Semiha Arayici

Assessment of Biogas use as an Energy Source from Anaerobic Digestion of Brewery Wastewater

Energy recovery from a crossflow ultrafiltration (UF) membraneunit employed in order to improve the performance of an anaerobic contact digester for the treatment of brewery wastewater was assessed. The performance of the pilot-scale anaerobic UF membrane system was studied for over 15 months. At steady-state conditions, an organic loading rate of 28.5 kg COD m-3 d-1, a hydraulic retention time of 4.2 days and overall COD and BOD removal efficiencies of 99% and almost 100% were achieved, respectively. Percent methane in biogas was found to be in a range of 67–79% with the corresponding methane yield of 0.28–0.35 m3 CH4 kg-1 CODremoved. The potential energy recovery from the system treating brewery wastewater at an OLR of 28.5 kg COD m-3 d-1 was 87 MJ d-1 which would enable to maintain all energy requirements of the feed pump, mixing and heating of the reactor contents. In addition to this, 71% of the energy requirement for recirculating the reactor content through the membranes would also be recovered.

Comparison of Activated Carbon and Pyrolyzed Biomass for Removal of Humic Acid From Aqueous Solution

The pyrolysis of sewage sludge (SS) and olive mill waste (OMW) was carried out under nitrogen atmosphere and analyzed thermogravimetric and scanning electron microscopy micrographs. Removal capacity of pyrolyzed cokes was measured by humic acid solution. Humic substances can react with chlorine to produce carcinogens in drinking water. Activated carbon can be used as an effective treatment method to remove humic substances from water to prior to disinfection by chlorination. Olive mill waste, an agricultural byproduct and sewage sludge were used to produce acti- vated carbon by pyrolysis with the addition of zinc chloride to enhance the reaction. Activated carbon was also produced using olive mill waste and sewage sludge. Both of them were compared to a commercially-available activated carbon product. Optimum pyrolysis conditions and concentration of the activating agent were identified. The equilibrium parame- ter model of the Freundlich isotherm and Langmuir isotherm was applied to the adsorption data, and the efficiency of py- rolyzed coke was determined. Activated carbon produced from olive waste material had a lower specific surface area (437.92 m 2 /g) than activated carbon produced from sewage sludge (814.48 m 2 /g). While both of these were lower than the surface area of a commercially activated carbon, the latter fell within the expected range of commercial products, thus suggesting an effective means of producing activated carbon while reducing sewage waste disposal costs. Municipal and industrial plants in Turkey, and other countries, consume large volumes of water for various pur- poses. The water quality that is required for a plant varies with the specific purpose, and so the quality of water that is discharged from a plant. Increasing demands on existing water supplies place pressure on wastewater facilities to adequately treat and release large amounts of water. The quality of natural waters varies with source (e.g., groundwa- ter aquifer or surface water body), but all waters contain some minerals, trace elements and organic substances, and are treated to different levels of purity depending upon their intended use. Humic substances are abundant organic compounds found in sediment, soil and even in rocks that are formed from the decay of organic molecules from vegetation, ani- mals, and microbes. Not surprisingly, coal, which is formed when plant material is compressed under extreme pressure in a low-oxygen environment, can be high in humic substances. Water, flowing through coal seams, can accumulate and carry humic substances to groundwater sources and surface water bodies. The nature of these substances can vary widely, but in general they can be defined as acidic, hydro- philic and complex materials, including humic acids, fulvic acids and humins. Humic acids are common in natural wa- ters and pose no risk to humans or animals in their unaltered states.

An evaluation of tannery industry wastewater treatment sludge gasification by artificial neural network modeling.

This paper reports on the calorific value of synthetic gas (syngas) produced by gasification of dewatered sludge derived from treatment of tannery wastewater. Proximate and ultimate analyses of samples were performed. Thermochemical conversion alters the chemical structure of the waste. Dried air was used as a gasification agent at varying flow rates, which allowed the feedstock to be quickly converted into gas by means of different heterogeneous reactions. A lab-scale updraft fixed-bed steel reactor was used for thermochemical conversion of sludge samples. Artificial neural network (ANN) modeling techniques were used to observe variations in the syngas related to operational conditions. Modeled outputs showed that temporal changes of model predictions were in close accordance with real values. Correlation coefficients (r) showed that the ANN used in this study gave results with high sensitivity.

Adsorption of 17β-estradiol and estrone by activated carbon derived from sewage sludge

AbstractNowadays, the number of treatment plants has been increasing due to advancing technology and industrialization throughout Turkey and the world. This situation brings with it the need to analyse the features of the wastewater of treatment plants and treatment sludge in a more detailed way. In recent years, it has been remarkable to see studies conducted on endocrine disrupting substances (EDCs) in wastewaters and treatment sludge and the effects of these substances on the environment and public health. Being one of the estrogenic hormones, which are EDCs and which are found naturally in organisms, 17β-estradiol and estrone are highly important for the ecological balance. In the adsorption studies for the removal of estrogenic hormones, removal efficiencies, adsorption isotherms, kinetic values and thermodynamic studies have been conducted for 17β-estradiol and estrone. In adsorption studies, isotherm calculations are made with 90% and over removal efficiency and it is seen that the adsorption is in...

Thermal treatment of fleshing residue for producing syngas

In this paper, characteristics of syngas from the pyrolysis and gasification of tannery industry fleshing residues has been investigated. Pyrolysis and gasification behaviour were evaluated in terms of syngas composition and total energy production. Dried air and pure oxygen (99%) were used as gasification agents. Experiments were also performed in oxygen-free media. H2, CO and CH4 levels in producer gas were analysed and calorific values were calculated. Besides, weight and volume reductions during each experiment were reported. Dried air flow varied between 0.05 and 0.5 L/min during experiments. Syngas composition with higher calorific value was achieved between 0.1–0.2 L/min. It was determined that calorific values decreased related to the decrease in volume percentages of H2, CO and CH4 over 0.2 L/min gas flow. According to the statistical analysis, gasification agent had an important role in gasification performance. Average calorific value, achieved by pure oxygen, was higher than the value achieved by dried air. The lowest efficiency was achieved in oxygen-free media.

Equilibrium modeling of ph in environmental treatment processes

Abstract This work describes a novel approach to the theoretical prediction of optimal pH values of critical importance to the efficiency of a number of wastewater treatment processes such as precipitation, coprecipitation, coagulation, flocculation, adsorption, oxidation and reduction. The developed equlibrium pH modelling approach is comprised of selecting the appropriate representative cqulibrium data among other complex equlibria which is key to the prediction of the optimal pH under investigation, and subsequently solving the algebraic or differential hydrogen ion‐dependent equation resulting from this evaluation. This approach has been applied to environmental problems such as minimum solubility of boehmite, phosphate precipitation by ferric and aluminium salt flocculants, lime‐sulfide treatment of zinc ion containing wastewater. silver ion precipitation from photographic effluents, and isoelectric pH of hydrous ferric oxide in the absence and presence of chromate.

Wet Peroxidation of Olive Oil Mill Wastewater for Sludge Minimization

Advanced oxidation process treatment method has been adapted to olive oil mill wastewater (OMW) for treatability in conventional plants by the aim of sludge minimization. Lots of olive oil mills have facilities in the Aegean Region, Turkey. Wastewater, used in this study, was collected from these factories. Because of the advanced and expensive treatment methods of this wastewater, regulations and limitations are ignored. 95 °C temperature and 10 bar pressure conditions were used with H2O2 as an oxidant in wet oxidation method. Over 96% of oil-grease and 48% of chemical oxygen demand (COD) removal were achieved using wet air peroxidation in conditions with 2.5 mL H2O2/100 mL in 1 h. The influence of hydrogen peroxide with temperature and pressure makes the oil in wastewater soluble and in that way can be treatable in conventional plants.

Composition and energy potential of industrial sludge derived synthetic gas

The study focused on the synthetic gas formation and gasification efficiency of an industrial sludge. Optimum conditions for gasification were determined and content of synthetic gas was investigated. Gasification is a partial oxidation process whereby a carbon source such as coal, natural gas or biomass, is broken down into carbon monoxide and hydrogen, plus carbon dioxide and possibly hydrocarbon molecules such as methane. It is reported that during the gasification process, all of the useful molecules which produce energy when burned are separated from the unwanted parts of the organic matter such as soot, tar, and ash. Therefore, this process is much cleaner than combustion process. Gasification studies over 700°C produced a synthetic gas that involved 20%-30% CO, 30%-40% H2 and 5%-15% CH4 by volume. Calorific values of 2000 kcal/m3 in average and maximum 3000 kcal/m3 were achieved by gasification both with dried air and pure oxygen as gasification agents.

Coal pyrolysis and coal briquetting for production of smokeless fuel

Abstract To investigate the possibility of direct production of smokeless fuel, a moderate temperature coking was applied. Coals used for this purposes are named as No:800 in International Classification and cause considerable amounts of smoke emissions due to their high tar contents, when burned. Following a preheating treatment at 120° C, the smokeless fuels (semicokes) were produced by coking of the samples 16–32 mm at 450° C, with a heating rate of 150° C/h. These semicokes have been found to be strong, their tar contents are far below 2%, and volatile matters are mainly composed of CH4 and H2. The formation of semicoke particles smaller than 10 mm at the level of 25 to 30%, could not be avoided. Briquettes prepared by using these particles and tar or molasses as binder, were also found suitable for heating purposes.