Study On In-situ Sulfur Enhancement Control Of Anaerobic Digestion Of Excess Sludge

With the increase of the urban population,the number of sewage treatment plants to be built up is also rapidly increasing.As a derivative in the sewage treatment process,the output of sludge has also been rising in recent years.At present,the more popular sludge treatment technology is anaerobic digestion,which can achieve the sludge stabilization while generating clean energy biogas to meet the sludge treatment and resource requirements.However,biogas generated from sludge anaerobic digestion contains a certain amount of hydrogen sulfide,which has hindered the utilization of biogas due to its toxicity and corrosiveness.Therefore,desulfurization before biogas utilization is very necessary.During the experiment,the sludge in a wastewater treatment plant in Xi'an was studied.Anaerobic digestion was carried out on sludge with different solids contents?2%and 10%respectively?,and the anaerobic digestibility While the sludge containing 2%solids and 10%solid content were respectively controlled for sulfur suppression in situ.When Fe???Sulfur in situ on the basis of its strengthening investment efficiency and were discussed.Concluded as follows:?1?Anaerobic digestion of conventional sludge and highly solidified sludge respectively showed that with the increase of solid content,the gas production increased,and the anaerobic digestion gas production of high solidified sludge was a normal one And the content of C,N,P and so on in the stable stage increases proportionally with the solid content as the solid content increases.However,the content of H₂S in biogas showed the opposite trend.The content of hydrogen sulfide in biogas after conventional sludge anaerobic digestion is higher than 2000ppm,and the content of hydrogen sulfide in biogas after anaerobic digestion of high solids sludge is much lower than that in biogas produced by anaerobic digestion of conventional sludge.?2?The study on anaerobic Sulfur-depressing of ammonia in tank by conventional anaerobic digestion of sludge found that the addition of ammonium chloride to the system did not affect the stability of the system,and the COD removal rate of the system increased after adding ammonia.However,after adding ammonia,the dissolved protein content of the system increased significantly,that is,properly increasing the concentration of ammonia nitrogen in the reactor is conducive to the conversion of macromolecules such as protein and protein in the reactor to the dissolved state.After adding ammonium chloride to the digestion reactor,The digestion reactor hydrogen sulfide removal rate was45.71%,high temperature anaerobic digestion reactor hydrogen sulfide removal rate of46.62%,indicating that the addition of Ammonium to the digestion reactor has a certain inhibitory effect on the formation of hydrogen sulfide.?3?The Sulfur in situ Sulfur Inhibition Test of Fe???in high solids sludge showed that when pH was 7.00-7.50 and Fe/S was 1-11,Increasing the digester pH will reduce Fe???dosage.The minimum Fe/S required for anaerobic digester with high solid content sludge to meet the H₂S use standard is 7.0.When the digester pH is below 7.30,it will not be able to pass Adjust Fe/S to achieve H₂S concentration discharge standards.?4?The results of anaerobic digestion of Fe???in situ with high concentration of solid anaerobic digestion indicate that the addition of Fe???to Zn???or Cu???.Sulfide removal efficiency was optimized from 0%⁴0%before dosing to 20%⁷0%.That is,Zn?II?and Cu?II?are more efficient in inhibiting sulfur in situ relative to Fe?III?.During the test it was found that at the Cu/S=0.5,the Fe/S required for the same dissolved sulfide removal was the least,about 1.5.This is a 5-fold reduction in the Fe?III?dosage compared to the previous Fe/S required to achieve H₂S compliance emissions of at least 7.75.