Background: Sewage SLUDGE (Biosolids) is a byproduct of WASTEwater treatment that accumulates in large quantities. Effective stabilization and disinfection of sewage SLUDGE prior to land application are necessary to not only protect human health, but also to induce the public its benefits and safety. Currently, many WASTEwater treatment plants in Iran dispose great amounts of untreated sewage SLUDGE to the environment. Objectives: The purpose of this work was to upgrade WASTEwater treatment plants by lime stabilization of WASTE SLUDGE. Materials and Methods: Lime stabilization of WASTE SLUDGE from Shoosh WASTEwater treatment plant was performed in a 10-L reactor.Microbial quality of lime-stabilized SLUDGE was checked for 6 weeks in the reactor. During this stage, pH, FC (fecal coliforms) and viable helminthes ova density were determined and compared with SLUDGE stabilized criteria suggested by USEPA.Results: Average number of fecal coliforms and viable helminthes ova in WASTE SLUDGE were 1.65 × 1012 MPN/g of dry solids (DS) and 353 ova/4 g of dry solids, respectively. Conclusions: The results of this study showed that sewage SLUDGE stabilization with hydrated lime reduced fecal coliforms more than 99.99% and also stabilized SLUDGE covered standards of class B of USEPA criteria.

Biological removal of lead was observed in this study during treatment of synthetic solutions of this heavy metal by a sample of WASTE ACTIVATED SLUDGE (WAS) having MLSS concentration of 10000 mg/L. The objective was determining the capability of WAS in removal of lead in three different conditions of treatment: without any aeration and feeding, by simultaneous aeration and feeding and by aeration without feeding. Besides, the effect of initial metal concentration and contact time in these treatment stages were determined.Results showed that the efficiency of lead removal was reduced by increasing the initial metal concentration, but the changes of contact time had resulted in different responses depending to the test condition. Moreover, it was found that the effects of aeration and feeding in increasing the efficiency of treatment were more pronounced for the stage of treating lower concentrations of lead. The maximum removal of lead in the first step (without aeration and feeding) was 55.2 % in contact time of 75 minutes, in the second step (without feeding and by 12 hours aeration) 63.3% and third step it was 94.2 % in contact time of 48 hours .The initial lead concentration in these experiments was 5 mg/L.

ACTIVATED SLUDGE process is commonly utilized for the treatment of WASTEwater with the benefits of high efficiency and easy operation. However, during the biological treatment of WASTEwater, huge amounts of WASTE biomass (called as “ WASTE ACTIVATED SLUDGE (WAS)” ) are inevitably generated in the process. The WAS should be treated in order to reduce the water content of raw WAS, transform the highly putrescible organic matter into stable or inert organic and inorganic residue, and finally condition the residue to meet disposal acceptance regulations. But, WAS treatment and disposal, representing 50– 60% of the total operating costs of the WASTEwater treatment. WAS is produced in massive volumes; specifically, more than 25, 000 tons of WAS is produced in Iran per year. Anaerobic digestion is one the most applicable methods in WAS stabilization due to its ability to reduce WAS volume and produce biogases. A mixture of primary and secondary SLUDGE (WAS) passes through anaerobic digestion, but this process is more difficult for WAS than primary SLUDGE. However, the hydrolysis stage limits anaerobic WAS digestion. To optimize the general process of WAS anaerobic digestion and increase hydrolysis performance, it would be possible to pre-treat WAS by various mechanical, thermal, chemical, and biological methods. In this research the influence of ultrasonic bath pre-treatment was studied to observe the effects of ultrasonic density and sonication time on WAS solubilisation. The charactristics of ultrasonic wave producer was surface area of 240×137 mm2, frequency of 40 kHz, power of 265W. Increases in soluble chemical oxygen demand and soluble polysaccharide concentration, as well as the decrease in volatile suspended solids, indicate that pre-treatment could cause WAS solubilisation. The cavitation produced by ultrasound waves radiation breaked down the bacterial cell wall and released the intracellular substances into an aqueous phase. Since polysaccharide is one of the main parts of extracellular polymeric substances (EPS), a polysaccharide concentration increase in the solution indicated that ultrasonication disintegrates WAS floc and the EPS value reduced in biological flocculation. Increases in ultrasonic density and sonication time caused more solubilisation, stronger cavitation arised with an increase in ultrasonic density and with increased ultrasonic density; more floc structure disintegration was achieved in less time. The best Pre-treatment efficiency was achieved in ultrasonic density 0. 53 W/mL and 20 min. sonication time and it caused 20% increase in biogas production and 24% volatile suspended solids solubilisation compared to the control sample. The volatile solids after anaerobic digestion of pre-treated SLUDGE also decreased. Increament in ultrasonic density and snication time had direct relation with volatile solids reduction. The best volatile solids efficiency was achieved in ultrasonic density 0. 53 W/mL and 20 min. sonication time and it caused 48% decrease in volatile solids Given the change in WAS, electrical conductivity with ultrasonic bath pre-treatment, in addition to other tests like chemical oxygen demand and volatile suspended solids, electrical conductivity could also effectively assess WAS solubilisation.

Mathematical modeling allows a large number of potential aerobic digestion process designs to be evaluated and the performance of aerobic digesters to be predicted. In applying such models, however, it is essential to use appropriate models that can neatly explain the kinetics of the process. In this research, the simple first-order model (known as Adams model) and ACTIVATED SLUDGE models developed by International Water Association (ASM1 and ASM3) were evaluated. For this purpose, three batch reactors with initial TSS concentrations of 5, 000, 10, 000, and 20, 000 mg/L and operating volumes of 10 L were operated to collect the experimental data required for model calibrations. Batch reactors were run and monitored for 70 days. Samples taken from the reactors were analyzed for their solids concentrations and their Chemical Oxygen Demand (COD). The measured data were then used to estimate the parameters of the models investigated and the best sets of parameters yielding the best fit of the predicted and measured data were identified for each model and for each reactor. The parameter estimation results for batch runs showed that higher SLUDGE concentrations were associated with lower cell decay coefficient values. The error values for batch runs calculated by ASM3 were found to be lower than those calculated by Adams model and by ASM1. Comparisons with experimental data proved ASM3 to be superior in terms of its capability to predict concentrations in aerobic digestion batch reactors.

Biological treatment of industrial WASTE water with ACTIVATED SLUDGE is Knon as one of the most effective methodes in removing toxic material such as formaldehyde. In this research it is attempted to set in motion and preserved the biological formaldehyde treatment system with ACTIVATED SLUDGE and the existing microorganisems will use the formaldehy as their food to grow.That is why an aerobic reactor with the volume of 8 liter known as Bioreactor is used. The primary biologic environment is provided by the returned SLUDGE in Zargandeh WASTE Water treatment plant and the system is started in the form of Batch.The input optimum formaldehyde as well as desired retention time to obtain the most efficient way for COD elimination and output formaldehyde are provided the highest percentage of COD volume with input formaldehyde concentration 70.ppm would be when retention time is 24 hours. Input formaldehyde concentration increase or residence time decrease will result in reduction of COD and pH elimination percentage.

Background and Objectives: A conventional treatment to stabilize the excess ACTIVATED SLUDGE is the aerobic digestion process but due to longaeration time, it requires large equipments as well as high investment cost. Because of high oxidation potential of ozone, SLUDGE ozonation enhances stabilization rate and reduces SLUDGE treatment equipment size and cost. Therefore, in this study, the combination of pretreatment with ozone and aerobic digestion processes were investigated.Materials and Methods: The experimental set-up consisted of an ozonegenerator and ozonation reactor with the total volume of 2 L. Removal percentages of TSS, VS, total and soluble COD, HPC, fecal coliform and settable solids were measured in integrated process compared to the single ones.Results: The results of this research indicated that the aerobic digestion of WASTE ACTIVATED SLUDGE during 10 days could reduce 38% of volatile solids and thus obtaining the EPA standard. Also, the results of combined ozonation and aerobic digestion revealed that the pre - ozonation at 0.25 g O3/g TS or 0.5 g O3/g TS with 6 or 3 days aeration, respectively, could achieve 38% reduction in VS and hence the requirement set by EPA. Therefore, integration of pre-ozonation with aerobic digestion can significantly reduce the digestion time to attain the standards.Conclusion: The SLUDGE pre-ozonation with low dose of ozone due to solids disintegration can enhance the efficiency of aerobic digestion in WASTE ACTIVATED SLUDGE stabilization, and consequently decrease size of equipments, air requirement, investment and probably operation cost.

The ACTIVATED SLUDGE process simply involves bringing together WASTEwater and a mixed culture of microorganisms under aerobic conditions. The system usually includes a secondary treatment given to the settled sewage, and requires an environment in which active microorganisms are maintained in intimate contact with WASTEwater in the presence of sufficient oxygen. In this study, the treatment of industrial effluents, by using laboratory ACTIVATED SLUDGE unit was investigated. The reduction of the pollution laws was determined, using the biochemical oxygen demand (BOD) and the chemical oxygen demand (COD) methods. The results indicated that the pollution laws were reduced by up to 98% in the ACTIVATED SLUDGE unit.