| In recent years,due to the rapid development of China’s economy,China’s water pollution has become very serious,which has become an important problem that restricts China’s economic development and affects people’s lives.Therefore,controlling water pollution in the body is particularly important.In this paper,the biological cover layer is mainly used for in-situ remediation of contaminated sediment,and the pollutants are treated harm Lessly.In this paper,we use two different signaling molecules,N-(3-oxohexanoyl)-L-homoserinelactone(OHHL),N-(β-Ketocaproyl)-DL-ho moserine lactone(C6),to enhance the enrichment of bacteria on zeolite.The effect of nitrification and denitrifying bacteria on the in-situ regenerating ability of bio-zeolites was determined by measuring the zeta potential of the bacterial layer of the membrane-coated zeolite,the change of extracellular polymer(EPS)and the FISH picture of the bacteria.The mechanism of enriching denitrifying bacteria in order to improve the in-situ regeneration ability of bio-zeolite and achieve the purpose of continuously repairing contaminated sediment.The results show:(1)C6 can significantly increase the enrichment ability of nitrifying bacteria WGX10、WGX18 and denitrifying bacteria HF3、HF7、WGX15 and HAT5 on zeolite,and the signal molecule OHHL effect is second.When the C6 concentration is 2.0μM when the bacterial liquid combination is WGX10、WGX18、HF3、HF7,the maximμM amount of bacteria attached to the zeolite is 0.03g/g.When the bacterial liquid combination is WGX10、WGX18、WGX15、HAT5,the C6 concentration is 1.0 μM,the maximμm amount of bacteria attached to the zeolite was 0.033 g/g.(2)When the bacterial liquid combination is WGX10、WGX18、HF3、HF7,in situregeneration of low ammonium zeolite(0.787 mg/g、1.557 mg/g、2.275 mg/g)when C6 concentration is 2.0 μM alone the higher rate is 42%-71.38%.When the bacterial liquid combination is WGX10、WGX18、WGX15、 HAT5,the low ammonium adsorption zeolite(0.787mg/g、1.557mg/g、2.275mg/g)is added when the C6 concentration is1.5μM.The in-situ regeneration rate of mg/g)is 34%-80%,and the in situ regeneration rate of high ammonium adsorbed zeolite(2.866 mg/g、3.511 mg/g)is 30%-39%.When C6 and OHHL are simultaneously added,the effect is not obvious.(3)The signal molecule increases the zeta potential of the bacterial surface,thus increasing the amount of bacteria attached to the zeolite.The signal molecule affects the EPS of the bacteria,and increases the concentration of the tryptop Han aromatic protein and the tyrosine aromatic protein in the EPS,thereby improving the adhesion of the bacteria and enhancing the adhesion of the bacteria to the zeolite.It can be seen from the FISH picture that the proportion of denitrifying bacteria in the total bacteria increases after the signal molecules are added.(4)Through two sampling analysis of polluted rivers,the dissolved oxygen concentration is inversely related to the ammonia nitrogen concentration,and the sediment has a tendency to release ammonia nitrogen upwards.(5)The results of the two-wheel sediment experiment show that the enriched nitrification and denitrifying bacteria on the zeolite can continuously repair the contaminated sediment.When the concentration of the signal molecule C6 is 1.5μM,the concentration of the ammonia nitrogen in the overlying water can reach the class III.Water quality standards.And the zeolite modified by Nacl is more effective.(6)The signal molecule C6 can effectively increase the adhesion of the nitrifying and denitrifying bacteria on the zeolite,so that the coating of the zeolite is continuously repaired to the sediment.After the first round of experiments,the biological removal rate of the signal-enhanced natural membrane-coated zeolite coating system can reach75%,and the modified zeolite can reach 76.34%.After the second round of testing,the natural zeolite bioremoval rate can reach 53.83%.The modified zeolite can reach58.61%. |
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