Deep drainage technique utilised for flood mitigation in low-land coastal areas of Australia during the late 1960s has resulted in the generation of sulphuric acid in soil by the oxidation of pyritic materials. Further degradation of the subsurface environment with widespread contamination of the underlying soil and groundwater presents a major and challenging environmental issue in acid sulphate soil (ASS) terrains. Although several ASS remediation techniques recently implemented in the floodplain of Southeast Australia including operation of gates, tidal buffering and lime injections could significantly control the pyrite oxidation, they could not improve the long-term water quality. More recently, permeable reactive barriers (PRBs) filled with waste concrete aggregates have received considerable attention as an innovative, cost-effective technology for passive in situ clean up of groundwater contamination. However, long-term efficiency of these PRBs for treating acidic groundwater has not been established. This study analyses and evaluates the performance of a field PRB for treating the acidic water over 2.5 years. The pilot-scale alkaline PRB consisting of recycled concrete was installed in October 2006 at a farm of southeast New South Wales for treating ASS-impacted groundwater. Monitoring data of groundwater quality over a 30 month period were assessed to evaluate the long-term performance of the PRB. Higher pH value (~pH 7) of the groundwater immediately downstream of the PRB and higher rates of iron (Fe) and aluminium (Al) removal efficiency (>95%) over this study period indicates that recycled concrete could successfully treat acidic groundwater. However, the overall pH neutralising capacity of the materials within the barrier declined with time from an initial pH 10.2 to pH 7.3. The decline in the performance with time was possibly due to the armouring of the reactive material surface by the mineral precipitates in the form of iron and aluminium hydroxides and oxyhydroxides as indicated by geochemical modelling.

Organic waste, as a main constituent of municipal solid waste, has as well as solid biomass a high potential for biogas generation. Despite the importance of biogas generation from these materials, the availability of large-scale biogas processes lacks behind the demand. A newly developed double-stage solid-liquid biogas process, consisting of an open hydrolysis stage and a fixed-bed methane reactor, allows the biogas production from almost all biodegradable solid waste and renewable resources like maize, grass, sugar cane, etc. Furthermore, residues from industrial processes, like the glycerine waste water from biodiesel production, can also be converted into biogas successfully. Due to the strong separation of hydrolysis and methanation, the process is extremely stable. No malfunction has been detected so far. The open hydrolysis releases CO₂ and allows oxidation of sulfur. Consequently, the biogas has a high methane (>72%) and low H₂S concentration (<100 ppm). Stirrers or other agitation equipment are not necessary; only liquids are pumped. The biogas generation becomes controllable for the first time; thus, the actual generation can be easily adapted to the consumption.

The effect of waterborne zinc on survival, growth, and feed intake of Indian major carp, Cirrhinus mrigala (Hamilton), advanced fry was studied under laboratory condition. Survival rates of C. mrigala advanced fry (2.71 ± 0.49 g) after 30 days exposure to control (0.01), 0.03, 0.06, 0.10, and 0.15 mg/L zinc using the static renewal method in freshwater at pH 7.3 ± 0.2, temperature 26 ± 2°C, and total hardness 114 ± 16 mg/L as CaCO₃ were 100%. Growth of the fish exposed to 0.10 and 0.15 mg/L of zinc was significantly lower (P < 0.05) than in control (0.01), 0.03, and 0.06 mg/L of zinc after 30 days of exposure. However, there were no significant differences (P > 0.05) in fish growth between 0.03 and 0.06 mg/L zinc concentrations. Feed intake rates were significantly (P < 0.05) reduced in the fish exposed to 0.10 mg/L and higher levels of zinc. The zinc accumulation in the whole body of the fish increased with increasing concentrations of the metal.

This paper describes the possible inundation scenarios under sea level rise conditions due to global climate change with particular reference to Nagoya, Japan. The study was carried out by using a two-dimensional sea model integrated with one-dimensional river flow model and two-dimensional overland flow model. For the connections of models, the upstream discharge or downstream water level in each grid is considered as the boundary conditions. The governing equations used for the analysis have been solved by finite volume method. The analysis results implicate that some parts of densely populated coastal area of Nagoya city will be vulnerable to inundation if the sea level rise due to global warming by 1 m. Moreover, the performances of existing sewer system and inundation scenario under various conditions have been analyzed.

Concrete is usually the preferred material for construction of structures in contact with water during their service life. Early age exposure to water is beneficial for curing of concrete structures. However, the pollution of water from freshly cast concrete in contact with water has not been investigated in detail. A significant increase in the alkalinity has recently been observed in a stream in contact with freshly installed concrete culverts. High alkalinity has caused distress to fresh water fish in the stream. A preliminary laboratory study was commenced to explore the effect of leaching of alkali into water from freshly placed concrete. Freshly cast concrete specimens were exposed to fresh water, covering a range of conditions observed in the field such as volume of concrete/volume of water, age of exposure and cement content. Analysis of the results indicated that early age contact with fresh concrete can lead to an increase in the pH levels of water up to 11, similar to the levels of pH observed in pore water inside freshly cast concrete. It was noted that until an age of 4 days from casting of concrete, the age of exposure does not significantly affect the changes in the peak pH levels of water. Continuous monitoring of water in contact with concrete also indicated that the pH levels diminish with time, which is attributed to the possible reaction of calcium hydroxide with atmospheric carbon. The paper will present the experimental study, the results, analysis and outcomes as well as planning of a more comprehensive study to observe possible ways of reducing the leaching of alkali from freshly placed concrete.

Selective extraction techniques followed by batch adsorption experiments and statistical analyses were employed to investigate the adsorption behavior of bisphenol A (BPA) onto the natural surface coatings samples (NSCSs) and surficial sediments (SSs) and estimate the relative contribution of components (i.e. Fe oxides, Mn oxides, organic materials and residues) to the total BPA adsorption. The results indicate that nonlinear Langmuir model can describe the adsorption behavior of BPA on the NSCSs and SSs before and after extraction treatments. The removal of Mn oxides from the NSCSs and SSs caused a significant increase in BPA adsorption, which implied that Mn oxides inhibited BPA adsorption onto solid matrix, and Fe oxides played a positive role in BPA adsorption onto the NSCSs and SSs. However, the removal of organic materials (OMs) led to a dramatic decrease in BPA adsorption, suggesting considerable amounts of BPA adsorbed onto OMs in the NSCSs and SSs. This study may provide important insights into the understanding of the transport and ultimate fate of BPA in the aquatic environments.

Municipal solid waste (MSW) source-classified collection represents an advancement in resource recycling and secondary pollution control in China. Comparative experiments were performed to assess the effect of a newly-established MSW source-classified collection system on polycyclic aromatic hydrocarbons (PAHs) in bottom ash from an incinerator (BA), fly ash from a boiler (FAB) and fly ash from a bag filter (FABF) of a full-scale MSW incinerator in China. Compared with FAB or FABF, PAHs were mainly concentrated in BA with a range of 1,961.0-2,420.2 μg/kg. Total amounts of 16 high priority PAHs in BA, FAB and FABF from the classified MSW incineration were significantly reduced by 19.0%, 42.4% and 59.8% respectively in comparison with those from the traditional mixed MSW incineration. Moreover, the toxic equivalent quantity (B[a]Peq) of carcinogenic PAHs in these three kinds of residues from the classified MSW incineration were significantly decreased, with the maximum decrease observed in FABF. As a result of source-classification with effective presorting and dewatering, plastics and metals in the MSW were lower, but combustibles and heat values of the MSW increased. Due to variations of the characteristics of the feed waste, complete combustion conditions including continuous higher incineration temperature, lower CO concentration and higher air excess ratio were observed during the process of classified MSW incineration. Incineration temperature and CO concentration showed a negative and positive correlation, respectively, with total PAHs, indicating that incomplete combustion products such as PAHs could be reduced by controlling combustion conditions directly related to properties of the feed waste. The newly established MSW source-classified collection process could be a feasible method for reducing PAHs formation and emission in residues from MSW incineration.

Industrial wastes generated from tanneries located in the southwestern part of Dhaka, pose serious threat to the environment. Surface accumulation of trivalent chromium reaching as high as 28,000 mg/kg have been encountered at 1 km distance from the waste lagoon. In contrast, maximum concentration of hexavalent chromium is about 1 mg/kg, and is very irregularly distributed all over the area. Although soil pH is alkaline in general, a sharp drop of pH down to 3.4 has been observed at some locations. Furthermore, high chloride (Cl) and lead (Pb) concentrations pose risk for city's groundwater quality, of which Pb is vulnerable for any chelate-assisted phytoremediation as it can enhance its mobility. Scanning electron microscope study showed chromium within the structure of clay minerals, mainly illite-smectite, and also as chlorite-chromian. Presence of lepidocrocite indicates a rather reactive phase which can undergo reductive dissolution and release Cr in the environment.

This study investigates the impact of accidental fires and the record of recent environmental change held within a long peat core taken on Burbage Moor in the south Pennines (UK). The core has been subjected to mineral magnetic, heavy metal (via inductively coupled plasma-optical emission spectroscopy) and radiometric analyses. It may be subdivided into three zones reflecting the infilling of a basin-like depression and reveals pre-industrial conditions and the impact of recent atmospheric particulate pollution. Peak concentrations of heavy metals are relatively high (e.g., peak Pb concentration is 1,124 mg kg⁻¹). However, the mineral magnetic and heavy metal depth profiles may have been affected by post-depositional changes. The core has been influenced by drainage and a number of moor fires. The area was extensively burnt in 1976, though assessing the impact of this event is problematic, due to the perturbed nature of the profile and the inability to provide a reliable chronology.

In the present work, rapid test methods for field screening of soil for Cu, Ni, and Pb content are presented. They are based on commercially obtainable Microquant tests (Merck, Germany), which are originally developed for water analysis. The same type of color reaction was also used for the determination of heavy metals in soil extracts: Reagents to form colored metal complexes are cuprizone for Cu, dimethylglyoxime for Ni, and dithizone for Pb. The experimental conditions for the colorimetric determination of these metals in the soil extracts were studied and additionally modified. An aqua regia solution (HCl/HNO₃, 3:1) was used for the rapid extraction of metals from soil. To establish accuracy, results obtained with the proposed test methods were compared with those obtained with the standard laboratory method using microwave digestion and flame atomic absorption spectrometry (FAAS). Real soil samples containing metals at background levels generally yielded approximately 50% of the total content obtained with the standard FAAS method. High recovery values of spiked samples confirm that the colorimetric methods are unaffected by soil matrix effects.