Pilot-scale Study On Two Phase Anaerobic Processes For Tannery Comprehensive Wastewater Treatment

This thesis is based on "tannery cleaner production and key technology research and demonstration for wastewater treatment subproject", which belongs to "National water special project-treatment technology research and integrated demonstration project for water pollution in Huai River". A pilot-scale treatment system which is on the basis of tannerty comprehensive wastewater treatment combined technique was constructed in demonstration enterprise "Xinwan tannery limited company" in Anhui Province and relevant systematic pilot-scale research was also carried out. Because of common problems,for example, lots of toxic chemical sludge is produced and high sulfate concentration isn’t able to be disposed effectively, which can be found in existing tannery comprehensive wastewater treatment technology,"hydrolytic acidification+anaerobic filter" two phases anaerobic process was designed and adopted in pilot-scale research. H2S gas reduced by sulfate flows into absorption tower and is converted into NaHS by NaOH which can be recycled in unhairing process, by utilizing acidic environment produced through hydrolytic acidification of high concentration macromolecule organic matters and internal cycle of gas. Effluent in hydrolytic process flows into anaerobic biofilter in order to remove COD and sulfate further. At the same time,by hydraulic jet sludge can be eliminated from filter material quickly, which improves biofilm activity and prevents filter clogging simultaneously.Research results of pilot project indicated that when technological parameter of hydrolytic acidification process is adjusted to6.3-6.6in pH,20-25℃in temperature,6.1h in hydraulic retention time,50%in sludge return ratio,4.8-6.4m3/(m3·h) in fan aeration ratio, parameter of anaerobic filter is adjusted to7.2-7.5in pH, fluidic device is initiated10minutes every2hours, pilot project achieves the most satisfactory results in terms of removal rate of CODCr and SO42-. In hydrolytic acidification process, average removal rate of CODCr and SO42-can reach45%,65%respectively while average removal rate of CODCr and SO42-in anaerobic bio filter reaches60%and40%, making the total removal rate of CODCr and SO42-up to70-80%. With influent concentration of CODCr ranging from3000mg/L to4000mg/L,SO42-ranging from1000-1500mg/L, effluent concentration of CODCr is lower than1000mg/L, effluent concentration of SO42-varies from200-300mg/L, S2-concentration in effluent is lower than100mg/L. Achievements from pilot-scale research offers powerful technical support for renovation of tannery comprehensive wastewater disposal system in demonstration enterprise.