| Straw-washing wastewater discharged from straw based pulping andpapermaking contains high concentration of COD, SS and high colourity, whose OLR(organic loading rate) account for50～60%of the total organic loadings in strawbased pulping and papermaking. The effective treatment and reuse of straw-washingwastewater is the crucial step to make the whole treatment operate steadily, and todecline the effluent concentration and the cost of disposal further.This paper discussed the treatment of straw-washing wastewater by anaerobicgranular sludge and anaerobic flocculent sludge, and analysis the results from COD、SS and VFA etc. Determined which sludge is more suitable for treating straw-washing wastewater. Conclusions were as follows from experiment:When treating the straw-washing wastewater by anaerobic granular sludge andanaerobic flocculent sludge, the rate of BOD5and COD in wastewater was greaterthan0.3, explaining straw-washing wastewater has some biodegradability. But it wasgeneral. Besides, the C:N:P of straw-washing wastewater was also in (200to350):5:1, fully meeting the needs of the anaerobic reaction.During the experiment, when the reactor ran well by anaerobic granular sludge,the volume loading was6.93～8.19kg COD/(m3·d) and the COD removal rate was33.00～42.35%, average39.33%; when the reactor ran well by anaerobic flocculentsludge, the volume loading was4.64～6.57kg COD/(m3·d) and the COD removalrate was8.29～38.33%, average24.79%. Seen from the experimental results in termsof COD removal efficiency, Treatment effect of anaerobic flocculent sludge wasbetter, and the volume loading was bigger when reactor running.When treating the straw-washing wastewater by two kinds of sludge, the effluentVFA was higher, the pH value was lower; the effluent VFA was lower, the pH valuewas higher. During the experiment of anaerobic granular sludge, the effluent VFAhad been high. Although reactor was adjusted by adding alkali, the effluent VFA wasstill higher than normal. The COD removal rate was only24.79%. After thedomestication period of anaerobic flocculent sludge, the effluent VFA was normal and the COD average removal rate was39.99%. NO adjusting by adding alkali inexperiment, the effluent VFA had been accumulated continuously, and reached758mg/L finally. The COD removal rate was down to the sludge domestication stagelevel.The aspect of SS removal rate treating the straw-washing wastewater by twokinds of sludge: When anaerobic flocculent sludge treating straw-washing wastewater,the data was from ten days of reactor running well, granular sludge select thecorresponding to the inlet COD in2000mg/L for more than10days of data. Thewater quality of anaerobic flocculent sludge was stability, the SS removal ratechanged little, fluctuations in64.69%～70.87, average67.62%; In the experiment ofanaerobic granular sludge, enterprises cannot be normal production, leading to largerchanges in water quality. So the SS removal rate also follow changed, the lowest was51.28%and the highest is76.53%, average60.14%. Judging from the experimentaldata, the SS removal effect of anaerobic flocculent sludge was better than anaerobicgranular sludge.When treating straw-washing wastewater by both anaerobic granular sludge andanaerobic flocculent sludge, the concentration of effluent TN was higher than influentTN. This was because the reactor did not run well when treating straw-washing wastewater by two kinds of sludge. The activity of microbial was low,reducing the conversion of nitrogen in wastewater. The sludge autolysis also releaseda certain amount of nitrogen element, leading the concentration of effluent TNincreased. |
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