Abstract
In this study, the influence of different IEMs (ion exchange membranes) to performance of the hypochlorite electrolysis unit with Cl2 recovery stream was investigated. More specifically, Nafion 117—a representative cation exchange membrane (CEM)—and aminated polypheylene oxide (APPO)—an anion exchange membrane (AEM)—were installed in the hypochlorite electrolysis unit, and the performance and the energy efficiency of the units were evaluated and compared. Regardless of whether CEM (Nafion 117) or AEM (APPO) was installed, the rate of hypochlorite generation was increased (by up to 24.3% and 22.2% for Nafion 117 and APPO, respectively) compared with the unit without an IEM. On the other hand, the power efficiency and the optimum operation condition of hypochlorite production units seem to depend on the conductivity and stability of the installed IEM. As the result, between Nafion 117 and APPO, higher performance and efficiency were achieved with Nafion 117, due to excellent conductivity and stability of the membrane.
Key Words
APPO; electrolysis; hypochlorite; ion exchange membrane; Nafion; virus removal
Address
Seong K. Kim, Dong-Min Shin and Ji Won Rhim: Department of Chemical Engineering, Hannam University, 1646 Yuseongdae-ro, Yuseong-gu, Daejeon, 34054, Republic of Korea
Abstract
Given the limited water resources and the presence of multiple decision makers with different and usually conflicting objectives in the exploitation of water resources systems, especially dam's reservoirs; therefore, the decision to determine the optimal allocation of reservoir water among decision-makers and stakeholders is a difficult task. In this study, by combining a fuzzy VIKOR technique or fuzzy multi-criteria decision making (FMCDM) and the Young's bilateral bargaining model, a new method was developed to determine the optimal quantitative and qualitative water allocation of dam's reservoir water with the aim of increasing the utility of decision makers and stakeholders and reducing the conflicts among them. In this study, by identifying the stakeholders involved in the exploitation of the dam reservoir and determining their utility, the optimal points on trade-off curve with quantitative and qualitative objectives presented by Mojarabi et al. (2019) were ranked based on the quantitative and qualitative criteria, and economic, social and environmental factors using the fuzzy VIKOR technique. In the proposed method, the weights of the criteria were determined by each decision maker using the entropy method. The results of a fuzzy decision-making method demonstrated that the Young's bilateral bargaining model was developed to determine the point agreed between the decisions makers on the trade-off curve. In the proposed method, (a) the opinions of decision makers and stakeholders were considered according to different criteria in the exploitation of the dam reservoir, (b) because the decision makers considered the different factors in addition to quantitative and qualitative criteria, they were willing to participate in bargaining and reconsider their ideals, (c) due to the use of a fuzzy-logic based decision-making approach and considering different criteria, the utility of all decision makers was close to each other and the scope of bargaining became smaller, leading to an increase in the possibility of reaching an agreement in a shorter time period using game theory and (d) all qualitative judgments without considering explicitness of the decision makers were applied to the model using the fuzzy logic. The results of using the proposed method for the optimal exploitation of Iran's 15-Khordad dam reservoir over a 30-year period (1968-1997) showed the possibility of the agreement on the water allocation of the monthly total dissolved solids (TDS)=1,490 mg⁄(L )considering the different factors based on the opinions of decision makers and reducing conflicts among them.
Key Words
bargaining model; fuzzy decision making; reservoir exploitation; water quality
Address
M.J. Shirangi, H. Babazadeh and A. Saremi: Department of Water Science and Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
E. Shirangi: Department of Civil Engineering, Karaj Branch, Islamic Azad University, Karaj, Iran
Abstract
As a result of algal bloom, algal organic matters (AOMs) are rapidly increased in surface water. AOMs can act as precursors for the formation of harmful disinfection by-products (DBPs), which are serious problems in water treatment and human health. The main aim of this study is to characterize the formation of DBPs from AOMs produced by three different algae such as Oscillatoria sp., Anabaena sp., and Microcystis aeruginosa under different algal growth phases. In an effort to examine formation of DBPs during chlorination, chloroform (TCM), dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) were determined under various CT (product of disinfectant concentration and contact time, mgmin/L) values. Generally, the amounts of DBPs tended to increase with increasing CT values at the most growth phases. However, there was a significant difference between the amounts of DBPs produced by the three algal species at different growth phases. This result is likely due to the chemical composition variability of AOM from different algae at different growth phases. In addition, the effect of pre-ozonation on coagulation for the removal of AOMs from three algal species was investigated. The pre-ozonation had a positive effect on the coagulation/flocculation of AOMs.
Key Words
algal organic matter(AOM); chlorination; disinfection by-products(DBPs); Pre-ozonation
Address
Jing Wang: Research and Development Department, CanFit Resource Technologies Inc.,65 Fushi-Ro, Haidian District, Beijing, China
Se-Hyun Oh and Yunchul Cho: Department of Civil and Environmental Engineering, Daejeon University, 62 Daehak-ro, Dong-gu, Daejeon 34520, Republic of Korea
Shadia R. Tewfik, Mohamed H. Sorour, Hayam F. Shaalan, Heba A. Hani, Abdelghani G. Abulnour, Marwa M. El Sayed, Yomna O. Mostafa and Mahmoud A. Eltoukhy
Abstract
Membrane separation is widely used for several applications such as water treatment, membrane reactors and climate change. Cross-linked organic-inorganic hybrid polyvinylidene fluoride (PVDF) / Tetraethyl orthosilicate (TEOS) was adopted for the preparation of optimized hollow membrane (HFM) for membrane distillation or other low pressure separators for mechanical properties and permeability under varying pretreatment schemes. HFMs were prepared on semi-pilot membrane fabrication system. Novel adopted post-treatment schemes involved soaking in glycerol, magnesium sulphate (MgSO4), sodium hypochlorite (NaOCl), and isopropanol for different durations. All fibers were characterized for morphology using a scanning electron microscope (SEM), surface roughness using atomic force microscope (AFM), elemental composition by examining Energy Dispersive Spectroscopy (EDS), water contact angle (CAo) and porosity. The performance of the fibers was evaluated for pure water permeation flux (PWF). Post-treatment with MgSO4 gave the highest both tensile modulus and flux. Assessment of properties and performance revealed comparable results with other organic-inorganic separators, HF or flat. In spite of few reported data on post treatment using MgSO4 in presence of TEOS, this proves the potential of low cost treatment without negative impact on other membrane properties. The flux is also comparable with hypochlorite which manifests substantial precaution requirements in actual industrial use.The relatively high values of flux/bar for sample treated with TEOS, post treated with MgSO4 and hypochlorite are 88 and 82 LMH/bar respectively.
Key Words
characterization; hollow fiber membranes; performance evaluation; post-treatment; PVDF; TEOS
Address
Shadia R. Tewfik, Mohamed H. Sorour, Hayam F. Shaalan, Heba A. Hani, Abdelghani G. Abulnour, Marwa M. El Sayed and Mahmoud A. Eltoukhy: Chemical Engineering and Pilot Plant Department, Engineering and Renewable Energy Research Institute, National Research Centre, El-Buhouth Street, Dokki, Giza, Egypt
Yomna O. Mostafa: Mechanical Engineering Department, Engineering and Renewable Energy Research Institute, National Research Centre, El-Buhouth Street, Dokki, Giza, Egypt
Abstract
In the developing country like India, groundwater is the main sources for household, irrigation and industrial use. Its contamination poses hydro-geological and environmental concern. The hazardous waste sites such as landfills can lead to contamination of ground water. The contaminants existing at such sites can eventually find ingress down through the soil and into the groundwater in case of leakage. It is necessary to understand the process of migration of pollutants through sub-surface porous medium for avoiding health risks. On this backdrop, the present paper investigates the behavior of pollutants' migration through porous media. The laboratory experiments were carried out on a soil-column model that represents porous media. Two different types of soils (standard sand and red soil) were considered as the media. Further, two different solutes, i.e., non-reactive and reactive, were used. The experimental results are simulated through numerical modeling. The percentage variation in the experimental and numerical results is found to be in the range of 0.75- 11.23 % and 0.84 – 1.26% in case of standard sand and red soil, respectively. While a close agreement is observed in most of the breakthrough curves obtained experimentally and numerically, good agreement is seen in either result in one case.
Key Words
break through curves (BTCs); continuous type boundary condition; finite element method (FEM); non- reactive solutes; pollutants' migration; pulse type boundary condition; reactive solute; soil- column; transport phenomena
Address
Smita Bhushan Patil: Department of Civil Engineering, Datta Meghe College of Engineering, Navi Mumbai-400708, India
Hemant Sharad Chore: Department of Civil Engineering, Dr. B. R. Ambedkar NIT Jalandhar-147027, India
Vishwas Abhimanyu Sawant: Department of Civil Engineering, Institute of Technology, Haridwar Road, Roorkee -247667, India
