PAPERmaking! FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 2, Number 1, 2016
The vermicompost was much darker in colour than before and has been processed more homogeneous mixture after 90 days of earthworm activity, the pH observed normal about 7.2 in the final vermicompost. Organic percentages were increased after composting for Set 1 it increased 36 % for Set 2; 35 % whereas for Set 3, it increased up to 50 %. The C:N ratio, one of the most widely used indicating for maturity of organic waste. In our experiments C:N ratio was between 9.4 and 18.4 after 90 days of worms activity. In Set 1, we observed 9:4; in Set 2, 13:4 and Set 3, 18:4. In initial stage, C:N ratio was 8:4 for Set 1, 9:3 for Set 2 and was 14:3 for Set 3. According to Senesi (1989) a decline of C:N ratio to less than 20 indicates an advanced degree of organic matter stabilisation and reflects a satisfactory degree of maturity of organic waste. Total K and N were also increased by the end of vermicomposting due to mineralisation of organic matter. Previously Benitez et al. (2000) has also reported that decomposition of organic materials by earthworm accelerates the N mineralisation process and subsequently changes the N profile of the substrate. Kaushik and Garg (2004) have reported a 2.0 – 3.2 fold increase in TKN during vermicomposting of textile mill sludge mixed with cow dung and wheat straw. Therefore, vermicomposting is a considerable technology for the waste or specially sludge to increase the soil nutrient condition. Different organochlorine contaminants like AOX and EOX in the sludge were analysed (described in Table 4). AOX values ranged from 451 to 5,140mg/kg dry solids. However, 93 – 95% decreases in the AOX and 90 – 92% decrease in EOX level, after composting which makes it less toxic more stable and reliable material for use. Earthworms accumulate many lipophilic organic pollutants from the surrounding soil environment not only through passive absorption through the body wall of the dissolved fraction in the interstitial water but also by intestinal uptake during the passage of soil through the gut. The accumulation increases as the concentration of the pollutant in the soil environment (Belfroid et al. 1995a, b).
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Article 2 – Treating Paper Mill Sludge
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