Norit X-Flow technology underpins advanced membrane leachate plant in Turkey
Two years ago, ISTAÇ (Istanbul Metropolitan Municipality Environmental Protection and Waste Materials Valuation Industry) and Norit X-Flow embarked on a one-of-its-kind wastewater treatment project - the treatment of leachate from the Istanbul landfill in Odayeri and Kömürcüoda. Jürgen von Hollen, Managing Director of Norit X-Flow pointed out that the ISTAÇ Leachate Treatment project represented one of the most challenging filtration projects globally based on its size, environmental conditions and continuous growth rates.
After nearly two years of operation and treating up to 3,500 m3/day of landfill water percolate, the conclusion is that the plant meets its specifications and contractual requirements for discharge of the treated effluent. The installation is being touted by Norit X-Flow as the largest membrane leachate plant in the world, involving the most advanced water treatment technology available. ISTAÇ and Norit X-Flow celebrated the official handover on 17th August 2010.
Water percolating through landfills for solid waste results in leachate, which may contain undesirable or toxic chemicals. The ISTAÇ landfill is constructed to prevent leachate contamination of groundwater or surface waters. The landfill percolate containing high amounts of COD, BOD, TSS and Nitrogen is collected and treated by Norit's Membrane Bioreactor (MBR) technology, which makes it possible to discharge this water directly into the Black Sea, in line with both current and future drainage standards.
Apart from the MBR technology, the wastewater treatment plant uses a combination of two advanced Norit X-Flow technologies: a biological process, applied in conjunction with ultrafiltration followed by nanofiltration.
The collected leachate is first subjected to primary clarification and thereafter, transferred to a bioreactor unit for biological treatment. In the bioreactor, COD, BOD and Nitrogen compounds are eliminated. Subsequently, the Norit X-Flow Crossflow membrane system, placed outside of the bioreactor, separates sludge and solid waste on suspension and some amount of COD. Lastly, the Norit NF installation eliminates the remaining COD, organic micro polluters, heavy metals and other compounds (humic acids, colour), resulting in the effluent water quality conforming to current and future discharge standards.
Akguel, Managing Director of ISTAÇ added that the success of the project beyond the technological solution can be attributed to the project partnership approach adopted by ISTAÇ and Norit X-Flow at both the operational and the management levels, in order to ensure full commitment and prioritisation for the project.
Leachate treatment project
ISTAÇ stores daily 14,000 tonnes of municipal solid waste around Istanbul at the municipal solid waste landfill area. The amount of leachate discharged from these wastes is 3,600 m3/day. At Kemerburgaz/Odayeri Landfill Area, infiltration water amount is 2,400 m3/day and at Şile/Kömürcüoda Landfill Area it is 1,200 m3/day.
Treatment plants are composed of pre-clarifier, MBR (nitrification de-nitrification UF membranes), nanofiltration units and sludge dewatering units. Plants are designed to be compatible with discharge to channel at Odayeri Sanitary Landfill Area and with stream discharge standards at Kömürcüoda Sanitary Landfill Area.
Leachate from landfill area is subjected to clarification process and some amount of TSS, COD, and hardness is eliminated. After clarification, the leachate is first transferred to a bioreactor Unit. In the aerobic side, the COD is converted into CO2, while sludge with oxygen and organic nitrogen is converted into NH3 with the help of oxygen. When there is sufficient oxygen, ammonium is converted into NO2 and NO3. In anaerobic unit, NO2 and NO3 is converted into NO2, CO2 and sludge via BOI.
Physical treatment
After biological treatment, the leachate is transferred to the membrane system. The membrane system is composed of two phases. The first phase is the ultrafiltration (UF) that enables sludge separation at the output water. During this phase, the suspended solid material is eliminated. The concentrated part, obtained with UF, is returned to bioreactor. The output water is sent to nanofiltration unit. The UF system is composed of tube membranes located outside the bioreactor with cross-flow system, which prevents blocking and allows high flow passage.
The second phase is the nanofiltration unit, which eliminates a major part of the remaining COD, organic micro polluters, heavy metals and other compounds (humic acid, colour). The nanofiltration system is composed of capillary membranes that leave only low concentrate (less than 10%). The output water is discharged after nanofiltration.
© H2O 2010
