Current Environmental Engineering (v.1, #2)
Modelling of Solar Evaporation Assisted by Floating Light-Absorbing Porous Materials by Bahman A. Horri, Meng N. Chong, Xiao D. Chen, Huanting Wang (73-81).
Solar energy is one of the promising renewable energy sources for desalination of saline and brackish waters.The solar evaporation rate could be enhanced by placing light-absorbing agents on the surface or bottom of the solarponds. So far, different materials such as various dyes, blackened wet jute cloth, black plastic bubble sheets, black rubber,floating porous plates, etc. were used to induce the solar evaporation rate, but the evaporation results showed that thewater evaporation enhancement using those materials was quite limited. We have recently reported the use of solar lightabsorbingcarbon-Fe3O4 particles and achieved a 230% increase in solar evaporation rate. This paper focuses onmathematical modeling of the solar evaporation process assisted by this kind of floating light-absorbing material. Theproposed model was used to predict the evaporation rate of the experimental tests and results showed an acceptablecompatibility between the experimental and calculated evaporation rates by an error lower than 13%.
Review of Chromite Ore Processing Residue (COPR): Past Practices, Environmental Impact and Potential Remediation Methods by Kevin Freese, Robert Miller, Teresa J. Cutright, John Senko (82-90).
Chromite ore processing residue (COPR) is a waste byproduct of chromate production that contains high levelsof hexavalent chromium (Cr[VI]). Although the high temperature chromite process was banned in several countries, itslegacy still exists at numerous contaminated sites. For instance, New Jersey alone has over 2 million tons of waste COPR.Legacy sites are confounded by the fact that a few countries still produce COPR during chromate extraction that leads tonew contamination. This paper reviews the historical production and disposal practices of COPR and provides a conciseoverview of the different methods for addressing Cr(VI) contamination at old and new COPR sites.
Detection of Legionella pneumophila in a Biological Treatment Plant by Co- Cultivation with Acanthamoeba castellanii by Else M. Fykse, Tone Aarskaug, Janet M. Blatny (91-99).
Legionella pneumophila was identified in the aeration ponds of a biological wastewater treatment plant at thepulp and paper industry Borregaard, Sarpsborg, Norway. After 3 outbreaks of Legionaires' disease reported in this area in2005 and 2008, the aeration ponds were shut down by the Norwegian authorities in September 2008. During the shutdownof these ponds, September to December 2008, the viable counts of L. pneumophila decreased from 107 to < 10 CFU/mLmeasured using the International Standard growth (ISO11731) method. The aim of this work was to use amoebal coculturewith Achantamoebae castellanii to recover and detect L. pneumophila from the complex microbial community inthe pond during the shutdown period. This work shows that the viable counts of the environmental L. pneumophila ST462 outbreak strain present in the pond samples during shutdown, was increased from 0-10 CFU/mL (no amoebae added)to 107 -108 CFU/mL in co-culture with A. castellanii. This indicates that pathogenic L. pneumophila isolates present in theenvironment may not be detected using standard culture methods. As a consequence, methodological improvements areneeded to ensure more reliable detection and isolation of Legionella. By using amoebal co-culture, the concentration of L.pneumophila increased by 5-7 log units, allowing low concentrations and bacteria not detected using standard growthmethods (according to the ISO11731), to be detected. Cells in the viable but non-culturable (VBNC) form will not bedetected using the ISO 11731 standard culture method, and growth on agar media may be inhibited by other organismsand inhibitors present in complex environmental samples. The methodological procedure described in this paper mayassist in providing a general more robust and sensitive approach to detect L. pneumophila in more complex environmentalsamples and may assist in providing improved hazard assessments.
A Novel Material for Removal of Organochlorine Pesticides from Aqueous Environment: Kinetics and Thermodynamics Investigations by Abdul Ghaffar, Azhar Mashiatullah, Naveed Iqbal (100-110).
Chitosan Grafted Silica (CGS) material was prepared by using tetraethyl-orthosilicate as grafting and/or crosslinking agent. The structure of the material was characterized by SEM (Scanning Electron Microscopy), FTIR (Fouriertransform infrared Spectroscopy), and BET (Brunauer, Emmett and Teller) analysis. The higher sorption potential ofsynthesized material for organo-chlorine pesticides (OCPs) like DDT and DDE was attributable to its large surface area,porous rigid structure and active sites such as -OH, -NH2, and -CONH2. Most removal of DDT (94±2.9%) and DDE(86 ±1.8%) was achieved at 40°C and pH 6 with agitation of 2 and 3 hours, respectively. The thermodynamics datasuggested an endothermic, spontaneous and higher stable sorption process with no structural changes at the solid-solutioninterface. The ΔG value was increased with an increase in temperature up to 40°C, indicating a greater driving forceensuing a higher sorption capacity. The co-efficient of correlation (R2) suggested that the sorption data was best fitted inFreundlich isotherm rather than the Langmuir isotherm, indicating a multilayer sorption. The Freundlich sorption isothermproposed a favorable sorption of DDT as compare to DDE. The developed method was applied to real industrial waste atlaboratory level. The experimental data revealed that developed method might be employed for the removal of DDT andDDE from aqueous industrial effluents before discharging them into water bodies.
Using Horizontal Roughing Filter as an Effective Post-Treatment System for Palm Oil Mill Effluent (POME): Effect of Media Sizes and Filtration Rates by Ali Huddin Ibrahim, Irvan Dahlan, Mohd N. Adlan, Arezoo F. Dashti (111-117).
In this study, palm oil mill effluent (POME) from polishing pond of palm oil mill treatment plants has beenchosen to be treated in laboratory experiment using horizontal roughing (HRF) filter system. The purpose of this articlewas to evaluate the effect of three filter media sizes on the removals of COD, NH3-N and turbidity and as well as toevaluate the effect of three filtration rates on the removal of color, turbidity and suspended solid from POME usinglimestone media in HRF system. The results indicated that the removal of smaller filter media gave higher removalefficiency and larger size of filter media gave lower removal efficiency. Optimum removal of COD, NH3-N and turbiditywere 27%, 51% and 32%, respectively, which were obtained at lowest filter media size (i.e. 3-6 mm). Similar result wasalso obtained in studying the effect of filtration rates. It was found that the optimum reduction of turbidity, suspendedsolid and color were up to 38.6%, 57.4%, and 34.5%, respectively, at lowest filtration rates of 0.3 m h-1. These resultswere supported by one-way analysis of variance (ANOVA).
Atmospheric Implications of the Emission ofCF3CF2CH=CH2 (HFC 1345fz) as a Consequence of its Use as Foam Blowing Agents by Elena Jimenez, Sergio Gonzalez, María Antinolo, Jose Albaladejo (118-125).
HFC-1345fz (3,3,4,4,4-pentafluoro-1-butene, CF3CF2CH=CH2) is currently considered as an acceptablealternative to high global warming potential (GWP) HFCs as foam blowing agents. The tropospheric photooxidation ofHFC-1345fz initiated by hydroxyl (OH) radicals is expected to be faster than the saturated HFCs because of the presenceof the C-C double bond. To evaluate the tropospheric persistence of HFC-1345fz it is necessary to determine the ratecoefficients of the main removal pathway in the gas-phase, i.e. its reaction with OH (kOH). In this paper, we present thefirst absolute measurement of kOH at 298 K as a function of total pressure (31 - 624 Torr of He). The determination of kOHhas been performed by the pulsed laser photolysis - laser induced fluorescence technique using H2O2 and HNO3 as OHprecursor.A global tropospheric lifetime of HFC-1345fz due to the reaction with OH radicals (τOH) of around 9 days wasestimated from kOH and assuming a 24-h averaged OH concentration of 1x106 cm-3. Degradation route of HFC-1345fzinitiated by OH radicals is compared with other atmospheric removal processes. The IR absorption cross sections, σv , ofHFC-1345fz are also determined in the wavenumber range of 500-4000 cm-1 to quantify its radiative properties, such asthe radiative efficiency (RE). The lifetime corrected RE for HFC-1345fz is calculated to be 0.022 W m-2 ppbv-1, whichimplies a negligible global warming potential. Therefore, from the kinetic and atmospheric degradation points of view, thestudied hydrofluoroolefin seems to be suitable for replacing saturated HFCs as foam blowing agents, since they are shortlivedspecies that do not contribute to the Earth's global warming.
Anaerobic Municipal Wastewater Treatment: A Beneficial Option for Developing Countries by Melanie L. Sattler (126-135).
In developed countries, municipal wastewater treatment has historically used aerobic biological processes likeactivated sludge. Anaerobic processes have been used only to treat sludge resulting from aerobic processes, as well ashigh-strength industrial wastewaters. In aerobic processes, organic compounds combine with oxygen to form carbondioxide and water. In this conversion, much energy is lost to air - about 20 times as much as with an anaerobic process. Incontrast, anaerobic processes produce methane, which can be used as a renewable energy source. In recent years,anaerobic reactor technology has advanced, and studies have demonstrated that anaerobic processes can be usedsuccessfully to treat low-strength wastewaters, including municipal wastewaters. This allows a valuable renewable energyresource to be tapped. In general, anaerobic systems can remove 75-95% biochemical oxygen demand (BOD), and 70-98% chemical oxygen demand (COD), and up to 100% total suspended solids (TSS). Capital costs, operational costs andenergy requirements are typically lower for anaerobic processes compared to aerobic systems, even if the anaerobicsystems must include post-treatment processes to achieve water quality standards. Anaerobic municipal wastewatertreatment can be particularly attractive for developing countries, which are confronting rapidly increasing water pollutionproblems. This paper will:;1. provide an overview of anaerobic and aerobic treatment processes, including anaerobic system limitations thathave been overcome by recent advances.;2. discuss benefits and limitations of anaerobic wastewater treatment processes compared with aerobic processes.;3. summarize recent studies of anaerobic processes for treating municipal wastewater.
Evaluating the Effects of Simulated Silvicultural Treatments and Management on Wildfire Severity in Pinus halepensis Mill. Even-Aged Stands by Thekla Tsitsoni, Dimitrios Raptis, Dimitrios Zagas, Theocharis Zagas (136-147).
Greece is a Mediterranean country where the problem of devastating wildfire occurrence is great, threateninghuman lives and property. In the current research, an attempt is being made to evaluate the effects of simulatedsilvicultural treatments in order to efficiently reduce wildfire's' potential severity. The evaluation is based on theestablishment of 52 experimental plots of 500 m2 and the estimation of the dendrometric characteristics (diameter at breastheight, basal area, total height, crown length, canopy cover, understorey composition). The total sample was composed ofn=1488 Pinus halepensis individuals, while the topographic parameter of slope steepness was estimated for each plot.Based on the NEXUS wildfire simulator software, critical fire hazard indicators such as the Torching and CrowningIndices were estimated before and after the virtual establishment of silvicultural treatments. The analysis showed thatcombinations of simple silvicultural interventions decreased the wildfire severity in all cases. The frontal fireline intensitywas reduced by more than 70%, while the flame length was reduced to 59.1% and the spread rate to 20.6%. Despite theefficiency of the silvicultural treatments, under hazardous climatic conditions fire severity remained high for firefightingoperations.