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Immobilized Trametes versicolor BCC 8725 was evaluated for the biodegradation of the organic components of four different types of landfill leachate collected at different time periods and locations from the Nonthaburi landfill site of Thailand in batch treatment. The effects of carbon source, ammonia and organic loading on colour, biochemical oxygen demand (BOD) and chemical oxygen demand (COD) removal, and the reuse of immobilized fungi were investigated. It was found that fungi can remove 78% of colour, reduce BOD by 68% and reduce COD by 57% in leachate within 15 days at optimum conditions. Organic loading and ammonia were the factors that affected the biodegradation. When immobilized T. versicolor on polyurethane foam (PUF) was subjected to repeated use for treatment over the course of three cycles, the decolourization efficiency of the first and the second cycle was very similar, whereas the third cycle was about 20% lower than the first cycle under similar conditions. The obtained removal of colour, BOD and COD indicates the effectiveness of fungi for leachate treatment with high organic loading and varied leachate characteristics. [ABSTRACT FROM PUBLISHER]

Two-stage membrane bioreactor (MBR) system was applied to the treatment of landfill leachate from a solid waste disposal site in Thailand. The first stage anoxic reactor was equipped with an inclined tube module for sludge separation. It was followed by an aerobic stage with a hollow fiber membrane module for solid liquid separation. Mixed liquor sludge from the aerobic reactor was re-circulated back to anoxic reactor in order to maintain constant mixed liquor suspended solids (MLSS) concentration in the aerobic reactor. The removal of micro-pollutants from landfill leachate along the treatment period of 300 days was monitored. The results indicated that two-stage MBRs could remove biochemical oxygen demand (BOD), chemical oxygen demand (COD) and NH4+ by 97, 87 and 91% at steady operating condition. Meanwhile organic micro-pollutant removals were 50-76%. The removal efficiencies varied according to the hydrophobic characteristic of compounds but they were improved during long-term MBR operation without sludge discharge. [ABSTRACT FROM AUTHOR]

Kham Bon landfill site is one of many municipality waste disposal sites in Thailand which are in an unsanitary condition. The site has been receiving municipality wastes without separating hazardous waste since 1968. Heavy metals including, Pb, Cr and Cd are found in soil and groundwater around the site, posing a health risk to people living nearby. In this research, contamination transport modelling of Pb, Cr and Cd was simulated using MODFLOW for two periods, at the present (2010) and 20 years prediction (2030). Model results showed that heavy metals, especially Pb and Cr migrated toward the north-eastern and south-eastern direction. The 20 years prediction showed that, heavy metals tend to move from the top soil to the deeper aquifer. The migration would not exceed 500 m radius from the landfill centre in the next 20 years, which is considered to be a slow process. From the simulation model, it is recommended that a mitigation measure should be performed to reduce the risk from landfill contamination. Hazardous waste should be separated for proper management. Groundwater contamination in the aquifer should be closely monitored. Consumption of groundwater in a 500 m radius must be avoided. In addition, rehabilitation of the landfill site should be undertaken to prevent further mobilization of pollutants. [ABSTRACT FROM AUTHOR]

This paper investigated treatment of landfill leachate collected from Nonthaburi landfill site, Thailand, by using immobilized white rot fungi, namely, Trametes versicolor BCC 8725 and Flavodon flavus BCC 17421. Effects of pH and co-substrates were investigated at different contact times. Three types of co-substrates as carbon source used in this study are glucose, corn starch and cassava. Treatment efficiency was evaluated based on color, BOD, and COD removal. Initial BOD and COD were found to be 5,600 and 34,560 mg/L, respectively. The optimum pH was found to be 4, the optimum co-substrate concentration (glucose, corn starch and cassava) was 3 g/L and the optimum contact time was 10 days for both types of fungi. Addition of glucose, corn starch and cassava as co-substrate at optimum conditions could remove 78, 74, and 66% of color, respectively for T. versicolor and 73, 68, and 60%, respectively, for F. flavus. Moreover, for T. versicolor, BOD and COD reduction of 69 and 57%, respectively, could be achieved at optimum conditions when using glucose as a co-substrate. For F. flavus, BOD and COD reduction of 66 and 52%, respectively were obtained when using glucose as a co-substrate. White rot fungi can be considered potentially useful in the treatment of landfill leachate as they can help in removing color, BOD and COD due to their biodegradative abilities. [ABSTRACT FROM AUTHOR]

Abstract: This study was undertaken to investigate the performance of aerobic thermophilic membrane bioreactor (MBR) treating raw landfill leachate from two landfill sites in Thailand (Pathumthani site and Ram Indra site). The leachates from these sites were mixed in different proportions to produce a BOD/COD ratio of 0.39, 0.57, and 0.65, which was investigated in 3 experimental runs. The COD, ammonia, and TKN composition of the mixed leachate was 12,000, 1700 and 1900 mg/L, respectively. BOD was supplemented with glucose and soy protein. The system was operated at 45°C and at a hydraulic retention time (HRT) of 24 hrs. The membrane used was a ceramic membrane with an ‘‘outside-in’’ flow mode and consisted of 22 open fibres with an inner diameter of approximately 2 mm. The COD removal rate increased from an average value of 62–79% while ammonia removal efficiency decreased from 75 to 60% with gradual increase in BOD. Furthermore, a high BOD removal efficiency (97–99%) was also observed. This clearly indicates that thermophilic system is highly suitable for COD and BOD removal especially at elevated organic loading. However, the system does not favor high nitrogen content wastewaters as the ammonia removal efficiency dropped with increasing BOD/COD ratio. Similar trends were found in TKN analysis as well. However, this system could serve as a pretreatment in removing ammonia. The concentrations of soluble and bound extra-cellular polymeric substances (EPS) found in thermophilic MBR were higher when compared to the corresponding concentrations in a mesophilic MBR, which led to a higher rate of fouling in the thermophilic membrane. [Copyright &y& Elsevier]

Experiments were conducted to investigate the feasibility of applying constructed wetlands to treat a sanitary landfill leachate containing high nitrogen (TN) and bacterial contents. Two-pilot scale subsurface-flow constructed wetland (SFCW) units located at the Asian Institute of Technology, Thailand, campus, were fed with a synthetic wastewater and landfill leachate collected from a nearby sanitary landfill. Under the tropical conditions (temperature of about 30°C), the SFCW units operating at the hydraulic retention time(HRT) of 8 days yielded the best treatment efficiencies with BOD5 removal of 91 %, TN removal of 96 %, total and fecal coliforms (TC and FC) removal of more than 99 % and cadmium removal of 99.7 %. The treatment performance was found to follow first-order reaction rate, in which the k20 values of BOD5, COD, TN, TC, FC and Cd were 0.201, 0.121, 0.247, 0.346, 0.354 and 0.690 d-1, respectively. Mass balance analysis, based on TN contents of the plant biomass and dissolved oxygen (DO) and oxidation- reduction potential (ORP) values, suggested that 88 % of the input TN were uptaken by the plant biomass; 8 % removed by nitrification-denitrification reactions and adsorption on the wetland media, while the remaining 4 % were discharged with the effluent. [ABSTRACT FROM AUTHOR]

One of the key challenges in landfill leachate management is the prevention of environmental pollution by the overflow of untreated leachate. To evaluate the feasibility of constructed wetlands (CWs) for the treatment of waste landfill leachate in tropical regions, water reduction and pollutant removal by a CW subjected to different flow patterns (i.e., horizontal subsurface flow (HSSF) and free water surface (FWS)) were examined in both rainy and dry seasons in Thailand. A pilot-scale CW planted with cattail was installed at a landfill site in Thailand. With HSSF, the CW substantially removed pollutants from the landfill leachate without the need to harvest plants, whereas with FWS, it only slightly removed pollutants. Under both flow patterns, the CW significantly reduced the leachate volume to a greater extent than surface evaporation, which is regarded as an effect of the storage pond. Additionally, water reduction occurred regardless of season and precipitation, within the range 0-9 mm d(-1). In the case of low feeding frequency, water reduction by the CW with HSSF was lower than that with FWS. However, high feeding frequency improved water reduction by the CW with HSSF and resulted in a similar reduction to that observed with FWS, which exhibited maximum evapotranspiration. In terms of water reduction, with both HSSF in conjunction with high frequency feeding and FWS, the CW provided a high degree of evapotranspiration. However, pollutant removal efficiencies with HSSF were higher than for FWS. The present study suggested that CWs with HSSF and high frequency feeding could be useful for the prevention of uncontrollable dispersion of polluted leachate in the tropical climate zone., (Copyright © 2015 Elsevier Ltd. All rights reserved.)