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Co-composting of Dewatered Sewage Sludge with Sawdust  [PDF]
EdrissBazrafshan,Mohammad ali Zazouli,Javad Bazrafshan,Anoushirvan Mohseni Bandpei
Pakistan Journal of Biological Sciences , 2006,
Abstract: The objective of this study is determining the optimum conditions of co- composting of dewatered sewage sludge and sawdust. To perform this study, the dewatered sewage sludge with humidity between 78-82% was mixed with sawdust. Turning over did once a week for aeration. Temperature was monitored at different depths daily. Other parameters such as N, C, organic matters, pH, heavy metals, total and fecal coliform and Salmonella were determined three times a week. The results of this study showed that after about 15th days, temperature of the mixture reached up to 55°C and was stabled for 15 days. Percent of dry solids increased from about 37.87 to 66.58%. At present study, a C:N ratio of 26.63:1 is considered and at the end of composting period reached about 20.52:1. Microbial parameters such as total and fecal Coliforms and Salmonella decreased significantly at the end of composting period so, the number of total and fecal Coliforms and also Salmonella decreased to A class standards of US EPA at the end of the operation. The computed correlation coefficients and the p values show a significant correlation between reduction of organic content and microbial parameters (R2 = 0.91, p<0.001). Also, organic matter and organic carbon of the mixture decreased during of the study, due to increasing the temperature. The result indicated that co-composting of sewage sludge with sawdust is a reliable and simple method to schedule, with high flexibility and low odor production. Organic compounds and pathogenic microorganisms reduced and EPA standards were met during this method.
Soil microbial attributes treated with composting of sewage sludge  [cached]
Ericléia Büerg Suszek,Paulo Fortes Neto,Nara Lúcia Perondi Fortes,Eliana Maria de Araújo Mariano da Silva
Ambiente e água : An Interdisciplinary Journal of Applied Science , 2012,
Abstract: The use of sludge composting in agricultural areas alters the microbial functions. In this context it is necessary to evaluate the impact of composting addition on microbial activities in the soil. This study evaluated the alteration of microbial attributes of a soil fertilized with sewage sludge compost by measuring the CO2 release rates and counting bacteria and fungi numbers. This experiment was conducted in laboratory using respirometric jars that contained samples of soil mixed with different doses of compost: 0; 20; 40; 60 and 80 Mg ha-1, and CO2 release was quantified daily during the 28 days of incubation when the samples were removed from the jars and bacteria and fungi quantities were counted. The treatments corresponding to each dose of the composting were arranged in completely randomized design with four replications. The CO2 release and the quantity of bacteria and fungi increased with additional doses of the compound. This occurred as a result of supplying energetic substrate and nutrients from the compound. The CO2 released measurements indicated that compound above 20 Mg ha-1 has significant impact on soil microbial activity.
Changes of Cu, Zn, and Cd speciation in sewage sludge during composting
GAO Ding,ZHENG Guo-di,CHEN Tong-bin,LUO Wei,GAO Wei,ZHANG Yi-an,LI Yan-xia,
GAO Ding
,ZHENG Guo-di,CHEN Tong-bin,LUO Wei,GAO Wei,ZHANG Yi-an,LI Yan-xia

环境科学学报(英文版) , 2005,
Abstract: The potential toxicity risks from heavy metals depend on their chemical speciation. The four stages of the Tessier sequential extraction method were employed to investigate changes in heavy metal speciation(Cu, Zn, and Cd) of sewage sludge during forced aeration composting, and then to identify whether the composting process would reduce or enhance their toxicities. Throughout the composting process, the exchangeable, carbonate-bound, Fe-Mn oxide-bound, and organic matter-bound fractions of Cu were converted to the residual Cu fraction. The organic matter-bound Cu fraction greatly contributed to this transformation. Residual Zn fraction was transformed to the Fe-Mn oxide-bound and organic matter-bound fractions after composting. The residual Zn fraction was a major contributor to the organic matter-bound Zn fraction. The availability of Cu and Zn was reduced by composting such that the risk of heavy metal toxicity decreased with prolonged treatment times. Additionally, attention should be paid to the increased availability of Cd in sewage sludge after composting treatment.
Composting MSW and sewage sludge with effective complex microorganisms
XI Bei-dou,LIU Hong-liang,ZENG Guang-ming,HUANG Guo-he,BAI Qing-zhong,
XI Bei-dou
,LIU Hong-liang,ZENG Guang-ming,HUANG Guo-he,BAI Qing-zhong

环境科学学报(英文版) , 2002,
Abstract: The effects of complex microorganisms in composting process of the municipal solid waste (MSW) and sludge were examined through inspecting biomass, temperature, oxygen consumption, organic mater, and C/N (the ratio of carbon and nitrogen). The experimental results shows: complex microorganisms are effective to compose organic matter and speedup composting change into humus.
Ambient air temperature Effects on the temperature of sewage sludge composting process
Ambient air temperature effects on the temperature of sewage sludge composting process

HUANG Qi-fei,CHEN Tong-bin,GAO Ding,HUANG Ze-chun,
HUANG Qi-fei
,CHEN Tong-bin,GAO Ding,HUANG Ze-chun

环境科学学报(英文版) , 2005,
Abstract: Using data obtained with a full-scale sewage sludge composting facility, this paper studied the effects of ambient air temperature on the composting temperature with varying volume ratios of sewage sludge and recycled compost to bulking agent. Two volume ratios were examined experimentally, 1: 0: 1 and 3: 1: 2. The results show that composting temperature was influenced by ambient air temperature and the influence was more significant when composting was in the temperature rising process: composting temperature changed 2.4-6.5 degrees C when ambient air temperature changed 13 degrees C. On the other hand, the influence was not significant when composting was in the high-temperature and/or temperature falling process: composting temperature changed 0.75-1.3 degrees C when ambient air temperature changed 8-15 degrees C. Hysteresis effect was observed in composting temperature's responses to ambient air temperature. When the ventilation capability of pile was excellent (at a volume ratio of 1:0:1), the hysteresis time was short and ranging 1.1-1.2 h. On the contrary, when the proportion of added bulking agent was low, therefore less porosity in the substrate (at a volume ratio of 3:1:2), the hysteresis time was long and ranging 1.9-3.1 h.
Sewage sludge composting simulation as carbon/nitrogen concentration change

Kabbashi Nassereldeen,

环境科学学报(英文版) , 2011,
Abstract: Available composting models do not describe accurately the dynamics of composting processes. Difficulty in modeling composting processes is attributed mainly to the unpredicted change in process rate caused by change in activation energy value (E). This article presented the results of an attempt made to utilize patterns of change in carbon, nitrogen and temperature profiles to model sewage sludge composting process as a multi-stage process. Results of controlled sewage sludge composting experiments were used in the study. All the experiments were carried out as batch experiments in a 300-liter Horizontal Drum Bioreactor (HDB). Analysis of the profiles of carbon, nitrogen and temperature has indicated that there were clear patterns that could be used to develop simple models of the process, the initial C/N ratio was between 7-8 and the final C/N ratio of the compost in most experiments were found to be around 15.0, indicating the compost was fully matured and could be used safely for agricultural purpose. Electrical conductivity of composting material decreased from 1.83 to 1.67 dS/m, after a period, it increased gradually from 2.01 to 2.23 dS/m and remained at around 2.33 dS/m till the end of composting. It is found that change in the concentration of total carbon can reasonably be described by three constant process rate coefficients (k1, k2, k3). It is found that the process starts with a certain process rate coefficient (k1) and continues until peak temperature is reached, then it reaches lower process (k2) in the declining phase of the thermophilic stage, and finally it proceeds with a faster process rate (k3) when maturation is reached. Change in the concentration of total nitrogen has shown to have the same patterns of change as carbon.
Effect on Sewage Sludge Composting with Different Aeration Modes

Yuansong Wei,Chengqiang Li,Yaobo Fan,Minjian Wang,Zhiping Jia,

环境科学 , 2001,
Abstract: Two kinds of aeration modes, five kinds of amendment were tested in sewage sludge composting. The pile temperature rose to the set temperature(60 degrees C) and could maintain some thermophilic period. The pathogen reduction of sewage sludge compost met with the control standard. Compared with positive forced aeration, the natural aeration combined with positive forced aeration made the pile temperature rise faster and consume less energy. However, the positive forced aeration could accelerate the moisture content reduction and the organic matter degradation of mixtures of sewage sludge and amendment. The moisture content of raw materials affected the composting process very much, and should be less than 80%. The pH value of raw materials need to be adjusted during the sewage sludge composting process.
A review of moisture measurements in the process of sewage sludge composting

CAI Lu,CHEN Tongbin,LIU Hongtao,GAO Ding,ZHENG Guodi,

环境科学学报 , 2012,
Abstract: Rapid and accurate moisture measurements are crucial and beneficial to the management of composting process and the optimization of technology. This review summarizes and examines the moisture measurements of compost material during the process of sewage sludge composting. Moisture measurements that could be utilized in composting are introduced and compared. It suggests that instruments for moisture measurements should be modified because of the intricate composting condition. As far as engineering application is concerned, an in-situ moisture measurement based on dielectric method is recommended to guide the composting management and to optimize the technology to improve the composting efficiency.
Journal of Research in Medical Sciences , 2002,
Abstract: Introduction. Sludge production from municipal wastewater treatment plants should have quality standards before disposal in to the environment. Environmental specialists classified sewage sludge as a hazardous waste because of high organic compounds and pathogenic microorganisms. They belive that sewage should be stabilized before disposal and so composting of sewage sludge is an effective and economical method to stabilize. Sewage sludge compost could be used to improve soil structure and enrich the soil with nutrients. Methods. To evaluate the optimum conditions of aerobic compost, the mixture of dewatered sewage sludge from Isfahan municipal waste water treatment plant and sawdust as bulking agent were used. Pilot scale study were performed in Isfahan municipal waste water treatment plant. To perform this research project, the dewatered sewage sludge with humidity between 78 to 82 percent were mixed with sawdust. Turning over method of the piles with one week interval were applied to aerate the mixture. Temperature of the piles were monitored at different depths daily. Other parameters such as N, G, organic matters and pH were determined weekly. Total and fecal coli form, and salmonella were determined at the beginning and end of the composting process, also heavy metals were measured at the same time. Results. The results of this study showed that after days, temperature of the mixture reached up to 55 G, and were stabled for 15 days. Humidity, organic matter, organic carbon and GIN ratio of the mixture decreased over the period of the study, due to increasing the temperature. Also organic matter and humidity mainly decreased in thermofilic phase. The number of total and fecal coliform and also salmonella decreased to A class standards of US.EPA at the end of the operation. Discussion. The results of the study also showed that, this type of composting method is reliable, and simple to schedule, with high flexibility and low odor production. Organic compounds and pathogenic microorganisms reduced and EPA standards were reached during this project.
Application of complex microbial inoculants in the high-temperature and aeration composting sewage sludge

XU Xiao-Ying,LI Ji,
,李 季

中国生态农业学报 , 2006,
Abstract: The application of complex microbial inoculants in the high-temperature and aeration composting sewage sludge was studied.The results show that the efficiencies of the complex microbial inoculants are not significiant for the reduction of the time for reaching the high-temperature period,the increase of the numbers of bacteria,fungi and actinomyces in a composting process of sewage sludge.But the sustained time of high-temperature is longer by inoculating the complex microbials,and the decomposition can be reached 3 days ahead of time.
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