International Journal of Environmental Engineering (9 papers in press)
Removal of Cyanide and copper simultaneously from cyanide barren solution
by Yali Zhang, Jing Yang, Xiaogen Tian
Abstract: cyanide barren solution in gold companies cannot be discharged directly. A new method was used to remove cyanide and copper, and good results have been achieved. A SiO2-TiO2 Nanocomposites material has been prepared, which has a higher specific surface area and larger pore volume. It can remove cyanide and copper simultaneously by adsorption and photocatalytic oxidation. The effects of variables such as time, pH and initial concentration were also studied. The removal rates of cyanide and copper can reach 85% and 90%, respectively, under the following conditions: 0.05g adsorbents for 20ml cyanide barren solution, 10 of the pH value, 2h of adsorption and 1h of photodegradation time.
Keywords: SiO2-TiO2 Nanocomposites; cyanide barren solution; adsorption; photodegradation.
Formation, properties and revegetation prospects for bauxite processing residue and the effects of seawater neutralization
by Yaying Li, Richard Haynes
Abstract: For every tonne of alumina extracted from bauxite ore by the Bayer process (dissolution of Al-containing minerals in hot NaOH), 1-2 tonnes of alkaline, saline/sodic bauxite processing residue is produced. Partial neutralization of this residue prior to its deposition in land-based lagoons or impoundments minimizes the need to treat the alkaline, sodic drainage from the impoundments both during operation and following closure of the alumina refinery. For refineries close to the marine environment, seawater neutralization is a convenient technique. Some of the Na is replaced by Mg, Ca and K present in the seawater and reactive, soluble alkalinity is converted to poorly soluble alkaline solids (Mg and Ca hydroxides and hydroxycarbonates) with the result that the pH is reduced from 10-13 down to 8.5-9.5. Nevertheless, as yet, there are no reports of revegetation of the neutralized material. Growth limiting factors are likely to include alkalinity, sodicity, salinity, nutrient deficiencies and poor soil physical conditions. There are a number of questions related to revegetation of neutralized residue mud that need to be resolved including the extent to which the pH rises during storage (due to dissolution of residual solid phase alkalinity), the degree to which physical properties of mud are modified by neutralization (and agglomeration of mud particles), the severity of the key constraints to plant growth and therefore the potential need for addition of amendments (e.g. gypsum) and the role of added organic matter (e.g. biosolids, compost etc) and soil fauna (e.g. earthworms) in improving physical conditions for plant growth. Future research needs to address these issues.
Keywords: bauxite residue; red mud; revegetation; Bayer process; seawater neutralization.
ASSESSMENT OF WATER QUALITY PARAMETERS OF BHALSWA LAKE IN NEW DELHI
by Deepika Singh, S.K. Singh
Abstract: Bhalswa Lake in New Delhi is one of the important lakes which are being severely degraded because of the effluent/sewage coming from nearby Dairy and Residential Area. In this study, some physiochemical characteristics of Bhalswa lake were investigated. Physical parameters such as, electrical conductivity (EC), Salinity, total suspended solid (TSS), total dissolved solids (TDS), and chemical parameters such as pH, alkalinity, hardness, chloride, sulphate, nitrate, phosphate, dissolved oxygen(DO), chemical oxygen demand(COD), biochemical oxygen demand(BOD), sodium, potassium and calcium were examined. Results of the study indicated that lake water is highly contaminated and not suitable for recreational activities as it contains high amount of organic matter, high algal growth, slightly high pH, BOD is high as compare to given standards by CPCB for outdoor bathing. The study discusses the water quality of Bhalswa Lake and comprises the water quality with given standards.
Keywords: Bhalswa Lake; Physico-chemical Parameter; Sampling; Recreational Activities; SAR; RSC.
Optimization of coagulation (Poly Iron chloride) process for partially stabilized leachate using response surface methodology (RSM)
by Nur Shaylinda Mohd Zin, Hamidi Abdul Aziz, Mohd Nordin Adlan, Azlan Ariffin, Irvan Dahlan
Abstract: A coagulation and flocculation treatment method was applied on partially stabilized leachate of Matang Landfill. The interactions and effects of dose and pH on the removal of SS (suspended solid), color and chemical oxygen demand (COD) were investigated, analysed and optimized through RSM. The optimal condition obtained from the satisfactory mathematical model was 0.24 g/L Fe and 4.94 of poly iron chloride (PHI) dose and pH, respectively. Confirmatory experiment indicates good agreement between model prediction and experimental value. Therefore, RSM is an appropriate statistical tool in the optimization of PHI coagulation and flocculation process.
Keywords: prehydrolyzed coagulant; prepolymerized coagulant; leachate.
Remote Monitoring of Urban Flooding based on the Warning System of INEA-RJ, Brazil
by Alfredo Akira Ohnuma Jr, Fernanda Santa Barbara Vissirini, Rosa Maria Formiga
Abstract: The purpose of this article is to analyze the flood-warning systems (SAC) through remote management (to prevent or mitigate the risk of extreme hydrological events) carried out by the State Institute for the Environment (INEA-RJ) for the State of Rio de Janeiro. The methodology involves selecting hydological monitoring stations located in the region of the Fluminense Lowlands, Rio de Janeiro-RJ, obtained by the SAC, together with the observed data of the water levels of the river and rainfall. The data which are made available by the system every ten minutes in real time, are automatically transmitted to the cell phone, when there is a forecast of heavy rain and a serious overflow of volumes of water in the channels. The results of monitoring the level suggested there was a period of about 2 hours and 15 minutes from the time the river reached an 80% spillover rate until the complete overflow of the volume of water in the section monitored at the bridge of the River Capivari, in the town of Duque de Caxias-RJ-Brasil. The remote management of the rain recommended by the INEA will make it possible to broaden its range of measures for planning and response to urban risks, and in particular to provide an instant response to the civil defence of the town, as well as to the most vulnerable areas and thus prevent disasters from extreme hydological events.
Keywords: prevention; urban flooding; disasters; extreme hydrological events.
Sources and Cancer Risks Assessment of Polycyclic Aromatic Hydrocarbons in Particulate Matter and Surface soils in Kunming, China
by Xinhao Wu, Xiaoxia Yang, Xiao Li, Xiaoman Li, Fengxia Han, Xuejun Pan
Abstract: The concentrations, possible sources and cancer risks of polycyclic aromatic hydrocarbons (PAHs) in fine particulate matter (PM2.5), total suspended particles (TSP) and surface soils collected from the same sampling spots were analyzed in Kunming, China. The total PAH concentrations in PM2.5, TSP and surface soil were 7.44-25.64 ng/m3, 17.73-48.35 ng/m3 and 72.16-442.40 ng/g dry weight, respectively. Pyrogenic origins (especially coal, wood and fossil fuel combustion) were identified as the main sources of PAHs in particulate matter (PM) and surface soils based on the diagnostic ratios and principal component analysis (PCA). The values of incremental lifetime cancer risk (ILCRs) that exposed to PAHs in PM2.5 were slightly larger than 10-4, indicating high potential of carcinogenic risk. And the values of ILCRs showed that particle-bound PAHs with higher potential carcinogenic ability than soil PAHs. Moreover, compared with adults, the values of cancer risk among children were always higher.
Keywords: polycyclic aromatic hydrocarbons; fine particulate matter; total suspended particles; surface soils; cancer risks.
Feasibility studies of using domestic wastewater for landscape irrigation purposes near a nuclear power plant
by Muhammad Saleem, Usman Jabbar
Abstract: The current domestic wastewater treatment unit in a local Nuclear Power Plant (Karachi) was found to bring major wastewater parameters to ranges suitable for landscape irrigation purposes according to US-EPA and Jordanian standards, except for TSS, BOD5, and coliforms. The inclusion of a sedimentation basin was found to reduce suspended solids to 30 mg/l and coliform by 40-50%, which was a relatively insignificant improvement. In order to improve the wastewater treatment facility further, laboratory runs were conducted by passing treated wastewater through a Slow Sand Filtration (SSF) unit for 168 hours. SSF unit was found to reduce TSS by 81.7%, BOD5 by 71.7% and fecal coliforms by 99.75%. As a result, it is recommended to include both a sedimentation basin as well as an SSF unit in the wastewater treatment train in the future to allow treated wastewater from the Nuclear Power Plant to meet international standards for landscape irrigation.
Keywords: Treated wastewater; Landscape irrigation; Nuclear Power Industry; sedimentation; fecal coliforms; SSF.
The Application of Crosslinking Oil Palm Trunk Starch (C-OPTS) Coagulants for Landfill Leachate Treatment
by Mohd Suffian Yusoff, Hamidi Abdul Aziz, Mohd Faiz Muaz Ahmad Zamri
Abstract: Coagulation-flocculation has been extensively used as a semi-aerobic landfill leachate treatment, prior to other treatment methods. Polyaluminium Chloride (PAC) coagulants is prominent in landfill leachate treatment, however the application of PAC may introduce potentially harmful residuals into the aquatic environment. In this study, crosslinked starch-based coagulants had been produced from oil palm trunk waste (C-OPTS). To date, no attempt has been made to avail crosslinked oil palm trunk starch application in landfill leachate treatment. Based on the results, C-OPTS can be employed as coagulants. Jar test results had ascertained that optimum pH and dosages value for C-OPTS and PAC Indeed, no pH adjustment was required for C-OPTS and its optimum dosage was only one-eighth of PAC optimum dosage. Therefore, C-OPTS would be an alternative coagulant substituting PAC, depending on leachate condition. The overall findings concluded that C-OPTS were feasible for landfill leachate treatment in terms of coagulation performance and sustainable environmental management.
Keywords: Starch; Oil Palm Trunk; Natural Coagulant and Landfill Leachate.
Polyaluminium chloride and flocculation aids for color removal from biologically treated textile mill effluent
by Gemima Santos Arcanjo, Pedro Henrique Guerra Alves, Rafael Kopschitz Xavier Bastos, Leonardo Oliveira Cordeiro
Abstract: The objective of this work was to construct the polyaluminium chloride (PACl) diagram of coagulation for secondary effluent from a textile industry in order to determine the best coagulant dose and coagulation pH. PACl doses vary between 200 and 450 mg/L with pH values from 4.5 to 8.0. In addition, it was evaluated the effect of applying a copolymer of acrylamide and sodium-acrylate as a flocculation aid and the addition of a decolorant, composed by dicyandiamide, to increase the color removal efficiency, at the best coagulant dose and pH obtained. Apparent color removal of 70% was reached in the pH range and coagulant dose predicted for the enhanced coagulation process: high coagulant doses, between 200 and 450 mg/L; and low coagulation pH, between 4.5 and 5.0. The application of the copolymer and the decolorant resulted in an apparent color removal between 10 and 30% less than the efficiency obtained with PACl application. These results indicate the need for further studies to optimize the application of these combined products with the PACl and improve the color removal from textile mill effluent.
Keywords: Polyaluminium chloride; enhanced coagulation; textile effluent.