Equilibrium and kinetics studies of Direct blue 71 adsorption from aqueous solutions using modified zeolite

This study deals with the application of Iranian zeolite as a low cost adsorbent for the removal of the Direct blue 71 (DB 71) from colored solution. Important parameters including equilibrium and contact time, initial dye concentration, effect of pH, and zeolite dosage were evaluated. Maximum dye removal was obtained at about 99.8% for 25 mg/L at 120 min of equilibrium. Higher adsorption efficiency of direct dye was obtained at higher dose and acidic pH. To analyze the adsorption equilibrium and kinetic, Langmuir, Freundlich, and Temkin isotherms as well as four kinetic models encompassing pseudo first-order, pseudo second-order, intraparticle diffusion, and Elovich were evaluated. The Langmuir isotherm (R2 = 0.995) and pseudo second-order models, gave the best fit to equilibrium experimental data. In Langmuir analysis, the maximum adsorption capacity (qm) by 13.66 mg/g was determined. Finally, the characteristics of zeolite including both natural and modified, such as compositions, surface morphology by X-ray diffraction technique (XRD), X-ray fluorescence (XRF), and scanning electron microscopy (SEM) were obtained. According to XRF analysis, it was demonstrated that Al2O3 and SiO2 are the most part of natural and modified zeolite. Furthermore, the clinoptilolite was determined as the significant crystalloid phase by XRD pattern

Catalytic Ozonation of Phenolic Wastewater: Identification and Toxicity of Intermediates

A new strategy in catalytic ozonation removal method for degradation and detoxification of phenol from industrial wastewater was investigated. Magnetic carbon nanocomposite, as a novel catalyst, was synthesized and then used in the catalytic ozonation process (COP) and the effects of operational conditions such as initial pH, reaction time, and initial concentration of phenol on the degradation efficiency and the toxicity assay have been investigated. The results showed that the highest catalytic potential was achieved at optimal neutral pH and the removal efficiency of phenol and COD is 98.5% and 69.8%, respectively. First-order modeling demonstrated that the reactions were dependent on the initial concentration of phenol, with kinetic constants varying from 0.038 min−1 ([phenol]o = 1500mg/L) to 1.273 min−1 ([phenol]o = 50mg/L). Bioassay analysis showed that phenol was highly toxic to Daphnia magna (LC50 96 h = 5.6mg/L). Comparison of toxicity units (TU) of row wastewater (36.01) and the treated effluent showed that TU value, after slightly increasing in the first steps of ozonation for construction of more toxic intermediates, severely reduced at the end of reaction (2.23).Thus, COP was able to effectively remove the toxicity of intermediates which were formed during the chemical oxidation of phenolic wastewaters

Degradation and toxicity reduction of phenol by ultrasound waves

The effects of parameters such as pH, kinetic constants and initial phenol concentration on the sonochemical degradation of phenol and toxicity assay were studied. The experimental results showed that lower pH and lower concentration of phenol favor the phenol degradation. But the rates of phenol degradation under sonication have always been quite low. It is found that the rate of ultrasonic degradation of phenol for initial concentration of 1 mg/L is 0.018 min-1 but later it reduces with increasing of phenol initial concentration substantially and the experimental data fitted well with pseudo first-order reaction rate equation. Bioassay tests showed that phenol was toxic to Daphnia magna and so resulted in quite low LC50 values. Comparison of toxicity units (TU) between phenol and effluent toxicity showed that the TU value for effluent was 1.21 times lower than that obtained for phenol solely. Thus, the toxicity of metabolites formed during the degradation of phenol is lower than the toxicity of phenol itself. KEY WORDS: Phenol, Ultrasound, Sonochemistry, Toxicity assay  Bull. Chem. Soc. Ethiop. 2007, 21(1), 33-38

Evaluation of dairy industry wastewater treatment and simultaneous bioelectricity generation in a catalyst-less and mediator-less membrane microbial fuel cell

Increased human activity and consumption of natural energy resources have led to decline in fossil fuel. These current methods of energy production are not compatible with the environment. In this study catalyst-less and mediator-less membrane microbial fuel cell (CAML-MMFC) represents a new method for simultaneous dairy industry wastewater treatment and bioelectricity generation. The CAML-MMFC used was designed as two chambered that included an anaerobic anode and aerobic cathode compartment and was separated from each other by a proton exchange membrane. The anode and cathode electrodes were made from graphite plate. Current intensity, power density and voltage produced from wastewater as fuel were measured and the effluent from the anode compartment was examined to evaluate pollutant decrease. The maximum current intensity and power density produced were respectively 3.74 mA and 621.13 mW/m2 on the anode surface, at OLR equal to 53.22 kgCOD/m3 d and at the external resistance of 1 k Ω. The maximum voltage produced was 0.856 V at OLR equal to 53.22 kgCOD/m3 d and at temperature 35oC. The maximum coulombic efficiency of 37.16 was achieved at OLR equal to 17.74 kgCOD/m3 d. The HRT was examined as a factor influencing the power generation and when it was 5 day, maximum voltage and power density were obtained. The maximum removal efficiency of COD, BOD5, NH3, NH4 +, dissolved phosphorus, phosphorus in suspended solids, SO4 2-, TSS, and VSS was respectively achieved at 90.46, 81.72, 73.22, 69.43, 31.18, 72.45, 39.43, 70.17 and 64.6. The results showed that generating bioelectricity and dairy industry wastewater treatment by CAML-MMFC are a good alternative for producing energy and treating wastewater at the same time. © 2014 King Saud University. Production and hosting by Elsevier B.V

Comparison of polyaluminum silicate chloride and electrocoagulation process, in natural organic matter removal from surface water in ghochan, Iran

Removal of Natural Organic Matter (NOM)is one of the most important objectives of water treatment plants but reducing these pollutants either present in water as dissolved or suspended form is not as efficient as is required in conventional treatment plants. The purpose of this study was comparison performance of composite polyaluminum silicate chloride (PASiC) and electrocoagulation (EC) process by aluminum electrodes in NOM removal from raw surface water.Удаление природных органических веществ (ПОВ) является одной из наиболее важных задач при очистке поверхностных вод. Однако удаление ПОВ, находящихся в растворенной форме или в виде суспензий, не настолько эффективно, как это требуется при работе водоочистных сооружений. Изучено влияние мутности, общего органического углерода (ООУ), адсорбции ПОВ при длине волны 254 нм (УФ254 нм), ХПК, щелочности в процессе электрокоагуляции и при использовании композитного четыреххлористого кремния полиалюминия (КЧКП).Видалення природних органічних речовин (ПОР) є одним з найбільш важливих завдань при очищенні поверхневих вод. Проте видалення ПОР, що знаходяться в розчиненій формі або у вигляді суспензій, не настільки ефективно, як це потрібно при роботі водоочисних споруд. Вивчений вплив каламутності, загального органічного вуглецю (ЗОУ), адсорбції ПОР при довжині хвилі 254 нм (УФ254 нм), ХПК, лужності в процесі електрокоагуляції і при використанні композитного чотирьоххлорістого кремнію поліалюмінію (КЧКП)

Fish and shrimp waste management at household and market in Bushehr, Iran

Abstract: The aim of this study was to investigate the estimation and management of fish and shrimp wastes in Bushehr province. Two-part questionnaire including the demographic information, and fish and shrimp waste disposal method were completed for 91 stores and 636 households. The quantity of generated wastes was estimated based on the 3 different Scenarios. In addition, the waste generation factor were calculated for common fish and shrimp species. Results showed the waste generation factor for fish and shrimp equal to 32.67 and 42%, respectively. The total quantity of fish- and shrimp-generated wastes in Bushehr province was estimated to be 29,388 tons per year, of which the quantity of generated waste by stores and by households was 3731 tons per year (16 ton per capita per year) and 8804 tons per year (34 kg per capita per year), respectively. The remaining quantity is related to other unaccounted sectors such as fish industries. Moreover, the biogas production potential from an anaerobic digestion were estimated 2,675,400 m3 per year, which is equivalent to 16,052 MWh. In addition, the biodiesel production potential was obtained equivalent to 19 kt, which is about 4.2% of the total diesel fuel requirement of the province in 2016. Graphic abstract: [Figure not available: see fulltext.

Estimation of landfill gas generation in a municipal solid waste disposal site by LandGEM mathematical model

Anaerobic decomposition of organic compounds in landfills is responsible for generation of greenhouse gases. The present study aimed to determine the total gas and methane emission from a landfill located in Hamedan (west of Iran) from 2011 to 2030. LandGEM 3.02 model was used to estimate the gas emission with the volumetric methane percent of 60%, production potential of 107, and methane generation rate of 0.2. Spatial distribution of annual methane and total landfill gas emission rate in the study area at three decades were provided through ArcGIS software. The results showed that organic and food wastes had the maximum amounts in the solid waste stream (over 75%). The results showed that 4.371×108 m3 methane would be produced after 20 years, mostly (4.053×106m3) in the first year. In addition, methane production capacity in Hamedan landfill site was 107 m3/Mg. According to the results, the maximum and minimum gas generation rates are in summer (the hottest season) and winter (the coldest season) respectively. The results of the LandGEM model represented that the total gas and methane generation rates will be significant in the first 10 years. The potential of rapidly degradable organic compounds for gas emission will be higher than that of slowly degradable organic compounds. The results obtained in the present study can be beneficially used in planning for energy production and other applications in landfill sites

Landfill site selection using a hybrid system of AHP-Fuzzy in GIS environment: A case study in Shiraz city, Iran

Landfilling with simplicity and economic advantages is the most common element for waste management in both developed and developing countries. Landfill site selection in a proper way is an important municipal planning process which prevent environmental issues including water pollution imposed for insanitary landfills. The present research was developed to exhibit a simplified method of multi criteria decision making (MCDM) and Fuzzy memberships in GIS environment to ascertain best landfill sites for Shiraz county, located south of Iran. 15 most common sub-criteria, documented in literature and implicated by Iranian environmental protection organization (IEPO) including surface water, ground water, land use, distance to well, soil type, slope, protected area, fault in environmental group, residential area, road, airport, village, infrastructure, historical area, wind direction in socio-economical group were selected and the weight of each criterion was determined based on expert's knowledge with use of analytical hierarchy process (AHP). The results of the present research are as follows: � Distance to residential area and groundwaters with weight of 0.36 and 0.28 were recognized as the most important criteria for landfill site selection. � The six suitable areas for landfill in Shiraz county is 1.003 of total area equal to 8710 ha. � AHP and Fuzzy memberships has a great potential and ability for landfill site selection. © 2019 The Author(s

Performance evaluation of enhanced SBR in simultaneous removal of nitrogen and phosphorous

BACKGROUND: Simultaneous nitrogen, phosphorous and COD removal in a pilot-scale enhanced Sequencing Batch Reactor (eSBR) was investigated. METHODS: The reactor consisted of a pre-anoxic zone and internal recycle and was fed with synthetic wastewater. The study was performed by operating the reactor in 6-hour cycles in three different operational modes during a time frame of 279 days. RESULTS: Under the best operational conditions, the average removal rate of COD, TN, and TP were obtained as 93.52, 88.31, and 97.56%, respectively. CONCLUSIONS: A significant denitrifying phosphorus removal (more than 80%) occurred at run1 and 3 which started the cycle under anoxic condition

Tinidazol antibiotic degradation in aqueous solution by zero valent iron nanoparticles and hydrogen peroxide in the presence of ultrasound radiation

The purpose of this study was to investigate the efficiency removal of the antibiotic Tinidazol by hybrid system of ultrasonic/nZVI/H₂O₂ (US/nZVI/H₂O₂) in aquatic environment. It examined the effect of variables such as concentration of antibiotic, nZVI and H₂O₂, frequency of US and pH. Also the performance of system in removal of COD and electrical energy consumed by the ultrasonic bath was investigated. Findings showed the best efficiency (93 %) for system in pH 3, concentration hydrogen peroxide of 1M, amount of 0,2 g of zero valent iron nanoparticles and 130 kHz radiation frequency. According to the results US/nZVI/H₂O₂ method can be good performance in removal of antibiotics Tinidazol and similar pollutants