Background: There are high numbers of human pathogenic microorganisms existing in municipal sewage sludge including bacteria, viruses, and protozoan parasites. Therefore, BIOSOLIDS could be considered as the environmental contaminants and a major carrier of disease causing diseases. As the etiological agents of acute gastroenteritis and hepatitis, enteroviruses are one of the most significant enteric pathogens affecting human health. The aim of this research was to detect the enteroviruses in the sludge of two wastewater treatment plants (WWTP) in Isfahan, Iran.Methods: In this study, 30 biosolid samples were taken from two WWTPs. After measuring the temperature, the samples were transported to the laboratory and analyzed for total solids (TS), volatile solids (VS) and enteroviruses according to the test methods of Standard Methods (part 9510F) and manual of Control of Pathogens and Vector Attraction in Sewage Sludge from Environmental Protection Agency (EPA) appendix F.Findings: Average temperature of the samples was about 23o C. The average number of enteroviruses was 4.5×106 and 7.7×105 plaque-forming unit (PFU) in 4 grams sludge for two WWTPs, respectively. The statistical analysis revealed a significant association between the enteroviruses and volatile solids. The number of enteroviruses was higher in summer in comparison to autumn.Conclusion: The results showed that all the biosolid samples could not meet the Class A pathogen requirements for enteroviruses and poses a potential health risk for people exposed to. Therefore, restrictions in land application of BIOSOLIDS are required in order to protect public health and the environment. Moreover, special biosolid treatment procedures must be used to reduce pathogens and to meet land-application standards.

Introduction: The Lusaka Water and Sewerage Company (LWSC) produces ~800–1, 000 kg of treated sewage sludge per day at its Manchinchi wastewater treatment plant (WWTP). The BIOSOLIDS are used for land application purposes although the contaminant and pathogen composition and quality of the BIOSOLIDS have been unknown until this study. Zambia does not have legal standards and guidelines for BIOSOLIDS management or application. The Manchinchi plant in Lusaka suffers from constant breakdowns such that the effectiveness of the plant to produce quality grade BIOSOLIDS for land application use is questionable. In peri-urban areas, the problem of poor sanitation is being addressed using different technologies including urine diversion ecosan toilets. The effectiveness of ecosan toilets to stabilize faecal sludge has not been assessed in Zambia. The purpose of this study was to stabilize and characterize the BIOSOLIDS from Manchinchi plant and ecosan toilets. Stabilization was done by use of drying beds and irradiation. The parametres that were used for characterization were microbiological, parasitological and heavy metals.Results: BIOSOLIDS from the Manchinchi WWTP sun drying bed, ecosan toilets and from an experimental plasticcovered drying bed were found to contain different pathogenic microorganisms and contaminant levels. A radiation dose and time-related declining trend in pathogens loads in BIOSOLIDS were observed. By the third week, no viable Ascaris eggs were detected. Based on controlled conditions, the BIOSOLIDS quality was found to be within the internationally acceptable standards for restricted use.Conclusions: Both the untreated LWSC BIOSOLIDS and ecosan sludge contained pathogen levels with the potential to cause environmental and public health hazards if used for agriculture purposes. Under plastic-covered drying beds, viable Ascaris eggs were not detected by the fourth week of treatment and the BIOSOLIDS were stabilized to levels equivalent to Class C of the Australian standards for restricted land application. Covered drying beds can be considered as cost effective stabilization treatment technology for BIOSOLIDS in developing countries. The technology has potential benefits for improving public health and reducing environmental pollution in Zambia, especially during the rainy season when BIOSOLIDS are directly discharged into the environment.

Lack of well-stabilized BIOSOLIDS is a basic problem for many municipal wastewater treatment plants in Iran. Disposed BIOSOLIDS from west Ahvaz wastewater treatment plant were generally used for agricultural activities. Initial evidence showed that these BIOSOLIDS were untreated and had the potential to transmit many pollutants to the environment and create hazards for public health, although anaerobic digester was selected for this wastewater treatment plant. The main objective of this research was to evaluate and optimize the bacteriological quality of BIOSOLIDS by lime addition in west Ahvaz wastewater treatment plant. The stability and reuse potential of BIOSOLIDS from existing anaerobic digester and lime added BIOSOLIDS were investigated. Lime addition to BIOSOLIDS was performed in the reactor with 30 L capacity. Averge amounts of fecal coliforms and viable helminthes ova in disposal BIOSOLIDS from anaerobic digester were 1.3×1015 MPN / g of dry solids and 314 ova / 4 g of dry solids, respectively. By lime addition with the ratio about 0.265 g Ca (OH)2 per g of dry solids, pH was not dropped under 12 and growth of fecal coliform was not detected after 30 days. In this regard, discharged BIOSOLIDS from this plant was unstable and very dangerous for reuse or disposal. Lime addition could stabilize the BIOSOLIDS and reduce fecal coliforms more than 99.99% and had concordance with class B of United State Environmental Protection Agency criteria. Lime-stabilized BIOSOLIDS could hence be well used for reconditioning the poor soil and for covering of solid waste landfill-sites.

The objective of this research is to investigate the effect of four additives including iron slag (IS), works debris (WD), fly ash (FA), and lime kiln dust (LKD) on the biochemical properties of bio solids produced at Mangere Wastewater Treatment Plant (MWWTP), Auckland, New Zealand. All these additives are homogenously mixed in the laboratory with bio solids at various percentages with and without lime. All these prepared amendments are compacted into polyvinyl chloride (PVC) tubes for curing durations of 2 weeks, 4 weeks and 8 weeks. Water content (WC), volatile solids (VS), pH, total organic carbon (TOC) concentrations, proteins, carbohydrates, lipids and VFA’s (volatile fatty acids) are determined for all the samples. These parameters are analyzed initially and after 2, 4 and 8 weeks for every PVC tube. Results indicated that when biochemical changes occurred within bio solids, all of these parameters results are affected. After comparing results of all the amendments it is concluded that FA 50% with lime 20% inhibited most of the biological activities and maintained pH of bio solids at elevated level of 12 or above for 8 weeks and thus can be applied to bio solids for stabilization before land filling. FA 50% with lime 20%, like all the other additives, is added to wet bio solids on the basis of dry weight. Solid content of bio solids is around 25% so the addition of even 70% additive to wet bio solids on the basis of dry weight is very less in amount.

BIOSOLIDS must be stabilized in order to reduce odors, which have been noted as a major concern with respect to alkaline stabilization. Stabilization is designed to address potential putrefaction processes, odiferous releases and vector attraction concerns. Also, most alkaline processes are open systems in which temperature and mixing are more difficult to control, and factors such as increased pressure or bactericidal action of un-ionized ammonia are not present to aid in disinfection. The purpose of this project was to begin assessment of the long-term stability of an advanced alkaline product resulting from operating conditions established by testing previously conducted and approved by EPA's Pathogen Equivalency Committee. The conditions formerly established as optimum to achieve required pathogen destruction resulted in the ability of advanced alkaline system to operate at a lower temperature of 55oC as opposed to the temperature of 70oC required by the U.S. EPA 40CFR Part 503 Final Rule Standards for the Use or Disposal of Sewage Sludge. All previous data collected regarding the ability of the advanced alkaline product to remain stabilized over long periods of time were related to the material produced at the higher temperatures which indicated no significant decline in pH over a time of 5 years. The goal of this research is to obtain better understanding of the stabilization of BIOSOLIDS over time, lower costs, reduce odor formation and to reduce vector and pathogen attraction so to comply with the current requirements.

The composting process is a useful method of producing a stabilized material that can be used as a source of nutrients and soil conditioner. Maturity of compost is essential for its optimal use as a soil amendment and a source of plant nutrients as well. Immature composts pose problems of malodors and flies and phytotoxicity and pollution during use. Stability and maturity both are required for compost quality control. Compost maturity tests can be classified into physical, chemical, plant, and microbial activity assays. In this study, several methods of evaluating the stability and maturity of composted BIOSOLIDS were compared based on chemical and biological properties. The sludge used of windrow composting was obtained from the drying beds of South Isfahan wastewater treatment plant. The results showed that, C/N ratio after 100 days of composting reached to 15/1; NH4/NO3 ratio decreased with increase of the time dewatered sludge compost, which this loss is 57.3%. The content of volatile solids, 28.8% decreased with composting time. The number of fecal coliforms in the initial sewage sludge compost was 17.9¢106 and at the end of composting was 898MPN/g of total solids and the compost process provided class A pathogen criteria. Use of chemical and biological parameters exhibited three phases: rapid decomposition (day 40), stabilization (day 80) and maturation (day 100) in BIOSOLIDS compost. Thus, the biosolid compost was mature and ready for use as an agricultural substrate after about 100 days of composting.