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This review assesses the leachate quality from waste disposal sites in tropical climate zone. Through this review, data from 228 leachate samples from 145 waste disposal sites from 18 countries in the tropical region were analyzed. The 12 types of sites were considered for the analysis based on the climatic conditions, age, and the operating condition of the site. Tropical rainforest, tropical monsoon, and tropical savanna climates were identified for the climatic zone classification. Age of site was classified as young and old. The operating conditions were classified as engineered landfill and open dump site. Eighteen leachate quality parameters were included in the analysis. Leachate pollution index indicated that young sites from tropical rainforest zone and tropical monsoon zone have higher pollution potential, while the pollution potential in tropical savanna zone did not demonstrate considerable difference in pollution potential in terms of age of the landfill. Considering the operating method of the sites, open dumpsites pose higher pollution potential. Positive correlation could be seen among biological oxygen demand, chemical oxygen demand, total dissolved solids, and total Kjeldahl nitrogen. pH negatively correlated with organic pollutants as well as heavy metals. Analysis of emerging contaminants present in landfill leachate is limited in tropical region; thus, it is recommended to conduct studies on emerging contaminants. Further, the leachate treatment options considered in tropical region are discussed in this review.

Various studies provide information about the high potential of using hollow fiber membrane contactors (HFMCs) for the recovery of dissolved methane from anaerobically treated wastewater effluent and the effects of different operating conditions on their performance. However, majority of those studies evaluated HFMCs at bench scale under favorable conditions, i.e. clean water as feed under short-term operations. This study evaluated the performance of porous HFMC and dense HFMC (in terms of dissolved methane removal efficiency and methane desorption flux) subjected to anaerobic feed during long-term operation of one month. The study will provide better understanding of the performance of HFMCs with conditions expected at large-scale wastewater treatment systems. From the results, the decrease in the performance of HFMCs and the increase in the mass transfer resistance per week under varying feed flux were determined. These relationships were utilized in a numerical model to incorporate the effect of long-term operation to evaluate the performance of upscaled HFMCs. The fit of the model with the experimental data with one month of operation was evaluated and the relative errors were 11.9 % and 15.3 % for porous HFMC and dense HFMC, respectively. Moreover, results showed that dense HFMC will provide better performance than porous HFMC if it were to be operated longer than two weeks before cleaning. The net energy for porous HFMC and dense HFMC were optimized to be 0.07 and 0.02 kWh·d

Activated sludge is one of the main processes used for wastewater treatment. Activated sludge is associated with the production of excess sludge, commonly referred to as wasted activated sludge (WAS). The handling and disposal of this sludge accounts for more than 40% of operational costs in a typical waste water treatment plant (WWTP). There were 26,000 tonnes of dry sludge produced in Melbourne during the years 2009-2010 according to the annual report by Melbourne Water and $43 million has been invested in Western Treatment Plant to improve the sludge treatment. 5840 tonnes of the sludge was collected and sent to a landfill for disposal, at a total cost of $494,210. Therefore, attention has been given to modifications to the activated sludge process with potential for minimization of excess sludge. One possible modification is the use of metabolic uncouplers, chemicals that can uncouple the energy transfer in cells and ultimately reduce activated sludge yield. The aim of this research was to evaluate two uncouplers, 3, 3’, 4’, 5-tetrachlorosalicylanilide (TCS) and para-nitrophenol (PNP also known as 4-nitrophnol or 4-NP) for their potential for reducing sludge production. A series of laboratory scale batch tests were carried out. The results obtained showed that TCS, at a concentration of 0.8 mg/L, can reduce activated sludge production by 45%, with little effect on COD removal. In comparison, a high concentration of 30 mg/L PNP was required to reduce sludge production by 30% but little effect on COD removal was observed.

Meat rendering represents one of the most important sectors of the meat industry in Australia. With industrial growth, there has been increased attention to waste management of meat wastes. One of the alternative waste management technologies attracting the meat industry attention is anaerobic digestion (AD), especially that renewable energy and cost savings are added benefits. In this study, the feasibility of anaerobic digestion of wastes generated at a meat rendering plant in Melbourne was investigated. The plant uses dissolved air flotation (DAF) to treat the wastewater before discharge to the sewer. The sludge separated is sent to landfill.

Arid and semi-arid regions are generally characterized by water scarcity and low per capita water allocation. This situation is further exacerbated when such areas are agriculturally dominated and encounter a high population growth rate. Faria watershed, Palestine, is one of these semi-arid regions where lack of proper management of natural resources, accompanied with the recent prolonged drought periods in the watershed have negatively affected the existing obtainable surface water and groundwater resources. This situation has compelled the motivation for developing optimal water allocation policies that consider the available water resources under the climatic changes in the watershed such that the socioeconomic revenue is maximized. This paper conceptually demonstrates a decision–support-system to integrate different work plans and components in order to assess the conjunctive use of the different water resources in the watershed under different management scenarios driven by climatic changes and land use planning. The framework incorporates an assessment of the existing data and future needs, a GIS framework to facilitate processing and visualization, mathematical models of surface water and groundwater a planning model to evaluate the economic ramifications for different management options, and a multi-criteria decision analysis module.