On the crucial influence of some supporting electrolytes during electrocoagulation in the presence of aluminum electrodes

The influence of some supporting electrolytes on aluminum electrode oxidation and pH variation during electrocoagulation of an unskimmed milk sample and a cutting oil emulsion has been investigated. Among the electrolytes studied, sulfate anions were found to be quite harmful both for electrical consumption and electrocoagulation efficiency. At the opposite, chloride and ammonium ionswere particularly benefic respectively for aluminum corrosion and pH regulation, whereas sodium cations were observed to have a neutral role. The results indicate that electrocoagulation can be realized at lowanodic potential even in the presence of sulfate ions when the [Cl−]/[SO4 2−] ratio is around or greater than 1/10. The detrimental effect of sulfates on electrocoagulation efficiency can be thwarted by the use of the ammonium salt thanks to its related buffer effect

Teknologi emisi rendah: aplikasi aliran berpusar

Buku ini secara amnya menerangkan mengenai penggunaan teknologi pusaran udara untuk mengurangkan pembentukan emisi dari proses pembakaran seperti oksida nitrogen (NOx), karbon monoksida (CO) dan hidrokarbon tak terbakar (HC). Perbincangan dalam buku ini memfokuskan kemampuan pemusar udara aliran jejarian dengan pemboleh ubah kekuatan pusaran yang berupaya menambahbaik percampuran bahan api cecair dan udara serta mengawal pembentukan bahan cemar ketika dioperasikan pada tekanan ambien. Buku ini dipersembahkan dalam cara yang dirasakan dapat membantu pembaca untuk memahami masalah yang ditimbulkan dan bagaimana penggunaan teknologi pusaran dapat menyelesaikan masalah tersebut. Perlaksanaan penyelesaian yang dibincangkan merupakan gabungan daripada permodelan berkomputer serta ujikaji yang telah dijalankan di makmal. Permodelan berkomputer melibatkan analisis isoterma dan permodelan tindak balas (pembakaran) sementara keputusan ujikaji memberi lebih tumpuan kepada analisis emisi pembakaran. Walaupun tidak dinafikan terdapat pelbagai lagi kaedah yang dapat mengurangkan emisi, penulis merasakan teknologi pusaran yang dibentangkan dalam buku ini merupakan antara kaedah yang paling cekap dan mudah untuk dipraktikan dalam menghasilkan sebuah pembakar yang lebih mesra alam sekitar

A structural model for mitigation measures of critical cost overrun factors in highway projects in sindh province

Construction industry plays a major role in improving the socio-economic growth of any country. However, this industry is facing a serious problem of cost overrun globally and particular in Pakistan. Rapid growth in the construction sector in Pakistan has been observed along with many challenges, especially in highway projects. The most critical issues in highway projects are the cost overrun and lack of their mitigation measures. Hence, the objective of this research is to determine the critical factors of cost overrun, its significant mitigation measures and to develop a structural model of significant mitigation measures for critical cost overrun factors. The preliminary survey helped in identifying the critical factors of cost overrun in highway projects. In total, 64 common factors for cost overrun were identified from the literature review. Based on the common factors, a questionnaire was designed and distributed among the 30 selected experts to determine the critical factors of cost overrun. Out of 64 common factors, 24 were reported critical. The pilot study was carried out by developing a semi-structured questionnaire which was distributed among the same 30 construction experts for the purpose of determining the mitigation measures, which resulted in 113 measures. These mitigation measures along with the relevant 24 factors helped in the development of the final questionnaire to further narrow down the significant measures. This finalized questionnaire was distributed among 350 construction experts of highway projects to identify the significant mitigation measures for critical factors of cost overrun. The collected data was further used to develop a structural model for mitigation measures of critical factors of cost overrun by Smart PLS. Performance of the model has moderate explaining power as the predictive relevancy value is greater than 0.13. Significant mitigation measures of these critical factors were determined from the power loading of mitigations measures. This research would be helpful for construction managers in mitigating the relative risk to the project. Thus, it will directly benefit the construction community and contribute in raising the economy of the country

Long-term electrode behavior during treatment of arsenic contaminated groundwater by a pilot-scale iron electrocoagulation system.

Iron electrocoagulation (Fe-EC) is an effective technology to remove arsenic (As) from groundwater used for drinking. A commonly noted limitation of Fe-EC is fouling or passivation of electrode surfaces via rust accumulation over long-term use. In this study, we examined the effect of removing electrode surface layers on the performance of a large-scale (10,000 L/d capacity) Fe-EC plant in West Bengal, India. We also characterized the layers formed on the electrodes in active use for over 2 years at this plant. The electrode surfaces developed three distinct horizontal sections of layers that consisted of different minerals: calcite, Fe(III) precipitates and magnetite near the top, magnetite in the middle, and Fe(III) precipitates and magnetite near the bottom. The interior of all surface layers adjacent to the Fe(0) metal was dominated by magnetite. We determined the impact of surface layer removal by mechanical abrasion on Fe-EC performance by measuring solution composition (As, Fe, P, Si, Mn, Ca, pH, DO) and electrochemical parameters (total cell voltage and electrode interface potentials) during electrolysis. After electrode cleaning, the Fe concentration in the bulk solution increased substantially from 15.2 to 41.5 mg/L. This higher Fe concentration led to increased removal of a number of solutes. For As, the concentration reached below the 10 μg/L WHO MCL more rapidly and with less total Fe consumed (i.e. less electrical energy) after cleaning (128.4 μg/L As removed per kWh) compared to before cleaning (72.9 μg/L As removed per kWh). Similarly, the removal of P and Si improved after cleaning by 0.3 mg/L/kWh and 1.1 mg/L/kWh, respectively. Our results show that mechanically removing the surface layers that accumulate on electrodes over extended periods of Fe-EC operation can restore Fe-EC system efficiency (concentration of solute removed/kWh delivered). Since Fe release into the bulk solution substantially increased upon electrode cleaning, our results also suggest that routine electrode maintenance can ensure robust and reliable Fe-EC performance over year-long timescales

Electrochemical Process for Diazinon Removal from Aqueous Media: Design of Experiments, Optimization, and DLLME-GC-FID Method for Diazinon Determination

In the present study, electrochemical process was studied via removal of diazinon (O,O-diethyl O-2-isopropyl-6-methylpyrimidin-4-yl phosphorothioate) as an insecticide/ acaricide organic case study. Influences of three operational parameters including initial ferrous ion concentration, initial hydrogen peroxide concentration, and initial diazinon concentration were measured and optimized in diazinon removal process. Response surface methodology (RSM) was used to design the experiments. The experimental data collected in a laboratory-scaled batch reactor equipped with four graphite bar electrodes as cathode and an aluminum sheet electrode as an anode. Quantitative analysis of diazinon was done with gas chromatography equipped with flame photometric detector. Disperse liquid–liquid microextraction was used prior to gas chromatography in order to extraction and preconcentration of diazinon from aqueous media to extraction phase. Acetone and chlorobenzene were used as disperser and extraction solvent, respectively. Maximum diazinon removal efficiency of 87% (0.85mg mass removal) in C0 of 2mg/L and 80% (120mg mass removal) in C0 of 300mg/L was achieved under different experimental conditions. The obtained experimental data were used for model building by RSM approach. Finally, optimization process was carried out using RSM algorithm. © 2015, King Fahd University of Petroleum & Minerals

Implementing precision agriculture in the oil palm industry: a case of oil palm management system (OPAMS)

Sustainable agriculture slowly replaces the conventional agriculture practice as due to the need of having sustainable agriculture management to address mainly food scarcity issue over the world; and at a micro-level it’s advancement of technological means in order to adapt to the macro environment changes. The need of drastic changes in the global food system in order to achieve a more sustainable agriculture is inevitable. Agriculture industry stakeholders, especially those in oil palm industry, reckon the significance of pursuing sustainability due the competitiveness in the industry. Moreover, rigorous requirements which imposed by sustainable organizations and authorities has given rise to the industry stakeholders for continually seeking for better solutions to minimize the total operating cost. Yet even though these scenarios are what satisfies and act as the market drive to promote the research in precision technologies, the practices of precision technologies in Malaysia’s oil palm industries still lack in its pace. This research aims to develop a sustainable precision agriculture management system for the oil palm industry. Through semi-structured interview session, industry stakeholders revealed their perceptions on precision agriculture technologies. They also shared their experiences and obstacles they encountered during the implementation of precision agriculture technologies in their organization. The research then moved forward to the development of Oil Palm Management System (OPAMS) which serves as a monitoring and data management system to justify the decision making in oil palm plantation operational process to achieve sustainable goal. The system assists them in monitoring, control and properly manages their resources, including fertilizers, chemical, pesticides, energy and water with better efficiency. The research raised the awareness of precision agriculture practices in oil palm industry, allow industry stakeholders taking sustainability into account while making operating investment and management decisions

Removal of Trace Metal Contaminants from Potable Water by Electrocoagulation

This study investigated the effects of four operational and environmental variables on the removal of trace metal contaminants from drinking water by electrocoagulation (EC). Removal efficiencies for five metals (arsenic, cadmium, chromium, lead and nickel) were compared under varying combinations of electrode material, post-treatment, water composition and pH. Iron electrodes out-performed aluminum electrodes in removing chromium and arsenic. At pH 6.5, aluminum electrodes were slightly more effective at removing nickel and cadmium, while at pH 8.5, iron electrodes were more effective for these metals. Regardless of electrode, cadmium and nickel removal efficiencies were higher at pH 8.5 than at pH 6.5. Post-EC treatment using membrane filtration (0.45 μm) enhanced contaminant removal for all metals but nickel. With the exception of lead, all metals exhibited poorer removal efficiencies as the ionic strength of the background electrolyte increased, particularly in the very high-solids synthetic groundwaters. Residual aluminum concentrations were lowest at pH 6.5, while iron residuals were lowest in low ionic strength waters. Both aluminum and iron residuals required post-treatment filtration to meet drinking water standards. EC with post-treatment filtration appears to effectively remove trace metal contaminants to potable water standards, but both reactor and source water parameters critically impact removal efficiency

Radionuclides proportion and radiological risk assessment of soil samples collected in Covenant University, Ota, Ogun State Nigeria

The activity levels of 238U, 232Th and 40K in soil surrounding major office complexes in Covenant University were analyzed for radiological hazards to determine the safety of the residents in such environment. Sixteen (16) soil samples were collected, prepared and sent to Acme laboratory in Canada for analysis with the use of high purity germanium detector. The mean activity concentrations of 238U, 232Th and 40K were found to be 45?±?10, 135?±?8 and 195?±?20 respectively. The concentrations of 238U and 232Th were found to be higher than the world recommended standard of 35 and 30, while the result for 40K was noted to be lower than the world safe limit. The average values of Raeq, D, AED, Iyr, Hex and ELCR in this study were estimated to be 252.33?Bq/kg, 110.15 nGy/h, 0.13 mSv/y, 1.78, 0.68 and 0.47?×?10-3 respectively. It was noticed that none of the measured parameters was higher than the internationally recommended safe limits. 232Th was found to be the major contributor to the environmental radionuclides in the area of study. Therefore, the inhabitants of the office complexes whose environment was assessed are considered not be exposed to any radiological hazards

Defluoridation of drinking water by electrocoagulation/electroflotation in a stirred tank reactor with a comparative performance to an external-loop airlift reactor

Defluoridation using batch electrocoagulation/electroflotation (EC/EF) was carried out in two reactors for comparison purpose: a stirred tank reactor (STR) close to a conventional EC cell and an external-loop airlift reactor (ELAR) that was recently described as an innovative reactor for EC. The respective influences of current density, initial concentration and initial pH on the efficiency of defluoridation were investigated. The same trends were observed in both reactors, but the efficiency was higher in the STR at the beginning of the electrolysis, whereas similar values were usually achieved after 15 min operation. The influence of the initial pH was explained using the analyses of sludge composition and residual soluble aluminum species in the effluents, and it was related to the prevailing mechanisms of defluoridation. Fluoride removal and sludge reduction were both favored by an initial pH around 4, but this value required an additional pre-treatment for pH adjustment. Finally, electric energy consumption was similar in both reactors when current density was lower than 12 mA/cm2, but mixing and complete flotation of the pollutants were achieved without additional mechanical power in the ELAR, using only the overall liquid recirculation induced by H2 microbubbles generated by water electrolysis, which makes subsequent treatments easier to carry out

Rapid and Efficient Arsenic Removal by Iron Electrocoagulation Enabled with in Situ Generation of Hydrogen Peroxide.

Millions of people are exposed to toxic levels of dissolved arsenic in groundwater used for drinking. Iron electrocoagulation (FeEC) has been demonstrated as an effective technology to remove arsenic at an affordable price. However, FeEC requires long operating times (∼hours) to remove dissolved arsenic due to inherent kinetics limitations. Air cathode Assisted Iron Electrocoagulation (ACAIE) overcomes this limitation by cathodically generating H2O2 in situ. In ACAIE operation, rapid oxidation of Fe(II) and complete oxidation and removal of As(III) are achieved. We compare FeEC and ACAIE for removing As(III) from an initial concentration of 1464 μg/L, aiming for a final concentration of less than 4 μg/L. We demonstrate that at short electrolysis times (0.5 min), i.e., high charge dosage rates (1200 C/L/min), ACAIE consistently outperformed FeEC in bringing arsenic levels to less than WHO-MCL of 10 μg/L. Using XRD and XAS data, we conclusively show that poor arsenic removal in FeEC arises from incomplete As(III) oxidation, ineffective Fe(II) oxidation and the formation of Fe(II-III) (hydr)oxides at short electrolysis times (<20 min). Finally, we report successful ACAIE performance (retention time 19 s) in removing dissolved arsenic from contaminated groundwater in rural California