[Evaluation of phosphorus removal from filtered effluent of activated sludge using the electrochemical process]

Phosphorus [in a concentration range of 0.005-0.05 mg/L-P] is enough for eutrophication of water bodies; therefore, phosphorus removal from effluents is necessary. The electrochemical process is one of the methods used for phosphorus removal. Thus, this study aimed to examine the effect of the electrochemical process on phosphorus removal from filtered effluent of activated sludge. This bench-scale experimental study was carried out on the samples of filtered effluent of activated sludge in a batch system. Phosphorus concentrations for 210 samples were measured through stannous-chloride method [The Standard Method, 4500 P-D.]. Data were analyzed using Green house Geisser, one-way ANOVA and the Tukey's post- hoc tests. The average phosphorus concentration before the electrochemical process in the filtered samples and the maximum efficiency of phosphorus removal were 1.93 +/- 0.86 mg/L-P and 98%, respectively. The residual phosphorus concentrations [electrical current >/= 0.3A, reaction time >/= 10min] in all samples were decreased to less than 1mg/L-P. Results showed that the electrochemical process can decrease the residual phosphorus to less than the standard limit [1mg/L-P] in Iran. The plot for the average residual phosphorus concentrations versus reaction time is a straight line [R[2]=0.837]. Phosphorus removal from the samples of filtered effluent of activated sludge is considered as a second-order reaction and the fitted model can be formulated as y= -0.001x[2] + 0.133x + 0.875 [R[2]=0.925]

[Comparing the effect of electrochemical process and Alum coagulation in removing turbidity and coliform bacteria from the synthetic wastewater]

Nowadays, 1.1 billion people in the world do not have access to a safe and adequate water supply. So, seeking more efficient water treatment methods are a critical need. This study designed to compare the effects of the electrochemical process [EP] and Alum coagulation on turbidity and coliform bacteria removal from the synthetic wastewater [SW]. This experimental study was conducted on five SW samples in a batch system. First, the optimum Alum dosage and pH were determined by Jar-test. Thereafter, samples were subjected to coagulation and 10 samples were taken before and after the process. The EP was accomplished on each five SW samples. In each run, a 600 mA DC was applied on 1700 ml of SW using aluminum electrodes for 1 hour and one sample was taken every 10 minutes [35 samples]. The turbidity and most probably numbers of total coliforms were confirmed and the fecal coliforms as well as the heterotrophic plate count [HPC] were determined for all samples according to the standard methods book instructions [21st edition]. The optimum Alum dosage and pH range for coagulation were 16mg/L and 7 pH units, respectively. Using coagulation, the removal efficiencies for the total, confirmed and fecal coliforms were 80.57%, 48.89%, and 65.59%, respectively. Moreover, the removal efficiencies for HPC and turbidity were 89.92% and 91.11%, respectively. The EP not only removed 100% of the coliforms, but also reduced both HPC and turbidity to 91.05% and 96.31%, respectively. The EP is more effective than Alum coagulation in the removal of turbidity and bacteriological indicators from the synthetic wastewater

[Coliform bacteria removal from contaminated water using nanosilver]

Although silver can be used as an effective water disinfectant, it has some disadvantages such as its high costs and darkening of the skin and mucous membrane due to long-term exposure to high silver concentrations. Nanotechnology can solve such problems through reduction of silver content. The aim of this study was to evaluate the effect of nanosilver on removing the coliform bacteria from contaminated water. This bench-scale experimental study was carried out in a batch system on artificially contaminated water samples prepared by adding 5 ml effluent to 60 liters of tap water. In each run, the nanosilver suspension [30-180 microgL-1] was added to 6 containers [500 ml] of contaminated water and then a sample was taken every 20 minutes for a 100-minute period and tested for coliform according to the standard methods book. Results revealed that the coliform bacteria removal significantly increased with increasing the contact time of nonosilver [P=0.001], but there was no significant correlation between the nanosilver concentrations and coliform removal [P=0.6]. The maximum coliform removal [92.41%] was achieved within 100 minutes contact time for 60 microgL-1 of silver. Although nanosilver treatment is effective in removing coliform from contaminated water, further researches are required to study the efficacy of drinking water disinfection

[Electrochemical process efficiency for the removal of organic phosphorus from synthetic wastewater]

Phosphorus compounds are among the potential water pollutants which enter the water resources through different ways such as wastewater discharge. Although there are physical, chemical and biological treatment methods for phosphorus removal from the wastewater, much attention has been focused on the use of electrochemical process. This bench-scale study was conducted on synthetic wastewater samples containing organic phosphorus using a closed batch system. The effects of reaction time and initial concentration of organic phosphorus on the electrochemical process of phosphorus removal were studied. In this study, the effect of steel electrodes, an electric current of 0.6 A, a reaction time of 10-60 minutes and also the initial phosphorus concentrations [2 to 32 mg/l] were investigated. The results of this study showed that the concentration of residual organic phosphorus after the electrochemical process at different initial concentrations was reduced to less than 1 mg/l [equivalent to the effluent discharge standard to receptive water in Iran] at a reaction time of 50 minutes. Moreover, the phosphorus removal efficiency was between 93.73-98.72% at different initial concentrations and a reaction time of 60 minutes. The electrochemical process, using the steel electrodes at an electric current of 0.6 A, can reduce the phosphorus concentration to less than 1 mg/l. Moreover, the optimum reaction time for the removal of organic phosphorus is 50 minutes

[Evaluating the corrosive and scale-forming indices of water in the villages under the coverage of Kashan rural water and wastewater company during 2007-9]

Background: Kashan rural water and wastewater company [KRWWC] in Iran is facing a multitude of problems including some potential health risks associated with pipe corrosion byproducts, their early deterioration, the occasional interruption of the water supplies and also huge operation costs. Therefore, this study aimed to evaluate the corrosive and scaleforming properties of water in Kashan villages

Materials and Methods: This descriptive study was carried out on 151 water samples taken from 39 rural water supplies in 4 stages during 2007-9. All samples were analyzed for total hardness, calcium, alkalinity, total dissolved solids [TDS], bicarbonate, temperature and pH according to the last edition of the Standard Methods Book and then Ryznar, Langelier and Puckorius indices were calculated. Data were analyzed using Fisher's exact test and Paired ttest followed by Bonferroni correction

Results: According to Ryznar, Puckorius and Langelier indices, 95%, 97% and 74% of the water supplies in all seasons were corrosive, respectively. Moreover, according to the three above-mentioned indices, 18 villages [46.15%] under the coverage of Kashan rural water and waste water company have always had corrosive water and there was also no significant difference in water quality between the seasons

Conclusion: Results showed that most water supplies are corrosive and a few of them are scale-forming. Hence, application of suitable plumbing utensils, turn on/off bypass pumps and valves and if necessary, appropriate water treatment are recommended

Application of flat plate solar collector for thermal disinfection of wastewater effluents

Application of solar energy for wastewater treatment has shown to have the least negative effects and costs. This experimental research was carried out in pilot-scale on the effluent of the extended aeration activated sludge wastewater treatment system in Kashan. The plant is located at the Kashan University of Medical Sciences campus and receives about 100 m[3]/d sewage from official and residential building blocks. In this study thermal disinfection of the effluent in 55 Degree C for 2 hours using flat plat solar collector [FPSC] was investigated. During the study in the beginning of every week, one day was selected randomly and the pilot was run. The pilot influent temperature was the same as ambient air throughout the day. If the liquid temperature within the pilot increased above 55 Degree C, a thermostatic valve opened. Passed liquid was maintained for 2 hours in this temperature. Whenever the volume of disinfected effluent was measurable fecal MPN test and Nemathoda eggs count-up were done according to the Standard Methods and Leeds-II directions, respectively. In 200 days from April to November the geometric mean of fecal coliform never exceeded the WHO guideline [1000 MPN/100mL], but in 5 days [21%] it exceeded the Iranian standard [400/100mL]. Mathematical mean of Nemathoda eggs was less than 1 per liter [Engelberg Index] persistently. The mean of hydraulic loading rates was calculated 83.25 L/d m[2] while it decreased to 41.85L/d.m[2] in the days without thermal reclamation

[Chemical quality evaluation for the inlet and outlet water taken from of the desalination plants utilized in Kashan during 2008]

Background: Quality control of drinking water is important for healthy consumers. Having a high total dissolved solid [TDS] in water causes a salty taste. Reverse osmosis is one among the membrane processing methods currently used for lowering TDS in water. As during the recent years several desalination plants were set into operation by private sectors in Kashan, the study was carried out for the evaluation of the quality control of inlet and outlet water of the mentioned plants

Materials and Methods: This cross-sectional descriptive study was carried out using samples taken from the inlet and outlet water of plants during a six-month period in summer and winter seasons of the year 2008. A total number of 128 samples taken from 16 desalination plants were analyzed for water chemical quality

Result: The average concentration of chemical parameters in treated water were: TDS= 245, total hardness=118, nitrate=2.5 mg/l, fluoride=0.2 mg/l, sulfate=24 mg/l, chloride=63 mg/l and pH range = 6.8-7

Conclusion: Based on findings on desalinated water, except for fluoride, other parameters were in accordance to the optimum concentration for drinking water. For the prevention of dental caries, addition of fluoride should be considered in future program. While pH of outlet water was relatively decreased with respect to the raw water, but none of them were compatible with drinking water standards