Leachate collection systems consist of a series of pipes installed beneath the waste at the base of a landfill. The liquid drains toward a central location where it is pumped and then treated, discharged, or recirculated. In some landfills, solid precipitates form in the collection system resulting in clogging and malfunctions of the drainage system. The formation of the precipitates is linked to the chemical and biological stability of the leachate generated within the landfill. To control the formation of precipitates and prevent clogging of leachate collection systems, it is important to understand factors that influence leachate characteristics. Ashes from municipal solid waste (MSW) combustion are either placed in monofills or combined with traditional solid waste, and sludges and biosolids from wastewater and drinking water treatment plants when landfilled. The ashes, depending on the type of combustion process, contain high concentrations of metals and non-biodegradable materials. As the waste degrades, oxygen in the landfill is consumed and the leachate becomes anaerobic. The reducing environment allows for greater solubility of metals. This research tested ashes from three different Waste-to-Energy (WTE) facilities to understand better the role MSW fly ash and MSW bottom ash in the chemical make-up of landfill leachate. Two different types of batch tests were used to analyze the leaching behavior. First, a contact time batch test with a range of different contact times was used to assess the rate at which different elements reach equilibrium. This was followed by a sequential extraction batch test that predicted the total amount of soluble material in the ashes. The chemical characteristics of the leachate produced by the ashes were understood and the leaching behaviors analyzed, dominant chemical factors that influence the formation of precipitates were identified. This data produced a better understanding of the roles of WTE ashes in the production of precipitates in leachate collection systems.

Heavy metal contamination is a serious concern throughout the world. Increased concentrations in drinking water have many negative impacts on human health. Limestone is an inexpensive and simple media for removing high concentrations of heavy metals from drinking water supplies. Ferric based media is commonly used to remove zinc, cadmium, lead, arsenic and other heavy metals. The drinking water standards set by the US EPA for cadmium, zinc and arsenic are 0.005 mg/L, 5 mg/L and 0.010 mg/L respectively. Bangladesh, parts of India, China and the United States have high concentrations of arsenic in drinking water. Although many technologies exist for heavy metal removal, most of these are complicated and are associated with high costs making them ineffective and unfavorable to be used in impoverished areas. We propose a novel method that combines the benefits of limestone with the capacity of ferric media in an iron-coated limestone based material. Samples of water with various concentrations of zinc and cadmium were prepared and batch tests were performed using both uncoated and iron coated limestone and are compared in removal efficiency. Kinetics studies showed that zinc is removed to a maximum level after 24 hours, while cadmium takes only 15 minutes. The effect of pH on removal of heavy metals was also studied. Metals are analyzed using Inductively Coupled Plasma Emission Spectroscopy (ICP-ES). Limestone is readily available and is also easy to coat with iron, making this material a cost effective and affordable method to be used by developing countries.

Partial Nitritation/Anammox process (deammonification process), by which occurs oxidation of ammonium to nitrogen gas by autotrophic bacteria in anaerobic conditions, considered to be cost-effective and environmentally friendly method of nitrogen removal. Present research work focuses on achieving a high nitrogen removal degree, thanks to Anammox bacteria, while providing the best performance of the ongoing process. Integrated fixed-film activated sludge (IFAS) reactor was supplied with the main stream of the wastewater after UASB reactor, characterized by low concentration of nitrogen and organic matter. The bacteria ability to accommodate, were tested in the biofilm and in the activated sludge, depending on the different stages in which the process were being conducted. Batch test, such as Specific Anammox Activity (SAA), Nitrate Uptake Rate (NUR) and Oxygen Uptake Rate (OUR), were used for the evaluation of activity of various groups of bacteria. On the basis of laboratory analysis verified the values obtained from the batch tests. It was determined that a high degree of nitrogen removal (92% of NH4-N) was achieved thanks to the dominant activity of the Anammox bacteria, with low participation of other groups of bacteria. It was also proved, that Anammox bacteria activity were overwhelming in the biofilm. Dominant role of Ammonium Oxidizing Bacteria (AOB) was associated with high activity of Anammox bacteria, which together satisfyingly out-competed Nitrite Oxidizing Bacteria (NOB) and heterotrophic bacteria. It has been shown that Anammox bacteria quickly adapt to the new conditions and they are able to assume a dominant role, even in the case of inoculation of the reactor with the sludge from SBR. This allows conclude, that in the case of operational problems, the reactor can be supplied from another source, in order not to inhibit the process.