Study On Bio-drying Of Paper Mill Sludge

In recent years, with the rapid development of our country's paper industry, water ollution problems came out. As the wastewater treatment rate and depth of our country's ulp and paper industry increaseing, paper making sludge production increased dramatically, 'aper mill sludge (PMS) was a complex composition of waste, and it was difficult to treat, "he treatment of PMS trended to be quantitative reduction, harmlessness and resource. The armless treat of PMS had become an urgent environmental problem.Sludge bio-drying could be definited as follow:it biodegradated the organic matter of ewatered sludge, speeded up the water loss of sludge, and produced dried sludge with lower loisture content (MC), under the condition of high temperature. With the treatment of io-drying, PMS could be using as agricultural additions, and dealing with incineration and andfill. The microbial metabolism for the bio-drying process was similar to that for the omposting process. However, the former aimed at the water removal, while the latter ocused on the bio-stabilization and maturity of composted materials.Thermophilic strainl#,2#,3# and 4# were purified from composting sludge, 'hermophilic strain 2# was screened as the inoculant for bio-drying process of PMS, by omparing their effect to the reduction of moist content of paper mill sludge, determinating f their growth curve and the most appropriate growth temperature. The identification of train #2 was as follows:the 16S rDNA sequence of strain 2# and Geobacillus hermodenitrificans was 100% homologous, and the morphological, physiological and iochemical characteristics of strain 2# were most similar to Geobacillus hermodenitrificans.The bio-drying characteristics of PMS and its influencing factors were investigated in a elf-designed experimental equipment. The following factors, such as temperature, pH value, MC, volatile solids (VS), ATP content, and quantity of amylolytic bacteria and so on, were elected as the main factors to study the raw material mixture ratio and parameters during the (?)o-drying treatment process. Sawdust, starch, potassium phosphate monobasic and noculation were selected as the factors of the orthogonal experiments. The evaluating index (?)f orthogonal experiments was the reduction of PMS. The range analysis of orthogonal xperiments indicated that the order of the factors was:starch>sawdust>inoculation> (?)tassium phosphate monobasic. The optimal process parameters of bio-drying of PMS were s followings:starch (25g/500g), sawdust (40g/500g), inoculation (15.0mL/500g) and potassium phosphate monobasic (5g/500g), and the continuous ventilation rate was 0.056m3/(kg-h) and the materials were manually turned every 2 days. Bio-drying could be an effective treatment for the further dehydration and reduction of PMS. After the bio-drying, the MC and VS of materials were reduced by 11.9% and 8.9%. It provided more choices for the follow-up treatment or use of PMS. The factors, including the temperature, pH value, MC, VS, ATP content, and quantity of amylolytic bacteria could be interpreted as the evaluating parameters of the bio-drying of PMS. The temperature of bio-drying materials could quickly attain 47.8℃on the optimized condition, and with a bio-drying period of 7 days, the output MC and VS could reduce to 50.3% and 49.5%, respectively.