This paper reviews both heterotrophic and autotrophic processes for the removal of nitrate from water supplies. The most commonly used carbon sources in heterotrophic denitrification are methanol, ethanol and acetic acid. Process performance for each feed stock is compared with particular reference nitrate and nitrite residual and to toxicity potential. Autotrophic nitrate removal has the advantages of not requiring an organic carbon source; however the slow growth rate of autotrophic bacteria and low nitrate removal rate have contributed to the fact that relatively few full scale plants are in operation at the present time.

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Disinfection by-products (DBPs) have heterogeneous structures which are suspected carcinogens as a result of reactions between NOMs (Natural Organic Matter) and oxidants/disinfectants such as chlorine. Because of variability in DBPs characteristics, eliminate completely from drinking water by single technique is impossible. The current article reviews removal of the precursors and DBPs by different membrane filtration methods such as Microfiltration (MF), Ultrafiltration (UF), Nanofiltration (NF) and Reverse Osmosis (RO) techniques. Also, we provide an overview of existing and potentially Membrane filtration techniques, highlight their strengths and drawbacks. MF membranes are a suitable alternative to remove suspended solids and colloidal materials. However, NOMs fractions are effectively removed by negatively charged UF membrane. RO can remove both organic and inorganic DBPs and precursors simultaneously. NF can be used to remove compounds from macromolecular size to multivalent ions.

Background: Composting process is a feasible biological treatment for the recycling of municipal solid wastes as a soil amendment. The principal requirement of compost for it to be safely used in soil is a high degree of stability or maturity, which implies stable organic matter content as well as the absence of phytotoxic compounds and plant or animal pathogens. Objectives: At the present study, the maturity and stability of composted municipal solid wastes at a biocompost plant was evaluated. Materials and Methods: For the assessment of compost maturity, important parameters including temperature, moisture content, pH, electrical conductivity, carbon-to-nitrogen (C/N) ratio, microbial parameters including Salmonella, total and fecal coliforms were measured during the composting process (80 days). In addition, phytotoxicity as seed germination index and heavy metals concentration (Zn, Cu, Cr, Ni, Cd and Pb) was determined at the end of the composting time. Results:The results showed that the C/N ratio decreased during the composting process (reached to 15.6) due to the loss of carbon and the increase in nitrogen content per unit material; also, the NH 4 + /NO 3 ratio decreased with increase in the time of composting and reached