Secondary clarifiers form a crucial component in gravity separation processes mainly in solid-liquid separation. They perform the crucial process of separating the activated sludge from the clarified effluent and also to concentrate the settled sludge. As treatment plants receive increasingly high wastewater flow, conventional sedimentation tanks suffer from overloading problems which result in poor performance. Inlet baffle modification by using an energy dissipating inlet (EDI) was proposed to enhance the performance in the circular clarifiers in Al-Dewanyia wastewater treatment plant. A 3-Dimensional fully mass conservative clarifier model was applied to evaluate proposed tank modification and to estimate the maximum capacity of the existing and modified clarifiers. A Computational Fluid Dynamics (CFD) model was formulated to describe tank performance and design parameters were obtained based on the experimental results. The study revealed that velocity and SS are better parameters than TS, BOD5, and COD to evaluate the performance of sedimentation tanks. Removal efficiencies of suspended solids, biochemical oxygen demand, and chemical oxygen demand were higher in the EDI (Baffle).
Constructing and testing a microbial fuel cell, (MFC) was accomplished in this research. Two chambers MFC connected with salt bridge was operated and studied using synthetic and real wastewater as anode chamber solution. Operating temperature and pH value were investigated by changing temperature from 25 OC to 30 OC and varying pH from 6.7 to 6.5. The results reveled that increasing operation temperature had a significant effect on reducing operation time while decreasing pH improved the measured voltage and current besides reducing operation time to just five days. The cell was tested with the presence of real wastewater under the optimal temperature and pH and the results proved the capability of the manufactured cell in treating such contaminate in relatively short operation time. The COD reduction rate was above 60% indicated the ability of living microorganisms in digesting the wastewater producing electrical power with maximum values of 0.443 mV and 8.3 μ A for voltage and current, respectively.
ABSTRACT. Hospitals pose a significant risk to human health due to the contamination of their environment with chemical elements. Exposure to these elements can have adverse health effects, such as neurological and developmental problems, cancer, and endocrine disruptors. To prevent and mitigate the risks associated with contamination, it is important to identify and control the sources of contamination. This study intends to investigate how chemical elements are contaminating hospitals, including the sources of contamination, possible health impacts of exposure, and preventative and remedial actions that may be done to lessen the dangers. To reach the aims of this study, water samples from three different spots at two different seasons (winter and summer) of the water flow through the hospitals (Hospital water on its first entry inside, Wastewater after use inside and around the hospital and Wastewater after passing through the treatment unit inside the hospital) have been collected. Magnetic suspended matter (TS), Total materials (T.D.S), Electrical Conductivity, and Turbidity tests have been done to the collected water samples. Additionally, heavy materials have been detected in the collected samples. The results showed that the pH function increased slightly and insignificantly for the alkaline after using the water, while the water conductivity, Alkalinit, hardness, and percentage of suspended solids (T.S.S) and dissolved solids (TDS) reached the highest in wastewater. From the results of this study, we can conclude that the stages of treatment are slow and inefficient.
Chlorine contact tank in water and waste water treatment plant suffer from a lack of efficiency disinfected treated water, which discharge to the rivers and they need a large amount of chlorine for the purpose of disinfection as a result of the presence of dead zones in the basins of chlorine as well as the need to contact a long more than exact standard specifications for the tanks disinfection time. This study deal with optimal performance basin mixing chlorine, which is located at the beginning of Chlorine contact tank of waste water treatment plant in the city of Nasiriyah in Dhi Qar, which is located south of the province of Iraq. In this paper, the use of computational fluid dynamic model in the numerical analysis for the purpose of finding the optimum performance of the chlorine mixing tank with the help of the program FLUENT 6.3.26 and program GAMBIT 2.3.16. Also in this study was used User Defined Function for the purpose of improvements of mixing chlorine. Where the results of the study showed that the ideal rotational speed of the mixer is 140 rpm as well as the results showed Numerical Model that can reduce chlorine dose to 5 mgliter, which is the optimum concentration of chlorine to be supplied for wastewater disinfect and is identical to the Iraqi specifications water sanitation, which discharge to the Euphrates River. In this study the best contact time of chlorine which give the best performance for mixing was 20 seconds.
Activated sludge process is considered one of the most common and highly effective methods used in aerobically biological treatment systems. The design of such systems is usually based on the biological kinetic approach considerations. The present study is concerned in determining the biological kinetic of the last part of Diyala River at AL-Rustimiyah WWTP's, Baghdad, Iraq. A completely mixed continuous flow lab-scale reactor without recycling was used for this purpose. Various detention times were adopted during the experimental work ranging from 0.723 to 3.809 days. Influent and effluent BOD5, MLVSS and MLSS for the aeration tank, among other tests were performed at different detention times, after reaching the steady state conditions, in order to generate the required data for bio-kinetic coefficients. The biological kinetics k, Y, Kd, and Ks for the last part of Diyala River at AL-Rustimiyah WWTP's were found to be 5.68 d-1, 0.75, 0.06 d-1, and 70 mg/l, respectively. These values were compared with the bio-kinetics of different types of wastes and were found to be within the typical ranges of bio-kinetic parameters for activated sludge process treating domestic wastewater, which indicates that the water at the river reach of interest is rather wastewater than pure river water.
The concern over increasing needs for drinking water and awareness for development of systems to improve water quality both for drinking purposes and for effluents from wastewater treatment and industrial facilities have provided incentives to develop new technologies and improve performance of the existing one. Adsorption technology has many advantages over other treatment methods such as simple design, low investment cost, limited waste production, etc. Synthetic water with a dosing of artificial copper solution (Cu No3) was passed through a PVC column (15 cm diameter, 100 cm length) containing limestone as a filter media in three different sizes, using three different hydraulic rates, and three initial influent copper concentrations (7.04, 4.39, 1.72) ppm .For this study, three experiments have been conducted; continuous batch and field experiment. The up flow roughing filtration is the suitable technique to recover heavy metals present in aqueous solutions, without the need of adding further substances. The filtration results demonstrated that the smaller size of filter media (3.75) mm gave higher removal efficiency (93.75 – 98.80) % than larger filter media (9.50) mm which gave removal efficiency of (67.61 – 94.0) %. This is due to the large specific surface. The smaller size of limestone achieved the longer detention time (49) min, so the removal of Cu was more than (90) % for the (50) min of experiment. At lower flow rate (0.16) L/min, the removal efficiency was higher than at higher flow rate (0.77) L/min. At high flows, there is a reduced period of surface contact between the particles and copper solution. This study also involved three different batch experiments .The removal efficiency was (93- 97) % for the three types of limestone which indicates the importance of limestone media in the removal process. This also indicates that the removal efficiency was increasing with the increase of the limestone volume. Field experiment has been conducted using wastewater from Al- Dura Electric Station on the three types of limestone so that to ensure the laboratory tests. It was achieved good removal efficiency range from (87.5) % to(97.5) % at the high adsorbent dose .To calibrate the physical model, a computer program of multiple regressions is used to assess the relative importance of the predicted variables. The partial correlations indicate that influent concentration of copper, surface loading (flow rate), and detention time are the most important variables while the size of limestone is not important as others.
In this paper three material with equal amount have been chosen to make a mixture, these materials are sand (passing sieve no. 1.18, porosity 0.41), activated carbon (passing sieve no. 4.75, porosity 0.51), crushed bricks (passing sieve no. 20, porosity 0.47), the mixture was used as a bio-filtering media , placed to a height of (1.15) m in a cylindrical filter with diameter of (300)mm and a height of (2)m which is designed and constructed from (PVC). The filter is equipped with three piezometers fixed at three point along the height of the cylindrical filter, in addition to three overflows at different height, and an outlet with control valve. On May 2010 the filter was operated with a synthetic wastewater similar to domestic sewage in order to determine the hydraulic and sanitary characteristics of the filter. Then the feeding of waste water was continued for 3 weeks in order to stimulate the growth of bio-film. On June 2010 the filter was operated with gray water to determine the change in filter characteristics after the bio-film growth, and to evaluate filter efficiency to treat this water for the purpose of reuse. The outcome of this work showed that the mixed media bio-filter, to a certain extent, is similar in hydraulic characteristics (pressure drop and hydraulic load) to granular activated carbon bio-filter, head loss at (1000) mm depth is (59%) of initial pressure, the growth of bio-film leads to increase in head loss by (43%), decrease in flow by (25|%), decrease in pressure by (16%). According to removal efficiency of pollutants, the results shows an efficient removal of BOD5 (86%), turbidity (96%), TDS (81%) at a retention time (60 minute).
Removal of reactive red dye (Cibacron Red FN-R) from simulated wastewater has been investigated as a function of solar advanced oxidation process. The photocatalytic activity using ZnO as a photocatalyst has been estimated. Different parameters affected the removal efficiency, including pH of the solution; initial dye concentration and H2O2 concentration were evaluated to find out the optimum value of these parameters. The results proved that, the optimal pH value was 8 and the most efficient H2O2 concentration was 100mg/L. Reduction of organic content for effluent solution was also monitored by measuring chemical oxygen demand (COD) to assess the degradation process. This treatment method was able to strongly reduce the organic content of reactive red dye-238 to 90% while the colour removal was 99%. It can be concluded, from these experiments, that the using of ZnO as a photocatalysis was exhibited as economical and efficient treatment method to remove reactive red dye-238 from aqueous solution by reducing its colour and COD value. Results were properly fitted to LH model.
The current study includes application of QUAL2K model to predict the dissolved oxygen (DO) and Biochemical Oxygen Demand (BOD5) of lower reach of the Diyala River in a stretch of 16.90km using hydraulic and water quality data collected from Ministry of Water Resources for the period (January-April 2014). Google Earth and Arc-GIS technique were used in this study as supported tools to provide some QUAL2K input hydro-geometric data. The model parameters were calibrated for the dry flow period by trial and error until the simulated results agreed well with the observed data. The model performance was measured using different statistical criteria such as mean absolute error (MAE), root mean square error (RMSE) and relative error (RE). The results showed that the simulated values were in good agreement with the observed values. Model output for calibration showed that DO and CBOD concentration were not within the allowable limits for preserving the ecological health of the river with range values (2.51 - 4.80 mg/L) and (18.75 – 25.10 mg/L) respectively. Moreover, QUAL2K was used to simulate different scenarios (pollution loads modification, flow augmentation and local oxygenation) in order to manage the water quality during critical period (low flow), and to preserve the minimum requirement of DO concentration in the river. The scenarios results showed the pollution loads modification and local oxygenation are effective in raising DO levels. While flow augmentation does not give significant results in which the level of DO decrease even with reduction in the BOD5 for point sources. The combination of wastewater modification and local oxygenation (BOD5 of the discharged effluent from point sources should not exceed 15 mg/L and weir construction at critical positions 6.67km from the beginning of the study region with 1m height) is necessary to ensure minimum DO concentrations.