Current Environmental Engineering - Volume 1, Issue 2, 2014

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 solar ponds. 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 the water evaporation enhancement using those materials was quite limited. We have recently reported the use of solar lightabsorbing carbon-Fe3O4 particles and achieved a 230% increase in solar evaporation rate. This paper focuses on mathematical modeling of the solar evaporation process assisted by this kind of floating light-absorbing material. The proposed model was used to predict the evaporation rate of the experimental tests and results showed an acceptable compatibility between the experimental and calculated evaporation rates by an error lower than 13%.

Chromite ore processing residue (COPR) is a waste byproduct of chromate production that contains high levels of hexavalent chromium (Cr[VI]). Although the high temperature chromite process was banned in several countries, its legacy 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 to new contamination. This paper reviews the historical production and disposal practices of COPR and provides a concise overview of the different methods for addressing Cr(VI) contamination at old and new COPR sites.

Legionella pneumophila was identified in the aeration ponds of a biological wastewater treatment plant at the pulp and paper industry Borregaard, Sarpsborg, Norway. After 3 outbreaks of Legionaires’ disease reported in this area in 2005 and 2008, the aeration ponds were shut down by the Norwegian authorities in September 2008. During the shutdown of these ponds, September to December 2008, the viable counts of L. pneumophila decreased from 107 to < 10 CFU/mL measured using the International Standard growth (ISO11731) method. The aim of this work was to use amoebal coculture with Achantamoebae castellanii to recover and detect L. pneumophila from the complex microbial community in the pond during the shutdown period. This work shows that the viable counts of the environmental L. pneumophila ST 462 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 the environment may not be detected using standard culture methods. As a consequence, methodological improvements are needed 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 growth methods (according to the ISO11731), to be detected. Cells in the viable but non-culturable (VBNC) form will not be detected using the ISO 11731 standard culture method, and growth on agar media may be inhibited by other organisms and inhibitors present in complex environmental samples. The methodological procedure described in this paper may assist in providing a general more robust and sensitive approach to detect L. pneumophila in more complex environmental samples and may assist in providing improved hazard assessments.

Chitosan Grafted Silica (CGS) material was prepared by using tetraethyl-orthosilicate as grafting and/or cross linking agent. The structure of the material was characterized by SEM (Scanning Electron Microscopy), FTIR (Fourier transform infrared Spectroscopy), and BET (Brunauer, Emmett and Teller) analysis. The higher sorption potential of synthesized 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 data suggested an endothermic, spontaneous and higher stable sorption process with no structural changes at the solid-solution interface. The ΔG value was increased with an increase in temperature up to 40°C, indicating a greater driving force ensuing a higher sorption capacity. The co-efficient of correlation (R2) suggested that the sorption data was best fitted in Freundlich isotherm rather than the Langmuir isotherm, indicating a multilayer sorption. The Freundlich sorption isotherm proposed a favorable sorption of DDT as compare to DDE. The developed method was applied to real industrial waste at laboratory level. The experimental data revealed that developed method might be employed for the removal of DDT and DDE from aqueous industrial effluents before discharging them into water bodies.

In this study, palm oil mill effluent (POME) from polishing pond of palm oil mill treatment plants has been chosen to be treated in laboratory experiment using horizontal roughing (HRF) filter system. The purpose of this article was to evaluate the effect of three filter media sizes on the removals of COD, NH3-N and turbidity and as well as to evaluate the effect of three filtration rates on the removal of color, turbidity and suspended solid from POME using limestone media in HRF system. The results indicated that the removal of smaller filter media gave higher removal efficiency and larger size of filter media gave lower removal efficiency. Optimum removal of COD, NH3-N and turbidity were 27%, 51% and 32%, respectively, which were obtained at lowest filter media size (i.e. 3-6 mm). Similar result was also obtained in studying the effect of filtration rates. It was found that the optimum reduction of turbidity, suspended solid and color were up to 38.6%, 57.4%, and 34.5%, respectively, at lowest filtration rates of 0.3 m h-1. These results were supported by one-way analysis of variance (ANOVA).

HFC-1345fz (3,3,4,4,4-pentafluoro-1-butene, CF3CF2CH=CH2) is currently considered as an acceptable alternative to high global warming potential (GWP) HFCs as foam blowing agents. The tropospheric photooxidation of HFC-1345fz initiated by hydroxyl (OH) radicals is expected to be faster than the saturated HFCs because of the presence of the C-C double bond. To evaluate the tropospheric persistence of HFC-1345fz it is necessary to determine the rate coefficients of the main removal pathway in the gas-phase, i.e. its reaction with OH (kOH). In this paper, we present the first absolute measurement of kOH at 298 K as a function of total pressure (31 - 624 Torr of He). The determination of kOH has 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 was estimated from kOH and assuming a 24-h averaged OH concentration of 1×106 cm-3. Degradation route of HFC-1345fz initiated by OH radicals is compared with other atmospheric removal processes. The IR absorption cross sections, σv , of HFC-1345fz are also determined in the wavenumber range of 500-4000 cm-1 to quantify its radiative properties, such as the radiative efficiency (RE). The lifetime corrected RE for HFC-1345fz is calculated to be 0.022 W m-2 ppbv-1, which implies a negligible global warming potential. Therefore, from the kinetic and atmospheric degradation points of view, the studied hydrofluoroolefin seems to be suitable for replacing saturated HFCs as foam blowing agents, since they are shortlived species that do not contribute to the Earth’s global warming.

In developed countries, municipal wastewater treatment has historically used aerobic biological processes like activated sludge. Anaerobic processes have been used only to treat sludge resulting from aerobic processes, as well as high-strength industrial wastewaters. In aerobic processes, organic compounds combine with oxygen to form carbon dioxide and water. In this conversion, much energy is lost to air – about 20 times as much as with an anaerobic process. In contrast, 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 used successfully to treat low-strength wastewaters, including municipal wastewaters. This allows a valuable renewable energy resource 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 and energy requirements are typically lower for anaerobic processes compared to aerobic systems, even if the anaerobic systems must include post-treatment processes to achieve water quality standards. Anaerobic municipal wastewater treatment can be particularly attractive for developing countries, which are confronting rapidly increasing water pollution problems. This paper will: 1. provide an overview of anaerobic and aerobic treatment processes, including anaerobic system limitations that have 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.

Greece is a Mediterranean country where the problem of devastating wildfire occurrence is great, threatening human lives and property. In the current research, an attempt is being made to evaluate the effects of simulated silvicultural treatments in order to efficiently reduce wildfire’s’ potential severity. The evaluation is based on the establishment of 52 experimental plots of 500 m2 and the estimation of the dendrometric characteristics (diameter at breast height, basal area, total height, crown length, canopy cover, understorey composition). The total sample was composed of n=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 Crowning Indices were estimated before and after the virtual establishment of silvicultural treatments. The analysis showed that combinations of simple silvicultural interventions decreased the wildfire severity in all cases. The frontal fireline intensity was reduced by more than 70%, while the flame length was reduced to 59.1% and the spread rate to 20.6%. Despite the efficiency of the silvicultural treatments, under hazardous climatic conditions fire severity remained high for firefighting operations.