engleski

Treatment of landfill leachate by membrane processes of nanofiltration and reverse osmosis

The largest portion of solid waste is disposed on or beneath the surface of the earth in so called landfills. One of the major emissions of a landfill is the leachate caused by waste moisture and rain falling onto the surface of a landfill, and percolating through the underlying waste. Landfill leachate is a result of complex hydrodynamic and physico-chemical processes going on within a landfill, and its characteristics and generation rate strongly depend on climate, type of waste, and landfill age. It typically contains a complex mixture of organic and inorganic substances, usually in concentration exceeding maximum concentration levels (MCLs). The aim of this work was treatment of landfill leachate from Jakuševec, Zagreb, Croatia by pressure driven membrane processes of nanofiltration and reverse osmosis (NF/RO). Different types of NF/RO membranes were selected to obtain the parameters of leachate contaminants below MCLS, defined by the Croatian law and EU directive. All experiments were carried out in laboratory set up. As a pretreatment of landfill leachate coagulation were used. In all steps parameters of total carbon (TC), total organic carbon (TOC), inorganic carbon (IC), chemical oxygen demand (COD), pH, turbidity, conductivity, concentration of different ions, heavy metals, etc. were analyzed. COD, TOC, pH, NH4+ of investigated real sample were 1720 mg O L-1, 1260.5 mg C L-1, 8.05, 1147.6 mg L-1, respectively. These results showed that landfill leachate was heavily loaded with organic substances. JAR test showed that 1 g L-1 of Fe3+ ions was optimal dose for coagulation, in pre- treatment step of landfill leachate. COD, TOC and NH4+ were decreased with coagulation for 28%, 58% and 8%, respectively. RO/NF membranes (NF270, NF90 and XLE) additionally decreased COD and TOC for 68% and around 37%, respectively. Ammonium ions were decreased in the range of 34% (NF270) to 81% (XLE). Removal of anions (Cl-, F-, NO2-, NO3-, SO42- and Br-) obtained by coagulation and membrane processes of NF/RO was higher than 80%, i.e. almost all concentration were below MCLS.

Landfill leachate; Coagulation; Nanofiltration; Reverse osmosis; MCLs

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