Turkish Regulations...

Turkish Regulations for Design of Sewers...

According to Directions No.3, one of the regulations of Iller Bank which is responsible for the infrastructure systems in Türkiye, hydraulic design of the sewer systems must be met the following criteria.

Design Flowrate...

First step is to calculate Flowrate of Potable Water Distributed to City using the following equation.

"Potable Water Flowrate"...

Second step belongs to calculation of Wastewater Flowrate via the following relationship.

"Wastewater Flowrate"...

The last step is involved with calculation of Unit Wastewater Flowrate using the following equation.

"Unit Flowrate"...

Hydraulic Design Equation...

Currently, the Manning equation is used most commonly for the design of sanitary sewers. The recommended n value for the design is 0.015.

"Manning Equation"...

Sewer Pipe Materials and Sizes...

The principal materials used in the manufacture of sewer pipe are asbestos cement, ductile iron, reinforced concrete, prestressed concrete, PVC, and vitrified clay. In Türkiye, prestressed concrete is being used. Minimum sewer sizes are usually specified in local building codes. The smallest sewer used should be larger than the building sewer connections so that objects passed through the building sewer will not clog the municipal sewer.

According to Directions No.3 of Iller Bank, minimum size of building sewer connections and gravity sewers must be 150 mm and 200 mm, respectively.

Minimum and Maximum Velocities...

When the velocity of flow in a sewer is low, there is a tendency for the solids present in wastewater to settle out. The minimum velocity must be equal or higher than 0.50 m/sec. To avoid damaging sewers it is recommended that the maximum flow velocities be limited to values equal to or less than 3.00 m/sec.

Minimum and Maximum Slopes...

Minimum slopes are often used to avoid extensive excavation where the slope of the ground surface is flat. Maximum slopes are generally applied in case of falling. According to Directions No.3, minimum and maximum slopes should be determined by the following criteria.

"Min. & Max. Slopes"...

Construction of Sewers...

There are many ways in which the actual construction of a sewer system may be accomplished, depending on the soil conditions encountered and the construction equipment available for the job. The important thing is that the finished sewer perform the function for which it is intended with a minimum of maintenance cost. To attain this and, three conditions should be met.

• The pipe should be handled carefully, properly bedded, and backfilled in such a manner that there is a minimum of breakage during and after construction
• Joints should be made with sufficient care to eliminate excessive infiltration
• The line and slope of the sewer should be free of irregularities that might favor the accumulation of solid wastes with resultant clogging of the pipe

"Sewer Ditch"...

Sampling and Flow Measurement Directions Stated on Turkish Water Pollution Control Regulation...

• Parameters not listed on the directions of Institute of Turkish Standards must be analyzed according to Standard Methods
• Flow measurement must be carried out by direct measurement or velocity - area measurement
• On using of direct measurement method, California pipe, nozzle, magnetic flowmeter, orifice, venturimeter, trace material and weir are applicable
• On using of velocity - area measurement method, propeller, anemometer, float, pitot tube, and trace material are applicable
• For small units producing wastewater, if the measurement is not possible, declaration of the unit can be considered
• Depth and flowrate measurements of the rivers are done by Turkish Water Works and Turkish Electricity Works
• Frequency of flow measurement and sampling are directly related to flowrate

"Frequency of Flow Measurement & Sampling"...

• Samples must be taken on the basis of 2-h or 24-h composited samples
• Parameters to be analyzed are given on Turkish Water Pollution Control Regulation on the basis of industrial sectors (an example is shown below)

"An Example for Receiving Media Discharge Standards"...

• Sample must be having enough volume for analysis of related parameters
• Sample must be preserved and transported appropriately
• Sample containers must be selected on the basis of wastewater characteristics
• Sample container must be having a sticker on which name of the sampler, date and time, location, wastewater temperature, volume, depth, and ambient air conditions were written
• Sample container must be precleaned appropriately
• Before sampling, container must be half-filled, shaked and emptied 3 times by wastewater to be collected
• Warm samples must be cooled at the laboratory
• Sampling programme must be in accordance with TS 5089
• In case of large fluctuations on wastewater flowrate, frequency for composited samples must be between 5 and 60 minutes
• Dissolved gases, residual chlorine, sulphide, temperature, and pH must be measured on sampling location
• If a preserver would be used, it must be added into container before collection
• Results of analysis must be recorded and saved for 3 years
• Sampling procedure must be in accordance with TS 5090
• Preserving procedure must be in accordance with TS 5106
• Surface waters must be categorized on the basis of colors

"Categorization of Surface Waters"...

• Ground waters must be categorized on the basis of YAS I, YAS II, and YAS III
• If sea - outfall (with pretreatment) is being used instead of full-treatment, sea-sample must be taken into a circle of which diameter is 1 km and center is center of diffuser
• In case of strong current, sample can be taken from a different location

Turkish Discharge Standars...

Turkish Water Pollution Control Regulation...

According to The Environment Law (Public Law 2872) became active on August 9, 1983, The Turkish Goverment established The Water Pollution Control Regulation which declares standards for wastewater discharges, on September 4, 1988. Current standards require that as a minimum all municipal wastewater be treated to secondary standards shown below. Secondary treatment of municipal wastewater is generally assumed to include settling, biological treatment, and disinfection, along with sludge treatment and disposal. Thus, the principal components of municipal wastewater, suspended solids, biodegradable material, and pathogens should be reduced to acceptable levels through secondary treatment.

"Receiving Media Discharge Standards for Municipal Wastewater"...

The Turkish regulations define receiving streams as either effluent - limited or water quality - limited. An effluent - limited stream is a stream which will meet its in - stream standards if all discharges to that stream meet the secondary - treatment and best - available - technology standards. Municipalities and industries discharging to effluent-limited streams are assigned discharge permits under the regulations. Water quality - limited standards (Turkish Regulation) for sea - side used for recreational purposes, were shown below.

"Discharge Standards for Recreational Areas"...

A water quality - limited - stream would not meet its proposed in - stream standards even if all discharges met secondary - treatment and best - available - technology criteria. Discharges to these streams may be required to meet effluent conditions more stringent than secondary - treatment and best - available - technology.

Effluent standards, potable - water standards, and in - stream standards are obviously interrelated. Enforcement of effluent standards, along with the control of nonpoint sources of pollution, should result in the attainment of in - stream standards. The improvement of in - stream quality should result in a better raw water for potable supplies. However, it is impractical to expect surface waters, even if in - stream standards are met, to meet all of the maximum contaminant levels imposed by the potable - water standards. Treatment of surface water for potable use will always be required, the nature and level of treatment depending on the in - stream quality of the water source.

"IZSU" Wastewater Discharge Regulation...

"IZSU", General Directorate of Water and Sewer Systems of Metropolitan City of Izmir, was built on December 4, 1991 to establish standards related to municipal and industrial discharges into metropolitan sewer system and to control them.

More stringent standards may be imposed where necessary, and in some cases less stringent standards may be permitted for small flows. Industrial discharges are required to treat their wastewater to the level obtainable by the best - available - technology for wastewater treatment in that particular type of industry. If industry discharges to a municipal wastewater collection system, the industrial waste must be pretreated so as to be compatible with the untreated municipal wastewater. Discharge standards for municipal sewer system of Metropolitan City of Izmir are shown below.

"Discharge Standards for Municipal Sewer System of IZSU"...

If industry does not meet the aforementioned discharge standards, it is charged by "IZSU" via following equation called Share for Pollution Prevention.

"Share for Pollution Prevention"...

Turkish Regulations for the Reuse and Disposal of Sludge...

According to The Environment Law (Public Law 2872) became active on August 9, 1983, The Turkish Goverment established The Solid Waste Pollution Control Regulation which declares standards for collection, transportion, and ultimate disposal of solid wastes, on March 14, 1991. Regulations related to wastewater treatment sludges are given below.

• Maximum water content of the sludges being filled into the municipal landfills must be 65 %
• Manager of the landfill can accept treatment sludge having a water content of 75 % into the landfill, deciding that constructual stability of the landfill will not be adversely affected by relatively high water content of the sludge and odor will not create any problem
• Quantity and quality of leachate must be regulary monitored by the landfill management and the results must be sent to the Ministry of Environment, Permanent Undersecretary
• Leachate analysis must be continued for 10 years after the landfill is closed
• Sludge originated from the domestic wastewater treatment plant can be incinerated if the content of fixed organic chlorine is lower than 1 % by weight or the content of halogenated organics is lower than 0.005 % by weight
• If sludge originated from the domestic wastewater treatment plant will be reused for agricultural purposes, analysis for heavy metals such as lead, cadmium, chromium, copper, nickel, zinc, and mercury and nutritious elements such as nitrogen, phosphorus, potassium, calsium, and magnesium must be conducted every 6 months and the results must be sent to the governor or mayor
• Before the application, pH value of the soil must be determined with respect to heavy metals
• During the land application, heavy metal analysis must be carried out regularly
• Results must be given to agricultural land owner
• Raw sludge which is epidemically unsuitable can not be agriculturally used
• If the heavy metal content of soil exceeds the standard values shown below, the application must be ended


"Maximum Heavy Metal Content of the Soil"...

• Maximum annually application rates of the heavy metals are shown below


"Maximum Annually Application Rates"...

• The governor or the mayor may increase the standards shown below by getting permission from the government


"Maximum Heavy Metal Content of the Sludge"...