Showing 5 results for Sewage Sludge
M Farzadkia, H Taher Khani,
Volume 15, Issue 47 (6-2005)
Abstract
Background and purpose : Currently, there is only one sewage treatment plant in Sercan City in Hamadan province. Extended aeration activated sludge is the main process of the plant and untreated effluent and disposal sludge are used for agricultural activities. The main objective of this research is to evaluate the stabilization degree and reuse potential of disposal sludge from the plant.
Materials and methods : This study was undertaken over a 12 months period from March 2001 to March 2002. In this project some indexes of sludge stabilization and reuse including VS/TS ratio, pH, SOUR, floatation, color, odor, coliform and fecal coliform were determined.
Results : The annual average ratio of VS/TS and SOUR in disposal sludge from this plant were 0.73 and 3.37 mg02/gr.vs.h, respectively. The average pH was about 7. The disposal sludge was septic and had dark brown color and floated after a short time. Also the annual average of fecal coliform density in disposal sludge was 8.97 ´ 107 MPN/g.ds.
Conclusion : The disposal sludge was raw and destabilized. The microbial quality of disposal sludge was lower than the class B of USEPA regulation. Therefore, this sludge can not be discharged to environment or reused.
Mohammad Malakootian, Mohammad Mobini, Golam Abbas Nekoonam,
Volume 24, Issue 116 (9-2014)
Abstract
Background and purpose: Direct application of sewage sludge in agriculture is limited due to the presence of pathogens, improper fermentation of organic waste and heavy metals in the sludge. Co-composting of sewage sludge and other waste is a method for safe and healthy disposal to reuse sewage sludge. This study investigated the possibility of producing compost from sewage sludge and pistachio hull waste.
Material and Methods: A cross-sectional study was conducted in the winter of 2014 at the Environmental Health Engineering Research Center affiliated to Kerman University of Medical Sciences. First, a cylindrical reactor was made which was 30liters in volume, 30cmdiameter in dimensions, 45cm depth, and wall thickness of 6 mm. Pistachio hull waste with sewage sludge was mixed in a ratio of 1 to 4 and C/N ratio of 25. Reactor started with aeration rate of 5 liters per minute. The reactor content was mixed every five days, and the resulting compost samples were measured for moisture content, pH, electrical conductivity, organic carbon, total nitrogen, phosphorus, potassium, cadmium, and lead.
Results: After 30 days from the start of composting process, the carbon to nitrogen ratio decreased to 16.5. During the composting process, pH increased but the amounts of electrical conductivity, total nitrogen, organic carbon, phosphorus, potassium, lead, and cadmium decreased. The maximum temperature reached 63ºc.
Conclusion: The properties of the produced compost including temperature, pH, electrical conductivity, moisture ratio, C/N,P, K, and heavy metals were in category 1 and 2 of the standard compost of Iran.
Mohammad Ali Zazouli, Hosseinali Asgharnia, Jamshid Yazdani Cherati , Hajar Ziaee Hezarjeribi, Abbas Ahmadnezhad,
Volume 25, Issue 124 (5-2015)
Abstract
Background and purpose: Sewage sludge can contain heavy metals. This study aimed at investigating the effect of cow manure as bulking agent on concentration of heavy metals (cadmium, chromium, copper and lead) during municipal sewage sludge vermicomposting and compares that with standard levels.
Materials and methods: In an experimental research, vermicompost was produced by mixing sewage sludge and cow manure using earthworms (Eisenia Foetida species). Composting process was conducted in 27 pilots for three months. The heavy metals concentrations were measured by atomic absorption spectroscopy in the vermicomposting process. Then, data was analyzed by descriptive statistics and statistical test of Repeated Measured ANOVA.
Results: In all pilots the heavy metals concentration decreased with increasing vermicomposting time. Reduction in Cd, Cr, Cu and Pb concentration values in the vermicompost produced from mixture of sewage sludge and cow manure was found 50% higher than other pilots. The concentration of heavy metals of in terms of kind of composted material decreased significantly in all pilots (P<0.05). Concentration of heavy metals for the number of worms also decreased in all pilots but this decrease was not found to be significant (P>0.05). Therefore, a compost produced by a mixture of 50% sewage sludge, 50% cow manure and 40 Eisenia Foetida in 1.2 Kg could have a higher quality in terms of heavy metals.
Conclusion: The concentration of heavy metals was lower than the standard levels set by Iranian national (class I and II), WHO and US Environmental Protection Agency. The use of cow dung as a cheap and available bulking agent is recommended in vermicomposting of sewage sludge.
Elham Hosseini Panah, Afshin Takdastan,
Volume 25, Issue 133 (2-2016)
Abstract
Background and purpose: Toxicity, high levels and complex nature of petroleum hydrocarbons in drill cutting can endanger human health since many of these compounds are among carcinogenic hazardous waste components. This study aimed at comparing the effect of compost and vermincompost processes in removing petroleum hydrocarbons from drill cutting located in Ahvaz oil field with sewage sludge.
Materials and methods: An experimental study was performed in which the effect of a 1:1 mixture of biological sludge with drill cutting contaminated with TPH, along with sawdust and horticultural waste was examined for composting and vermicomposting. The degradation time was about 60 days in pilot chamber. The TPH, carbon to nitrogen ratio, pH, EC, volatile solids, and temperature levels were measured. To ensure the integrity and accuracy of measurements testing was done in 3 iterations.
Results: The mean TPH level in the drill cutting in Ahvaz oil field was 42.004 g/kg that reduced to 11.31 and 18.77 g/kg during two months treatment by vermicomposting and composting with biological sludge, respectively. The removal efficiency of TPH in drill cutting in vermicompost pilot was 73.06% while it was 55.30%. in compost pilot.
Conclusion: In this study, vermicompost process to be highly capable of removing TPH from oil-based drill cutting.
Mahtab Momeni, Mahdi Farzadkia, Ali Esrafili, Majid Kermani,
Volume 27, Issue 158 (3-2018)
Abstract
Background and purpose: There are several methods for removing oil contaminations from the polluted environments. Bioremediation could be considered as one of the best and most practical methods in the removal of oil contaminations. The aim of this research was to determine the bioremediation efficiency for soils contaminated with diesel by the biological stimulation of bioreactors containing vermicompost and activated sludge.
Materials and methods: In an experimental study, the soil samples were collected from an area which was free of any oil pollution and 5 reactors containing one kilogram of soil were contaminated with diesel at the mass concentration of 1%. Two reactors were mixed with vermicompost at 15% and 20% mass concentrations and two reactors were mixed with activated sludge at 5% and 10% mass concentrations. Additionally, one control reactor was used to control the process. The pH of the reactors was between 7.5 and 8 and the C:N:P ratio was 100:5:1. The amount of TPH was measured at seven retention times within three months with two repetitions. The total removal of petroleum hydrocarbons (TPHs) was evaluated by GC-FID device.
Results: The highest removal efficiency of TPH (40.24%) was observed in bioreactors containing vermicompost at a 20% mass concentration. In this reactor, the highest percentage of removal was observed in lighter hydrocarbons (50.49%). In reactors containing activated sludge, the average percentage of TPH removal was 32% which was observed in the reactor containing the 10% concentration of sludge. In this reactor, the highest percentage of removal (44.86%) was also observed in lighter hydrocarbons.
Conclusion: Vermicompost and activated sludge can be used in the bioremediation of soils contaminated with diesel. In current study, the performance of vermicompost was found to be more efficient. Also, the results showed that by increasing the concentration of biological modifiers, the removal rate would increase.