Seyed Mehdi Sajjadi
Abstract
Treatment of wastewater is a crucial step in reducing pollution from the textile and dyeing industries. One of the best techniques for dye removal is photocatalytic processes, and TiO2 is frequently employed in numerous wastewater treatment applications. In this study, different adsorption isotherm models ...
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Treatment of wastewater is a crucial step in reducing pollution from the textile and dyeing industries. One of the best techniques for dye removal is photocatalytic processes, and TiO2 is frequently employed in numerous wastewater treatment applications. In this study, different adsorption isotherm models and experimental data from the removal of the methylene blue dye from wastewater by applying GO/TiO2/SiO2 nanocomposite were compared. The correlation coefficient values (R2) for the Langmuir isotherm type 1 (Hanes-Woolf), Temkin, and Freundlich were determined to be, respectively, 0.9957, 0.9823, and 0.9515. Additionally, the R2 values for the Redlich-Peterson, Sips, and Toth isotherms models were 0.9575, 0.9626, and 0.9629, respectively. Therefore, Langmuir isotherm type 1 has the highest R2 and is the best model for surface adsorption of methylene blue on GO/TiO2/SiO2 photocatalyst. As a result, monolayer adsorption was most likely dominating during the adsorption. Furthermore, this photocatalyst proved suitable for lower methylene blue concentrations and systems with lower temperature sensitivity.
Mouhamed Ngounouno Ayiwouo; Felicite Obono Mba; Colins Leprince Kombou; Jules Metsebo
Abstract
This paper assesses the environmental impact of the wastewater treatment plant (WWTP) of the Cameroon Real Estate Company (CRE) camp in the "Cité-Verte" district in Yaoundé (Cameroon) and the causes of its malfunction. The study was carried out in two stages. The first stage consisted of ...
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This paper assesses the environmental impact of the wastewater treatment plant (WWTP) of the Cameroon Real Estate Company (CRE) camp in the "Cité-Verte" district in Yaoundé (Cameroon) and the causes of its malfunction. The study was carried out in two stages. The first stage consisted of describing the wastewater treatment steps of the WWTP, and analyzing the staff interviews in order to determine the causes of malfunction that had been suspected. The second phase consisted of collecting water samples at the entry of the WWTP (P1), inside the WWTP (P2), and at the outlet of the WWTP (P3). This, in order to produce a list of the WWTP's collecting systems, characterize the various types of wastewater (P1 and P2) and the treated wastewater (P3), and then determine the effect of effluent discharges on the environment. Finally, the structural and operational malfunctions of WWTP are identified using the Ishikawa and the Pareto diagrams. The results of water characterization show that the mean values of pH (7.7), EC (1059.3 μS/cm), TDS (524.6 mg/L), T° (23.6 °C), BOD5 (10.8 mg/LO2), NO3- (2.3 mg/L), and fecal coliforms (447.3 CFU/100 mL) are below the acceptable limit values of the Cameroonian standard of treated wastewater discharge. However, the mean values of TSS (269.3 mg/L), PO43- (1661.6 mg/L), K+ (1220.6 mg/L) and Escherichia coli (10133.3 CFU/100 mL) exceed the recommended values set by the Cameroonian standard of treated wastewater discharge. The values of the wastewater parameters at the sampling point P3 are globally lower than those at the sampling point P1 but higher than Cameroon’s standard for PO43- and K+. These results demonstrated that the current system (filters and plants) is appropriate but not optimal. The Pareto diagram reveals that the inadequate plant controls, unfavorable working conditions, lack of maintenance andsystematic control, and outdated equipment represent 20% of the causes responsible for 80% of the WWTP's malfunction. Therefore, the implementation of corrective and preventive measures is essential for better monitoring and determinization of the optimal performance of the WWTP of the CRE camp in the "Cité-Verte".
Kiran D D. Bhuyar; Sanvidhan G. Suke; Vilas S S. Sapkal; Rajendra S S. Sapkal
Abstract
Advanced water treatment methods are needed for good quality of lake water. In this study, the hybrid membrane bioreactor (MBR) and nanofiltration (NF) system was investigated to treat Ambazari lake water. The performance of the hybrid system was checked as removal efficiency of chemical oxygen demand ...
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Advanced water treatment methods are needed for good quality of lake water. In this study, the hybrid membrane bioreactor (MBR) and nanofiltration (NF) system was investigated to treat Ambazari lake water. The performance of the hybrid system was checked as removal efficiency of chemical oxygen demand (COD), total dissolved solids (TDS), biochemical oxygen demand (BOD), and permeate flow rate (PFR). All parameters in the hybrid MBR-NF system were operated batch-wise for 5 h. The COD and BOD removal efficiencies were observed to be 95.67 % and 94.64 %, respectively. TDS removal efficiency was obtained to be 92.33%. The highest TSS removal efficiency was reported to be 36.0 % for airflow rates of 1.0 L/min. The pH variation at different airflow rates was found to be significantly low. Hence, from above information, we conclude that this hybrid system treated Ambazari lake water successfully. The treated water had high quality as good as potable water.
Abdolhossain Mohammadi; Reza Ghazavi; Rohallah Mirzaie
Abstract
The present study investigates the effect of treated wastewater and sludge on some vegetative characteristics of the Nitraria schoberi plant. This study was conducted in a randomized block template using several treatments include five levels of irrigation with wastewater (0, 25, 50, 75, and 100 %), ...
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The present study investigates the effect of treated wastewater and sludge on some vegetative characteristics of the Nitraria schoberi plant. This study was conducted in a randomized block template using several treatments include five levels of irrigation with wastewater (0, 25, 50, 75, and 100 %), two types of soil (arable land and desert soil of Meighan desert area), and two levels of sludge (presence and absence of sludge) with 6 repetitions for each treatment. SPSS software was used to perform the statistical analysis of plant morphological characteristics. The results showed that the highest increase in height, collar diameter, and the crown cover was observed when a wastewater level of 100 % was applied in the catchment basin soil of the Meighan desert at both presence and absence treatment of sludge. However, the same characteristics of Nitraria schoberi plant for cropland soils in the present treatment of sludge were at wastewater level of 100 % and in the absence treatment of sludge for plant height, collar diameter and crown cover diameter were at wastewater level of 50 %, 100 %, and 75 %, respectively. According to the results, different levels of wastewater have a significant impact on Nitraria schoberi plant height and crown cover diameter (P<0.01(. But different treatments did not show a significant difference in the collar diameter of the Nitraria schoberi plant. We can conclude that the use of wastewater should have a favorable effect on plants and soils of the desert area and should protect soil and water resources, but the environmental impact of treatments should be examined.
Hossein Hazrati; Zahra Sadat Sajadian; Nader Jahanbakhshi; Mohammad Rostamizadeh
Abstract
In this paper, the effect of different sludge retention times (SRTs) on membrane fouling of membrane bioreactor (MBR) systems including synthesized ZSM-5 nano-adsorbent was investigated. Three MBRs including nano-adsorbent were applied in SRTs of 10, 50 and 100 d during six months for wastewater treatment. ...
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In this paper, the effect of different sludge retention times (SRTs) on membrane fouling of membrane bioreactor (MBR) systems including synthesized ZSM-5 nano-adsorbent was investigated. Three MBRs including nano-adsorbent were applied in SRTs of 10, 50 and 100 d during six months for wastewater treatment. Soluble microbial products (SMP) and extracellular polymeric substance (EPS) concentration analyses were conducted on the sludge of the bioreactors. Particle size distribution (PSD), Fourier-transform infrared (FTIR) spectroscopy, excitation- emission matrix (EEM) fluorescence spectroscopy, gel permission chromatography (GPC) were performed for determining the properties of the formed cake. Based on GPC test, at SRT of 10 d, organic compounds with varied molecular weights had the low concentration, while compounds with lower molecular weight were found more at SRTs of 50 and 100 d. FTIR and EEM analyses also revealed high concentration of protein compounds in MBR. Consequently, the membrane fouling was decreased in MBR at SRT of 10 d compared to SRTs of 50 and 100 d. In fact, transmembrane pressure (TMP) was 15, 21 and 25 kPa for SRTs of 10, 50 and 100 d, respectively. The EEM results showed that in addition to reduction of proteins by nano-adsorbent in SRTs of 10 and 50 d, the humic compounds were also reduced. The results showed the high efficiency of ZSM-5 nano-adsorbent for reducing of membrane fouling at the low SRT.
Danial Nayeri; Seyyed Alireza Mousavi; Azadeh Mehrabi
Abstract
In this study, oxytetracycline removal from aqueous solution by activated carbon prepared using corn stalks has been investigated. The adsorbent was characterized using Fourier transform infrared spectrophotometer (FTIR) and scanning electron microscope (SEM). The effects of main variables; adsorbent ...
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In this study, oxytetracycline removal from aqueous solution by activated carbon prepared using corn stalks has been investigated. The adsorbent was characterized using Fourier transform infrared spectrophotometer (FTIR) and scanning electron microscope (SEM). The effects of main variables; adsorbent dose, contact time, pH, and initial oxytetracycline concentration on the efficiency of adsorption efficiency were investigated. Results confirmed the effects of main variables and the maximum removal of antibiotic (99.9 %) achieved at initial concentration of 10 mg/L, pH of 9, and contact time of 60 min, when adsorbent dose was 1.5 g. The results of isotherm and kinetic studies showed that the oxytetracycline adsorption onto activated carbon prepared from corn stalks follows Freundlich isotherm (R2 = 0.98) and pseudo-second order kinetic model (R2 = 0.99). The maximum adsorption capacity of oxytetracycline was 522.6 mg/g. In brief, the activated carbon that has been prepared from corn stalks as low cost, non-toxic and environment friendly adsorbent shows a good ability for removal of oxytetracycline form water and wastewater.
Reza Jalilzadeh Yengejeh; Jafar Morshedi; Razieh Yazdizadeh
Volume 1, Issue 1 , March 2014, , Pages 23-27
Abstract
Pollution sources into the water, the necessity of qualitative studies of water resources is one of the most important new challenges for mankind in almost every parts of the world. Dissolved oxygen (DO) and Biochemical Oxygen Demand (BOD) are among parameters of water quality indexes which are considered ...
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Pollution sources into the water, the necessity of qualitative studies of water resources is one of the most important new challenges for mankind in almost every parts of the world. Dissolved oxygen (DO) and Biochemical Oxygen Demand (BOD) are among parameters of water quality indexes which are considered as water pollution indexes. In the present research, DO and BOD of Dez River basin water (in Dezful City) were studied and zoned by applying the Geographic Information System (GIS). Nine stations were considered for sampling during six months in 2013. The results indicate that the average maximum amount of DO at an average of six months is 8.47 mg/l in S1 station and the minimum amount is 1.71 mg/l in S8 station. The average maximum and minimum amounts for BOD during an average of six months are orderly 150.83 mg/l in S8 and 3.16 mg/l in S1. By a qualitative zoning, places that are prone to pollution can be recognized and measures can be taken for monitoring and preserving such areas. Decreasing the amount of water pollution and controlling the pollution sources are possible by adoption appropriate measures.
