.There is a significant difference in the genus;from the species richness point of view,the highest in the anaerobic group,the lowest in the pretreatment group,and the aerobic group were between the two,which showed that the adsorption process of Ca²⁺by activated sludge could increase richness of species.Three groups showed significant differences in Firmicutes,Bacteroidetes,Proteobacteria,Actinobateria,Cyanobateria,S accharibacteria.The Venn diagram of the common functional groups was analyzed,and the results showed that there was no change in the common functional microbiota of the anaerobic adsorption and aerobic adsorption.