Processes to Treat Wastewater

ITU as a body has a Water Management Directive , which protects water resources on the campus and prevents polluted water from entering the water system. In this way, water systems are not affected by any kind of failure. All infrastructures about stormwater and wastewater are separated from each other.

Sewarage disposal, clean water and rainwater channels in the Ayazağa Campus is shown

The whole generated wastewater is collected from the buildings and conveyed out of the campus. The collected wastewater is received by Baltalimanı Wastewater Treatment Plant which is operated by Istanbul Water and Sewerage Administration. A plan view was given showing the campus and Baltalimanı Wastewater Treatment Plant.

Distance between Ayazağa Campus and Baltalimanı WWTP

The biological wastewater treatment plant (Treated with tertiary treatment), established on an area of 4 hectares, has a capacity of 600,000 m³/day, serving the same population of 2.4 million. In addition, it has a pre-treatment unit with a capacity of 1.3 million m³/day in order to report the flow rate of the room with excessive rainfall.

biologically treated wastewater; It is extended from a depth of -70 m to the horizontal bottom current of the Black Sea of the Bosphorus with 2 deep-sea section pipes of 302 m length and 1600 mm length.

In the facility, biogas will be obtained by decomposing the wastewater sludge formed after the biological treatment process, and electricity and heat energy will be produced by burning gas engines in the cogeneration units of this biogas. In this way, the majority of electricity and heat energy production will be met. In order to obtain biogas from wastewater, 6 Sludge Digester Tanks with a capacity of 10,000 m³, a volume of 42 m and a width of 25 m were built. Egg Section, which has high biogas production efficiency, was used for the first time in Turkey in the construction of sludge digester tanks. The facility leaks approximately 70,000 tons of sludge annually.

All infrastructure about clean water and sewerage disposal pipes are seperated from each other for a future treatment plan in ITU GreenCampus. Currently, the sewerage disposals of university campus are transported directly to the municipality’s Sewerage Treatment Center (ISKI Baltalimanı WWTP) with manholes. ISKI Baltalimanı WWTP now in operation to increase waste treatment level to “advanced treatment” (nutrient recovery etc.)

The work of transforming the Baltalimanı Pre-Treatment Plant, which was put into service by İSKİ in Baltalimanı in 1997, into a Biological Wastewater Treatment Plant is in full swing. Within the scope of the facility, the construction of which started in 2017, the construction works of the pre-treatment units have been completed. The facility, which draws attention with its 6 egg-shaped reinforced concrete Digestion Tanks, applied for the first time in Turkey, produces 44 thousand Nm³ of biogas per day. The Sludge Drying Unit turns the sludge cake with a capacity of 600 tons/day with 25% DM content into the final product with a dry matter content of at least 45% DM.

ITU thrives to build its new additions to the campus sustainably. Therefore, the water is treated according to LEED standards. Two new buildings (Information Technologies and Agro – Informatics Research Center Buildings) on the campus have applications to get a LEED certification and the water use is minimised according to LEED standards.

Consumption of treated water

IFAS-MBR and MBR System

As a result of the decrease in the discharge limits of wastewater treatment plants, many facilities have to be revised to remove nitrogen and phosphorus. Especially in a metropolis like Istanbul, due to problems such as the inability to design a treatment plant due to space problems, it is necessary to achieve high wastewater treatment efficiency by using smaller areas with innovative methods. At this point, it is planned that these treatment facilities will have effects such as reducing waste discharge and preventing marine pollution. It is planned to purify large amounts of wastewater (including nitrogen+phosphorus removal) in small volumes, especially in areas with space problems, by using innovative systems integrated with membrane systems in pilot-scale treatment plants.

The membrane bioreactor (MBR) pilot system is planned to treat and reuse the wastewater with high COD concentration which is coming from a process that grinds the dining hall waste in İTÜ Ayazağa campus. The pilot system, which includes an MBR module with an ultrafiltration level of 100 m2 surface area, has a flow rate of 20 m3 / hour. Effluent water will be used as sprinkler water.

At the same time, as explained in the declaration presented by the Ministry of Environment and Forestry within the scope of Combatting Mucilage, it is aimed to investigate the vision of using membrane systems that will provide wastewater recovery in the modernization of wastewater treatment facilities and to produce scientific results for the designs. It is necessary to take action to prevent water problems and ensure recycling and to transform existing systems into advanced biological treatment systems.

Within the scope of one of the pilot scale systems, two parallel systems, each with a capacity of 500 L/day, were designed and built. The paralel operating systems treat that wastewater comes from ITU Ayazağa Campus.

The systems were fed with real wastewater of the same characterization and the hydraulic feeding was gradually increased. In this way, organic and hydraulic loading rates were determined for each system and the maximum amount of wastewater that could be treated was determined. Since the most discharge into the Marmara Sea is domestic wastewater, the systems will be used for domestic wastewater treatment within the ITU campus. This system can then be used specifically for all kinds of industrial wastewater treatment. Both pilot plants have the same layout. Aerobic reactors were followed by a membrane reactors (MBR). At the end of the treament, pollutant loading rates decreased 90% percent. Effluent charachteristic is approppriete for the usage of irrigation water.

UF ve TO

UF and TO pilot systems with a capacity of 100 m³ / day are located on the Ayazağa campus. These mobile pilot systems can be used for municipalities and private institutions to make preliminary studies and cost calculations in their water recovery projects. Municipalities and private institutions  can install them in the selected treatment plants that want to make preliminary tests for water recovery studies before large scale investment.

Reverse Osmosis 

The permeate water from ultrafiltration is fed to the reverse osmosis system, and the water is subjected to filtration in order to remove the conductivity, total dissolved solids and all other polluting parameters that ion level. There are also replaceable cartridge filters in front of the reverse osmosis unit. System pressures, influent and permeate conductivity values, influent and permeate flow rates are measured online on the line.

There are antiscalant and caustic dosing units in the RO unit. An automatic chemical washing unit is included in the system so that chemical washes can be carried out on site. The permeate water coming out of the UF unit can be used directly as sprinkler irrigation water. RO permeate is of a quality that can feed groundwater or be used as industrial process water. With these pilot plants, the cost of water recovery can be calculated for different alternative usage scenarios.