Hasil untuk "Sewage collection and disposal systems. Sewerage"

Donya Ansari Moghadam, Reza Marandi, Shahrzad Khoramnejadian et al.

The problem of toxic-metal-contaminated water has become a great environmental concern and presents significant hazards to the public health and economy. In this study, drinking water treatment sludge was activated and used as an efficient, cheap and cost effective sorbent in the removal of Pb (II) ion from water samples. The prepared material was characterized by Fourier transfer infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), scanning electronic microscopy (SEM), surface analysis (BET method) and X-ray fluorescence (XRF) analysis. The effects of various parameters such as the solution pH, adsorption time, adsorbent dosage, and initial metal ion concentration upon adsorption were investigated. Equilibrium isotherm studies were carried out with different initial concentrations of Pb (II), and three models (Langmuir, Freundlich and Temkin isotherms) were utilized to analyze the equilibrium adsorption data. The best adsorption performance was obtained at the following conditions: pH of sample, 7.5; contact time, 15 min; adsorbent dosage, 0.3 g; intitial concentration of Pb (II), 20 mg/L; agitation speed, 200 rpm. The results revealed that the adsorption process obeyed the Langmuir model, with the maximum monolayer capacity (qmax) and the Langmuir constant (KL) calculated as 54.9 mg/g and 0.973 mg/L, respectively. Kinetic studies indicated that the adsorption process followed a pseudo-second-order model based on the obtained R2 values. Comparison study with the other natural adsorbents revealed that the activated sludge has the highest adsorption capacity and provides the lowest adsorption time. Desorption study exhibited that the Pb (II) ions can be desorbed from the adsorbent by 0.25 mol/L HCl solution with a recovery percentage of 98%. The results exhibited that activated sludge is an efficient and cost-effective material for the adsorption of Pb (II).

Fazel Ghobaishavi, Ahmad Akbari, Amir Dadras Moghadam et al.

One of the most serious threats to many countries is water pollution caused by the use of fertilizers and chemical pesticides in agriculture. Limited research has been done in this field in Iran. Spatial dimension and disparity between provinces have not been considered. This research has been conducted in the unique Framework of Environment Kuznets Curve (EKC), to investigate the relationship between urbanization, water pollution and economic growth during the years 2011-2019 in 30 provinces of Iran. First, the stationary test of the variables was performed and then before estimating the model, diagnostic tests were used to ensure the existence of a spatial correlation relationship between the variables using the spatial panel approach. Levin, Lin, and Chou stationary tests showed that all variables were at the mana level. Moran, Jerry, and LM Lag (Robust) diagnostic tests then confirmed the existence of spatial dependence and the Spatial Durbin model. The results of estimating the Spatial Durbin model show the urban population with a coefficient of 54.07 and the square of the urban population with a coefficient of -0.004 and the overflow effects of these variables with coefficients of 0.054 and 0.000004, respectively, in the provinces of Iran. Water pollution index has a positive and negative effect, which indicates the confirmation of the Environmental Kuznets Curve hypothesis (KEC) in the field of water pollution in the provinces of Iran. With the expansion of urbanization and economic growth, the water pollution index has increased, but when there is a certain amount exceeds, the water pollution index due to the use of pesticides and chemical fertilizers in a province and adjacent provinces. It is suggested that agricultural policy makers make the use of organic fertilizers instead of chemical fertilizers mandatory to control water pollution in all provinces of Iran.

Sasan Fooladivanda, Mohammad Ghorbanpour, Mohammad Bagher Moghimi

Today, industrial and sanitation wastewater production and their penetration into water resources have caused numerous challenges. Moreover, limitations on water resources used in industry, agriculture, drinking water, and wastewater have led human societies to make optimal use of available resources and treat the polluted water. This study investigated the effect of the acid and alkaline activation methods on dye adsorption by red clay. Each activated soil was used to remove methylene blue paint by adsorption method to determine the activated soil with the highest efficiency. The influential factors on adsorption, including the effects of solution pH (5-11), dye concentration (100-100 mg/L), and the amount of adsorbent (0.3-0.2 g) in adsorption of methylene blue dye, were examined on the optimal adsorbent, and the optimal conditions were investigated and determined. Then, X-Ray diffraction, measurement of porosity and effective surfaces, and Fourier transform infrared analysis were used to study the physical, chemical, and morphological properties. The results of chemical analysis showed that the soil activated with 3 M acid has the highest adsorption capacity among other activation methods. According to the detection analyses, the surface area of the clay increased after the acid activation operation due to  some of the bonds in the structure of the clay breaking (results of Fourier transform infrared) and the opening of the plates (scanning electron microscope images). These factors increased the uptake of activated soil significantly (27 to 81%) compared to raw soil. The adsorption behavior of the adsorbent showed that the adsorption isotherm is consistent with the Langmuir equation model. The results of the reusability study showed that the adsorbent is reusable. Results also showed that the modified soil is an effective adsorbent to remove methylene blue from aqueous solutions.

Hamid Roshanravan, Seyd Mehdi Borghei, Amir hesam Hassani et al.

Nitrate removal using biological heterotrophic denitrification is one of the most effective and economical processes to remove nitrate from drinking water. In recent studies, carbon sources such as acetic acid, methanol, ethanol, glucose, etc. have been used as a carbon source for heterotrophic bacteria. Inevitable residues of these carbon sources in effluent water and the cost of them are the key challenges for applying these carbon sources in drinking water, in the operational scales. To overcome these challenges, in this research, citric acid produced from sugar beet is used as a harmless, relatively economical and accessible carbon source. Also, to remove the remaining trace amounts of carbon source in denitrified water and disinfection of treated water, ozonation has been used as a dual-purpose process. Pilot studies of this process during the operation of about one year on natural water of one of the wells of North Khorasan province in Iran with the nitrate concentration of 104±10 ppm ppm as NO3- showed that in four column bioreactor packed with different media such as natural river gravel, polypropylene plastic (PP), polyethylene plastic (PE) and Pumice aggregates and by carbon to nitrogen ratio (C/N) of about stoichiometric amount and HRT of greater than 4 hours and without any other chemical addition, the nitrate removal rate of greater than 85% can be achieved. In the carbon concentrations, about 1.5 times the stoichiometric value and the HRT of about 5 to 7 hours, the removal efficiency can be as high as 95%. Ozonation of treated water in 30 to 60 minutes also showed that the ozone has the capability of the complete removal of carbon residuals in effluent of the process from 15-30 ppm as COD to about zero.

Mehdi Hayati, Somayeh Tourani

Removal of contaminants by adsorbent is a useful and effective way to remove heavy metals from wastewater and aqueous samples. Mercury is one of the heavy metals that is toxic to humans, animals and the environment. In this study, magnetic multi-walled carbon nanotube (MMWCNT) composite was synthesized and used to remove Hg(II) from aqueous solutions. This work was conducted on a laboratory scale and based on the design of experiment by the surface response methodology (RSM) and based on Box-Behnken design, and the effects of independent variables including pH, adsorbent dose, initial concentration of Hg and contact time in different levels were evaluated with the help of Design-Expert Stat-Ease Inc software. The properties of this magnetic adsorbent were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The results show that the adsorption of Hg(II) on magnetic MWCNT composite is strongly dependent on contact time and adsorbent dosage. The highest efficiency of removal mercury was about 85% and that occurred when pH=6, dose of adsorbent= 0.6 g/L, initial concentration of Hg(II)=10 ppm and contact time=150 minutes. The adsorption isotherm data were better fitted by Freundlich model, while kinetic data can be characterized by the pseudo-second-order rate kinetics. In general, it can be concluded that magnetic MWCNT adsorbent has a very high ability to remove mercury.

Negin Nasseh, Behnam Barikbin, Lobat Taghavi et al.

Antibiotics are organic pollutants that are introduced into surface water and underground water sources due to urban and industrial effluents. Due to their high stability, they do not only disrupt the common processes of sewage treatment, but also have toxic effects on humans and other living organisms, and their removal have therefore been considered. This is an experimental study in a laboratory scale with the aim of evaluating the efficiency of the new FeNi₃/SiO₂/CuS magnetic nanocomposite for the decomposition of metronidazole in the presence of H₂O₂ as a heterogeneous Fenton- like catalytic process in aqueous solutions. In present study, firstly, this nanocomposite was synthesized and characterized by FESEM, TEM, FTIR, XRD and VSM. This study, which was performed on synthetic sewage in batch system, parameters such as pH (3, 5, 7, 9 and 11), nanocomposite dose (0.005- 0.1 g/L), metronidazole concentration (10-30 mg/L) and the concentration of hydrogen peroxide (50-200 mg/L) at ambient temperature was investigated. The obtained results showed that the highest percentage of removal of metronidazole in pH =7, nanocomposite dose (0.1 g/L), hydrogen peroxide concentration of 150 mg/L for 20 mg/L contaminant concentration at time of 180 minutes, 77.92%. Also, the kinetic rate of degradation flowed pseudo-first-order equation (R2=0.95) and the degradation constant rate of this reaction is 0/0038 (1/min). Based on the results obtained from this study, it can be concluded that Hentrogenase Fenton like catalytic process has a very good effect in removing metronidazole antibiotic contamination from aqueous solutions.

Marzieh Hosseininasab, Roohollah Rezazadeh

Water plays a vital role in mineral processing as evidenced by the approximately 2 to 3 tons of water used for the treatment of one ton of ore. A major portion of this water may be recovered in thickeners. This study aimed to control the wet tailings output of the Hematite Gol-e-Gohar plant by changing  flocculant dosage and type and solid percentage in the feed in order to enhance effluent clarity and reduce water consumption. Materials and A series of settling experiments were performed using different combinations of the flocculants (A25, A26 Yazd, A26 Esfahan, A27, and A28), flocculant doses (20, 25, 30, 35, and 40 gr/ton), and solid loads in the feed (5, 7, 9, 10, and 11%) to the thickener. The L25 Taguchi design method was chosen to handle the five different levels of the three factors. Adopting a 95% confidence interval, the results of analysis of variance (ANOVA) revealed that flocculant consumption rate had a high effect on settling velocity (p = 0.006) while flocculant type and solid percentage in the feed had no significant effects. Moreover, it was found that A26 (Akhtar-chemistry Company, Yazd) used at a rate of 40 g/ton improved the settling performance to yield an optimal water clarity. Using the findings of this study in process planning at the plant led to a considerable reduction (from the original 0.86 to 0.49 m3) in average water consumption per ton of input material so that the solid content of the thickener underflow rose from 7 to 45%.

Rezvan Birooni, Masoumeh Mirzaei

This study is an experimental investigation of sulfate removal efficiency using iron nanocomposites on graphene oxide and activated carbon beds. The graphene oxide used was synthesized according to the Hummer method during which process graphene oxide and activated carbon were added. The effects of various parameters including adsorbent content, pH, and contact time on adsorption were investigated. Furthermore, the data were subjected to kinetic studies. Results revealed that the highest absorption rates of 84% and 62% were achieved for iron on the graphene oxide and activated carbon beds, respectively, when 0.06 g of the adsorbent was used at pH =11 over a contact time of 9 hours. It was also found that the kinetic pseudo-second-order model best fit the data. Finally, the results indicated that the two environmentally-friendly adsorbents have a good potential for removing sulfate from aqueous solutions.

Neda Masoudipour, Mehraban Sadeghi, Mohsen Behpour et al.

This paper investigates cyanide photodestruction (at pH 9) using the S, N-TiO2 photocatalyst synthesized by the sol-gel method and stabilized on glass microbeads. The main raw materials were thiourea, as a source of N and S, and tetra butyl ortho titanate. The effects of S and N doses, visible light (a 400W light), sunlight, irradiation time, and different initial cyanide concentrations (50, 100, 200, and 300 ppm) were studied on cyanide photodestruction. Cyanide concentration was measured by the titration method and the photocatalyst film was characterized by X-ray diffraction (XRD), UV-Vis diffuse reflection spectroscopy (DRS), Scanning Electron Microscopy (SEM), and Energy dispersive X-ray (EDX) analysis. XRD patterns and SEM images were used to determine the nanoparticle size of the photocatalyst on glass microbeads. EDX and DRS analyses confirmed the presence of S and N as well as the activity of the photocatalyst in the visible region, respectively. The S, N-TiO2 film with 0.25 g Thiuourea proved to be the best cyanide photodestruction agent in the visible light. Based on the results obtained, S, N-TiO2/ glass microbead was capable of destroying cyanide (50 ppm) by up to 94% in the visible light and by approximately 100% in the sunlight. The results also indicated that S, N-Tio2/scoria stone was capable of destroying cyanide by 85% in the visible light and by 94% in the sunlight within 4 h.  The reaction kinetic for all cyanide concentrations and two photocatalyst substrates were described by a first order equation. Finally, it was concluded that the S, N-TiO2 stabilized on glass microbeads could be effectively used as a new method for treating wastewater containing free cyanide under the sunlight.

Mohsen Keshavarz Tork, Ahad Ghaemi, Mansour Shirvani

In this study, the extraction of phenol from wastewater was simulated using intelligent methods which include multi-layer perceptron, radial basis functions network, and support vector regression. To design the network structure and to train and test it, 184 experimental data sets were used. Inputs to the network consisted of organic–aqueous volume ratio, rotor speed, temperature, pH, and time while extraction efficiency was the output. Root mean square error and correlation coefficient were used in all the three models as network performance and network stop criteria. Comparison of the results obtained from the three models revealed that the support vector regression was the best model with a correlation coefficient of 0.684 and a root mean square error of 0.99. Moreover, model results showed good agreement with experimental data. Optimal process operational parameters included an organic to aqueous volume ratio of 0.22, a rotor speed of 350 rpm, a temperature of 22.86 °C, a pH equal to 7.5, and an agitation time of 15.86 minutes; the corresponding extraction efficiency was obtained to be 96.35.

Alirezi Rahmani, Amir Shabanlo, Saba Majidi et al.

A newly emerging environmental problem is the discharge of pharmaceutical effluents containing antibiotic compounds. Compared to common methods, the ozone/persulfate process is a novel measure for treating persistent pollutants. This process is highly efficient in removing pollutants by using the free radicals of sulfates as powerful oxidants. In this study, a semi-continuous reactor with a useful volume of 1 L was used to evaluate the performance of the ozone/persulfate process in treating the ciprofloxacin antibiotic at concentrations from 10 to 100 mg/L in the presence of 0 to 15 mM of persulfate in 30 min. The results showed that under the optimized operating conditions of pH = 3, persulfate dose = 10 mM, ozone dose = 1 g/h, and an initial antibiotic concentration of 10 mg/L, this method was capable of removing 96% of the contaminant. Moreover, the efficiency of the process was found to be a function of experimental conditions. Based on the results of this study, it may be concluded that the ozone/persulfate process can be considered as an appropriate process for treating persistent and non-biodegradable pollutants.

Lale Divband, Saeid Broomand nasab, Pooya Shirazi et al.

The objective of this study was to determine the efficiency of lead removal from aqueous (both single- and multi-element) solutions using the nanostructured ash cedar absorbent. Nanostructured ash cedar was synthesized and the effects of pH, absorbent dosage, and contact time on lead removal efficiency were investigated in a batch system. The absorbent was characterized by SEM, PSA, XRF, and FTIR. SEM results showed that all the particles had diameters smaller than 207 nm. It was also found that the optimum pH values for lead adsorption were 6 and 5 for the single-element and the multi-element systems, respectively. The maximum removal efficiencies of 94% and 98% and maximum adsorption capacities of 27 mg/g and 21 mg/g were obtained for the single- and multi-element systems, respectively. Comparison of the Freundlich, Langmuir, and Sips isotherms showed that the Langmuir model with R2 =0.99 and RMSE = 1.01 for the single element system described the adsorption data better than other models did. Also, this model with R2 = 0.99) and RMSE = 0.024 better fitted the adsorption data in the multi-element system.

Noushin Birjandi, Habibollah Younesi, Nader Bahramifar et al.

Paper-recycling wastewaters have high volume and high pollution and its treatment is the most difficult and complicated process because of their colored pollutants and certain rigid chemical structure. In this study, the efficiency of alum in coupled with polyaluminum chloride (PACl) coagulant on the treatment of paper recycling wastewater was investigated. The effects of initial pH, initial COD and coagulation concentration on sludge volume index (SVI), and turbidity and COD removal were studied. Set tested for coagulation process was 2-12 initial pH, 200-2000 mg/l of alum concentration, 50-1500 mg/l of PACl concentration and 250- 2250 mg/l initial COD. According to the data obtained from batch studies, maximum percentage removal of turbidity and COD 89.90% and 85.16% respectively. The SVI of 193 ml/gr was found in this study. This study showed that the alum and PACl coagulants have high ability to remove pollutants from wastewater factory.

Kazem Nadafi, Mehdi Fazlzadeh Davil, Amirhossein Mahvi et al.

Corrosion is one of the main problems of sewers around the world which causes huge quantities of both economic and ecological damages. Biological corrosion accounts for 20% of the total microbiological corrosion worldwide. The purpose of this study was to determine the corrosion potential in Ray sewers by H2S and ORP borne by wastewater. In this survey, H2S and Oxidation-Reduction Potential (ORP) were measured using a portable H2Smeter (MICRO III mark, model G203s) and a portable ORPmeter (mark Hana), respectively. The results were subsequently compared with those of CCTV (model IBAK) visual observations. The mean values of H2S in the sewers were found to be 0.83 ppm with a standard deviation of 0.931 at 9 a.m. and 1 ppm with a standard deviation of 1.155 at 3 p.m. Also, the mean values of ORP were -8.42 mV with a standard deviation of 60.43 at 9 a.m. and -37.3 mV with a standard deviation of 66.85 at 3 p.m. Based on the amounts of H2S and ORP produced in Ray sewers and also the results obtained from CCTV visual observations, the corrosion potential of wastewater in these sewers was judged to be considerably high.

Ahmad Reza karimipour, Gholam Reza Rakhshandehroo

In this study, hydraulic behavior of Shirazplain aquifer, with an area of ~300 km2, was simulated using PMWIN model. The performance of recently constructed drainage system in the plain was modeled and parameters affecting hydraulic behavior of the aquifer were analyzed. Measured rainfall and evaporation rates in the plain, recharge and discharge rates through the aqueducts, Khoshk and Chenar Rahdar rivers, as well as amount of water discharged from production wells and recharge due to returned wastewater were considered in the model. Plain hydrodynamic coefficients were estimated via calibration and sensitivity analysis of the model was performed for four important parameters. Results showed that the model is most sensitive to recharge rate and hydraulic conductivity, respectively, such that a small variation in these two parameters causes a dramatic change in hydraulic head distribution in the plain. Furthermore, specific yield coefficient influences the seasonal water level fluctuations, but the aqueducts conductance coefficient only affects the aqueduct radius of influence with little effect on the overall hydraulic behavior of the plain.

Fatemeh Rastegaripour, Mahmood Sabouhi Sabouni

The present study investigates water allocation of Kardeh Reservoir to domestic and agricultural users using an Interval Parameter, Multi-stage, Stochastic Programming (IMSLP) under uncertainty. The advantages of the method include its dynamics nature, use of a pre-defined policy in its optimization process, and the use of interval parameter and probability under uncertainty conditions. Additionally, it offers different decision-making alternatives for different scenarios of water shortage. The required data were collected from Khorasan Razavi Regional Water Organization and from the Water and Wastewater Co. for the period 1988-2007. Results showed that, under the worst conditions, the water deficits expected to occur for each of the next 3 years will be 1.9, 2.55, and 3.11 million cubic meters for the domestic use and 0.22, 0.32, 0.75 million cubic meters for irrigation. Approximate reductions of 0.5, 0.7, and 1 million cubic meters in the monthly consumption of the urban community and enhanced irrigation efficiencies of about 6, 11, and 20% in the agricultural sector are recommended as approaches for combating the water shortage over the next 3 years.

Saeideh Kheradmand, Ayoub Karimi Jashni, Parviz Monadjemi

Degradation of the organic part of landfill in along with rainwater percolation produces a polluted liquid named "leachate", which poses a considerable hazard to the environment because of its toxic and hazardous compounds. In this research, the treatability of leachate was investigated using combined anaerobic digesters. Each digester had an effective volume of 150 l, a flow rate of 10 l/d, and a HRT of 15 d working at a temperature of 31°C (mesophilic). The OLR applied to the system was gradually increased from 0.07 to 3.4 g/l.d in 5 steps. TCOD concentration was 48552-62150.4 mg/l and BOD5/COD ratio was more than 0.7 during the study period. At an OLR of 2.2 g/l.d, the total maximum COD removal efficiency achieved in both digesters was 93.59%. Not only did ammonia concentration not reduce in the anaerobic system but it increased. Ammonia concentrations at optimum OLR in the influent to the 1st and 2nd digesters were 721, 952, and 1054 mg/l, respectively. Maximum biogas production was 9.823 l/day in the 1st digester and 6.298 l/day in the 2nd digester, both of which occurred at an OLR of 3.4 g/l.d.

Hassan Khorsandi, Bijan Bina, Mohammad mehdi Amin

Humic substances have been known as precursors to disinfection by-products. Because conventional treatment processes cannot meet disinfection by-product standards, novel methods have been increasingly applied for the removal of disinfection by-products precursors. The UV/TiO2 process is one of the advanced oxidation processes using the photocatalytic technology. The most important advantages of this process are its stability and high efficiency removal. The present study aims to investigate the effect of UV/TiO2 photo-catalytic technology on removal of humic substances. The study was conducted in a lab-scale batch photo-catalytic reactor using the interval experimental method. The UV irradiation source was a low pressure mercury vapor lamp 55w that was axially centered and was immersed in a humic acids solution within a stainless steel tubular 2.8 L reaction volume. Each of the samples taken from the UV/TiO2 process and other processes studied were analyzed for their dissolved organic carbon, UV absorbance at 254nm, and specific UV254 absorbance. The results indicated the high efficiency of the UV/TiO2 photo-catalytic process (TiO2=0.1 g/L and pH=5), compared to other processes, for humic substances removal from water sources. The process was also found to be capable of decreasing the initial dissolved organic carbon from 5 to 0.394 mg/L. The Specific UV254 Absorbance of 2.79 L/mg.m was attained after 1.5 hr. under photo-catalytic first order reaction (k= 0.0267 min-1). It may be concluded that the UV/TiO2 process can provide desirable drinking water quality in terms of humic substance content.

Marjan Ghanbarian, Amir Hossein Mahvi, Ramin Nabizadeh et al.

The nanophotocatalytic process using nano-structured semiconductors is one of the techniques used for the destructive oxidation of organic compounds such as dyes. The photocatalytic oxidation of Reactive Orange 16 aqueous solution, applied in the textile industry, was assessed by UV ray irradiation in the presence of TiO2 nanoparticles. It was found that the photons required for the process were completely absorbed when TiO2 concentration reached 0.4 g/L. Degradation of paint decreased with increasing TiO2 concentration. It is suggested that at very high concentrations, the active points on ions are covered and the number of radicals like ˙OH will, therefore, decrease on the surface of catalysts. Another explanation for this state of affairs is that UV screening may have the same function. The negative action of anions may be explained by the reaction of positive cavities accomplished by hydroxyl radicals with anions. This reaction can be described as corrosive for ˙OH and hVB+, which can prolong the process of color removal. The TiO2 in an acidic environment has a positive charge (pH

T. G. Westoll

ABSTRACTThe town of Driffield (in the East Riding of Yorkshire) has several combined‐sewer overflows which cause nuisance during rainfall. A new interceptor sewer has been laid and the sewage‐treatment works has been reconstructed to improve the water quality in the receiving watercourse. The sewerage scheme was mainly constructed using trenchless technology to reduce the risk of ground settlement in the narrow streets and to avoid contamination of the underlying aquifer. The existing biological filters were replaced with a new four‐basin cyclic activated‐sludge plant. This process achieves biological treatment within a single reactor basin which operates typically on six 4‐h cycles per day and without the need for separate primary and final settlement tanks.