• Journal of Environmental Health Sciences
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• v.24 no.1
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• pp.112-119
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• 1998

The objective of this study was to investigate the effect of bulking agents including cow manure, saw dust and rice straw in the ripening of leather sludge for vermistabilization. The changes of the waste properties for ripening time for 50 days were observed according to the various mixture ratios of leather sludge and bulking agents. The pH values of the mixture wastes were decreased from 7.5-8.0 to 6.4-7.3 with the ripening time for 50 days, and it was indifferent of the mixture ratio and type of the bulking agent. The initial value of oxidation-reduction potential(Eh) of the mixture waste was a negative(-)value indicating an unfavorable condition for earthworm life, but the values of Eh were increased with the ripening time. The increase rate of Eh value was proportional to the mixture ratio of bulking agents, but the increase rate for saw dust was higher than that of the cow manure and the rice straw. The value of alkalinity was also changed into the favorable range for earthworm after 50 days except for 10% of the mixture ratio of the bulking agents. When the mixture ratios of the bulking agents were increased from 10% to 40%, the growth characteristics of earthworms were increased from 31.7% to 95% for the survival rate, 103% to 225% for the liveweight increase rate and 32% to 91% for hatching rate of the cocoons. It can be concluded that the proper content of the bulking agents in the leather sludge to ensure effective vermistabilization was over 30%, when the mixture was ripened during 50 days. The contents of heavy metals in the ripened sludge were lower than the other regulatory standards for compost.

• Resources Recycling
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• v.7 no.3
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• pp.52-57
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• 1998

The objective of this study was to investigate the effect of cow manure as additive material on the ripening of sewage s sludge for vermistabiJization. The changes of the waste properties by ripening for 50days were observed as a function of the v various mixture ratios of sewage sludge ‘and cow manure. The pH values of the mixture wastes decreased from 7.5-7.67 to 6_ 9~7.2 by the ripening for 50days, and the mixture ratio made dIfferent pH values. The initial value of oxidation-reduction p potential (Eh) of the mixture waste was a negative (-) value indicating an unfavorable condition for earthworm after, but the v values of Eh increased with the opening time. The Increase rate at Eh value was prop$\alpha$rtional to the mixture ratio of cow m manure. The value of alkalinity was also changed into the favorable range for earthworm after 50days except for non-use of 1 the cow manure When the mixture ratio of the cow manure increased from 10% to 30%, the growth of earthworms increased h from 63.7% to 88.3 % tor the survival rate, 265% to 321% for the liveweight increasing rate and 66.7_7% to 91% for hatching f rate of the cocoons. It can be concluded that the proper content of tbe cow manure in the sewage sludge to ensure effective v vermistabilization was over 20%, when the mixture was ripened during 50 days. The quantity of ingestion and 며ectian at 20%-30% was found to be O.15--i.L18g sludge and 0 1l--O.14g solid per capacity earthworm per day, respectively.

• Journal of environmental and Sanitary engineering
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• v.15 no.4
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• pp.91-97
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• 2000

The objective of this study was to evaluate the possiblity of Foodwaste and co-treatment with other waste for vermistabilization. The value of oxidation-reduction potential(Eh) of the dewaterized foodwaste by a plant of subatmospheric evaporation was a possitive(+) value indicating, but the values of pH, salinity was idicating an unfavorable condition for earthworm life. The paper mill mixing waste properties by ripening for 20days were changed into the favorable range for earthworm. The growth of earthworms in foodwaste and mixing waste of paper mill 30% was found to be 68%, 84% for the survival rate, 227%, 275% for the liveweight increasing rate, respectively. The ingestion rate of foodwaste and mixing waste of paper mill 30% indicate 0.72g/g·d, 0.81g/g·d, respectively. About 62∼75% of ingestion amount produce cast and characteristics of cast indicate pH 6.1∼6.5 organic component 34∼42%, salinity 0.35∼0.4, CEC 73∼94 me/100g, N, P, K concentration 0.8∼1.2%, 0.4∼1.6%, 0.43∼0.5% respectively. Therefore it can be evaluated that the casts are good soil condition and organic fertilizer.

• Environmental Analysis Health and Toxicology
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• v.6 no.3_4
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• pp.133-141
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• 1991

Vermistabilization is the stabilization of organic wastes using earthworms. The worms maintain aerobic conditions in the waste, accelerating and enhancing the biological decomposition of the waste. This study was carried out to find out fundamental factors affecting the performance of the process such as temperature, moisture content and pH condition of nightsoil sludge, and to evaluate the worms excreta (casting) as fertilizer. The results could be summarized as follows; the optimum range of temperature was observed 10~3$0^{\circ}C$ while survival rate of eathworm decreased rapidly at 35$^{\circ}C$ within 6 days and death occurred at 5$^{\circ}C$. Those of moisture content and pH condition were 50~70% and 5~8, respectively. Earthworms were revealed to change the composition of N in nightsoil sludge consisting of$NH_3$-N (71%), $NO_2$-N (2%) and $NO_3$-N (27%) into that $NH_3$-N (24%), $NO_2$-N (1%), $NO_3$-N (75%) in earthworm excreta, respectively The concentrations of NH$_3$and H$_2$S gas in pig manure were reduced by 59.2% and 45.2% in case of mixing pig manure with casting.

• Journal of Environmental Health Sciences
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• v.33 no.6
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• pp.488-492
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• 2007

The influence of additive materials including saw dust and cow manure in the ripening of leather sludge for the efficient vermisabilization was studied. The ripening characteristics of the leather sludge, the growth of earthworms in the growth bed and the by-products like cast were observed according to the mixing ratio of additive materials. When the mixed leather sludge of which the additive materials contents were over 20% were ripened for 50 days, the values of ORP and alkalinity were changed to the favorable ranges for earthworms, the positive (+) and below 1,000 mg/l as $CaCO_3$, respectively. The velocity of ripening improving the characteristics of the leather sludge was faster in the sludge mixed with cow manure than saw dust. This results could also be verified from the monitoring of the states of earthworm growth using the survival rate, the increase rate of lifeweight and the hatching rate of earthworm cocoon in the their growth bed packed with the ripened sludge. The values of CEC in cast, the vermi-stabilized sludge, were increased with the mixing ratio of additive materials, but the content of heavy metals was drcreased by the dilution effect and accumulation in the earthworm body. Above results show that the leather sludge might be efficiently stabilized by earthworms through the ripening for 50 days using additive materials. Cow manure can be used as a good additive materials for leather sludge as much as saw dust, and the optimum content of additive materials in the well-ripened leather sludge was about 30%.

• The Korean Journal of Soil Zoology
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• v.7 no.1_2
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• pp.17-21
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• 2002

Food waste which had been mixed with night soil sludge and composted for 21 days (mixing ratio = food waste/paper mill sludge : 1, w/w) was supplied to the 5 g of Eisenia fetida popualtion at various temperatures (5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 31, 32, 33, 34, 35$^{\circ}C$). The biomass of earthworms one month after feeding at 20-32$^{\circ}C$ was about two times more than that of the introduced earthworms, increasing rate of which was much higher than them at the other tested temperatures . There were decreases at temperatures below 7$^{\circ}C$, and less increases at temperatures of 8-10$^{\circ}C$ in biomass. Earthworms could not survive at temperatures at 34$^{\circ}C$ and 35$^{\circ}C$. Feeding rates of earthworms were much higher at 20-32$^{\circ}C$ than them at the other tested temperatures, and there were no differences among them at temperatures of 20-32$^{\circ}C$. But at 3 months after feeding, the biomass and feeding rate of earthworms decreased severely even at 20$^{\circ}C$ and 30$^{\circ}C$, which was supposed to be due to the long term effect of salts, especially sodium chloride (NaCl) in the food wastes.