The Research Of Physico-Chemical Properties Variation Of Large Scale Aerobic Paper Sludge Composting And Its Land Application

Pulp and paper mill sludge was biosolid waste. The paper industry generatesa large number of sludges from the paper making processes. The sludges can bedivided into several categories: The primary sludge coming from the productionof virginwood fiber; The de-inking paper sludge produced by removing inksfrom post-consumer fiber; The secondary sludge (activated sludge) from thesecondary treatment systems sludge; And the combined paper sludge which ismixed the primary sludge with the secondary sludge.Composting can be an effective strategy to stabilize the sludge and reduce itsenvironmental risk prior to land application. The composting processbiologically stabilizes heterogeneous raw paper sludge and reduces mass andvolume and thus hauling costs. The technology of aerobic pulp and paper sludgecomposting on a large scale was studied. Composting could potentially reducethe C: N ratio and odor of sludges, composting of pulp mill sludge and woodshaves was made in forced-aeration static pile system, and changes oftemperature, oxygen, moisture and content of volatile substance duringcomposting were analyzed. When the mixing ratio of sludge and wood shaveswas 10:1 (v/v) in large scale, the duration of the hermophilic phase was longenough to conform to the sanitary standard of the non-hazardous treatment ofpaper sludge. The composting process suggested by earlier reports could bedivided into three stages: temperature increasing stage, high temperature stageand temperature decreasing stage. It is same as paper sludge composting. The temperature of a composting mass depended largely on airflow. Turning ofstacks or forced aeration, as in environmentally controlled composting, couldcontrol temperature effectively. The temperature changing trends at the differentplaces in the composting piles were different. The temperature of the upper-layerwas higher than the temperature of under-layer at the high temperature stage.The oxygen consumption rate was the highest at the end of temperatureincreasing stage, and it decreased after the hermophilic phase. The moisture andcontent of volatile substance decreased during the whole composting period, andtended to be indeclinable eventually. They decreased 20.2% and 5.9%respectively at the end of composting process.During the composting process concentration of total N decreased significant,but concentration of total K and P are different. Content of total K increasedmore rapidly than the content of P in large scale composting. The content oforganic matter constantly decreased from 282.2g/kg to 249.6g/kg in large scalecomposting process. 11.6% of the organic matter in paper mill sludge wasdecomposed.Selected field yield and biological indicators at seedling stage and yield weremeasured the fertilizer efficiency, for assessment of paper mill sludge fromChenming Paper Making Industry Company (ShanDong province) by large scaleaerobic composting. Compound fertilizer of paper sludge was produced inCaUun Fertilizer Company, A field study undertaken on protectoratevegetable(Tomato) with paper sludge compound fertilizer at different rates. Theresults indicated that the effect on biological indicators at seedling stage andyield of tomato by apply paper sludge compound fertilizer was better than thetraditional base manure. But difference was not significant.