Sharif Digital Repository

This article discusses the distribution of total petroleum hydrocarbons (TPH) contamination in soil within areas of the South Pars Gas Complex (S.P.G.C.), located on the northern shore of the Persian Gulf. To assess the potential risk to groundwater, in situ contaminant mobility was also examined in vertical soil profiles. Sampling was conducted in two rounds, and TPH was determined in accordance with standard methods of TPH analysis. The maximum detected concentration was 10268±785 mg/kg in the area of the waste disposal site. Significant heterogeneity in natural attenuation of different hydrocarbon compounds during transport in the soil was observed. Although the groundwater samples did... 

Low cost dispersed supported cobalt oxide nanocatalysts on activated carbon (AC) were prepared by two different methods: (1) combined impregnation and deposition–precipitation (IMP-DP) and (2) heterogeneous deposition–precipitation (HDP). XRD, TEM, FESEM, BET and Boehm techniques were used for the characterization of the support and the catalysts. Characterization analyses indicated the negative effect of the wet impregnation method on the IMP-DP technique for the preparation of catalysts for the total oxidation of cyclohexane in air. The catalysts prepared by HDP and IMP-DP methods were found to have significant differences in oxidation activity, morphology, particle size, and shape of... 

Copper and cobalt oxides supported on almond shell derived activated carbon (AC) with different loadings were synthesized by sequential and co-deposition-precipitation methods leading to Cu(shell)/Co(core)/AC, Co(shell)/Cu(core)/AC and Cu-Co(mixed)/AC catalysts that were subsequently used for catalytic oxidation of gaseous mixtures of toluene and cyclohexane in air in a tubular flow reactor. The catalysts and the support were characterized by Boehm test, Brunauer-Emmett-Teller (BET) surface area, X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy... 

In this paper, the effect of ozone on membrane fouling of membrane bioreactor (MBR) systems was investigated. Sludge specification such as soluble microbial product (SMP), extracellular polymeric substance (EPS), viscosity, particle size distribution (PSD), microscopic observations and sludge volume index (SVI) in presence of ozone were determined. Further, EPS, Fourier-transform infrared (FTIR) analysis, excitation-emission matrix (EEM) fluorescence spectroscopy, and gel permission chromatography (GPC) are considered to determine cake layer characteristics. The results indicated COD removal did not show significant difference with ozonation. Ozone also increases the particle size and... 

Produced water (PW), water extracted along with oil, can cause important environmental challenges due to its high volume and salinity and is considered a key factor in the economic exploitation of oil fields. Therefore, making use of a cost-effective integrated system of wastewater treatment is a fundamental requirement in oil and gas industries. In this paper, the integrated PW treatment system is presented using superstructure-based mathematical optimisation methodology which is aimed at minimising the total annual cost. Two distinct scenarios of injection and reuse in industrial scale are considered to propose an efficient and optimal integrated system. The results show that, despite the... 

In order to achieve a hydrogen economy, developing widespread hydrogen supply systems are vitally important. A large number of technological options exist and are still in development for hydrogen production, storage, distribution., which cause various pathways for supplying hydrogen. Besides the technical factors, there are other effective parameters such as cost, operability, reliability, environmental impacts, safety and social implications that should be considered when assessing the different pathways as optimal and viable long-term alternatives. To aid this decision-making process, we have developed a generic optimization-based model for the long-range energy planning and design of... 

A comprehensive representation of the environmental impact of a plant should incorporate not only the process variables that mainly affect the generation step but also the non-process ambient conditions that have influence on the dispersion step. Albeit, at best, only the process-related variables can be manipulated in order to optimize the environmental behavior of the process. In this study, an environmental model is coupled with a chemical process model. The approach is applied to an existing nitric acid production plant to study the effects of selected process variables on the environmental impact of the process. The insights that this approach provides can be used in retrofit studies to... 

The majority of environmental legislators advise pollution prevention (P2) for reducing the environmental impact of industrial activities. This approach calls for assessing different methods to reduce the final concentration of environmentally harmful species in process effluents; one method is source reduction, e.g. by modifying process conditions to hinder production of pollutants. There are methods for predicting (targeting) furnace CO2, NO(x) and SO(x) emissions in an industrial site indirectly and via the level of energy consumed in the process. However, no method exists for targeting process-related emissions when they are not related directly to energy use. In this paper, a method is... 

Stricter environmental regulations posed on chemical process industries (CPI), and the ever-increasing costs of end-of-pipe treatment, explain why chemical process industries have adopted new 'cleaner production' approaches in new designs and in retrofits. Finding environmentally clean alternatives for retrofitting existing processes has been addressed with various approaches. In this paper, a previous approach by the same authors is extended to include EHS criteria for targeting waste reduction in chemical processes, The method is applied to an existing local production facility as a case study and risk-based pollution prevention (P2) targets, and the appropriate direction and magnitude of... 

Finding environmentally clean alternatives for retrofitting existing processes has been addressed with various approaches. In this paper, a previous pollution prevention (P2) approach by the same authors is extended to include EHS criteria for targeting waste reduction in chemical processes. The method is applied to an existing facility as a case study and most viable modification are highlighted in order to improve the environmental conditions of the plant with the regulatory constraints in mind. The advantages of the present approach are that the proposed solutions are based on a precise, integrated description (simulated model) of the plant and the environment, practical feasibility of... 

Physical separation methods, especially membrane technology, can be a good substitute for biological wastewater treatment, due to its simple constructions and operations. There are many papers and patents in this field. Membranes need to be cleaned periodically to be able to operate economically, and need to be replaced after a while. Several factors can influence the membrane cleaning procedure, including pressure of backwash, acid and base concentration, duration of forward washing, and duration of acid-base backwashing. In this study the effect of these parameters was investigated to find an optimum condition which could result in a good polyethersulphone (PES) membrane cleaning with less... 

The present work deals with application of 25-2 fractional factorial design (FFD) to evaluate the operating parameters on starch separation from synthetic starchy wastewater using a hydrophilic polyethersulfone membrane with 0.65 μm pore size in a plate and frame handmade membrane module. The analysis of variance (ANOVA) combined with F-test was also used to recognize non-significant terms. The performance of the filtration process was evaluated by calculating the COD removal percentage (rejection factor) and permeate flux. In this experiment, five input parameters were surveyed, including trans membrane pressure (TMP), flow and temperature of feed, pH and concentration of wastewater. In... 

Chlorella vulgaris was cultivated in a hybrid (two-stage) system. The effect of the transferring time from nutrient-replete phase with a low light intensity (photobioreactor) to the nutrient deprivation phase (open pond) with a higher light intensity, as well as the effect of initial cell concentration in the deprivation phase, on the growth rate and lipid content of the microalgae was investigated. The microalgae were transferred to the nutrient deprived medium at different intervals with various initial cell concentrations. Transferring the cultivated medium of the 4th day with the initial cell concentration of 66 mg L−1 into the deprivation phase resulted in a highest lipid productivity... 

Background: Integrated sewage sludge handling and heavy metal management are important issues that scientists are working to solve today. Methods: Hydrothermal carbonization of dewatered digested sewage sludge (DDSS) under various conditions is carried out in this work, followed by alkali activation. The response surface methodology is used to investigate the operating process conditions and optimize them in order to produce hydrochar with the highest modified adsorption capacity (yield and Pb2+ adsorption). Significant Findings: The ideal conditions are 182.4°C, 4.9 hours, 5.025 (w/w) water/DDSS ratio, and 3.5 (w/w) ZnCl2/DDSS ratio. In addition, the Langmuir isotherm (qmax =109.3 mg/g) and... 

Monometallic and bimetallic supported metal oxides catalysts on γ-alumina were prepared by heterogeneous deposition-precipitation. The γ-alumina used as a support was synthesized by the sol-gel and the co-precipitation methods. Supports and catalysts were characterized by Brunauer–Emmett–Teller (BET) surface area, X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The performance of the prepared catalysts was studied for total oxidation of toluene in air at different relative humidity and oxidation temperatures. Efficiency of bimetallic catalysts for deep oxidation of toluene was... 

Today, sugarcane bagasse (SB) is used for bioethanol and biodiesel production, energy generation, and adsorbent synthesis. The goal of this project is to determine the optimized conditions for producing adsorbent from sugarcane bagasse using hydrothermal carbonization (HTC) and KOH activation. To optimize process parameters such as reaction temperature, residence time, ZnCl2/SB mixing ratios, and water/SB mixing ratios, response surface methodology was used. The results revealed that the optimum modified adsorption occurred at 180 °C, 11.5 h, a water to biomass ratio of (5:1), and a ZnCl2 to precursor ratio of (3.5:1). The physicochemical features of optimum activated hydrochar were... 

Recycling is one of the main ways of reducing the consumption of resources (reducing the exergy loss of systems). The economic indices (NPV, IRR, etc.) cannot be used to comprehensively assess the sustainability of the recycling process. For overcoming this challenge, the assessment function of “the saved exergoeconomic cost of production through recycling (ΔExC)“ was developed. For investing in line with sustainability, the high-priority flow for recycling must be distinguished from other flows in the system. Water Quality Pyramid (WQP) was presented based on the unit exergoeconomic cost index (c) to prioritize the flows in the system. The developed method was used to assess the... 

Water-energy nexus approach analyses water and energy interactions to provide sustainable usage of resources. This study incorporates a comprehensive bottom-up optimization model to assess the combination of technologies based on the water-energy nexus (watergy) optimal point. The watergy reference system is introduced according to six principles of the watergy system to achieve this goal. In this study, a new method is developed by adding an integration layer to the optimizing model with the minimum total cost objective function. In this layer, the demands for water and energy, for supplying the water and energy services, are calculated endogenously. A sensitivity analysis is performed by... 

Integrated biomass waste management and fresh water supply are crucial environmental problems that researchers are laboring to clarify today. The co-hydrothermal carbonization (co-HTC) of sugarcane bagasse (SB) and digested sewage sludge (DSS), with KOH activation, for SB and DSS waste management, was accomplished. In this research, the effect of process parameters and biomass ratio during co-HTC on modified hydrochar adsorption capacities was critically evaluated. To optimize operating parameters (temperature, time, catalyst/precursor ratio, water/precursor ratio, and SB/DSS ratio, response surface methodology was used. The optimum condition was 180 °C, 9.6 h, 3/1 DSS/SB ratio ([Formula... 

The pollution existence around Sarkhoun refinery and the way of its probable present existence were studied. Due to the lack of underground water in the area and the existence of hardpans near to soil surface, pollution spread through vapor and hydrocarbon condensations in vados zone. Hydrocarbon pollution mostly occurred in the north of refinery which means in the place of the evaporation basin of phase 1 and the old evaporation basin of phase 2 in that side a part of the pollution was observed in the east of the refinery, which was related to the tube lines breakage. However, it was expected the pollution to spread towards center and west parts of the refinery, but the investigations...