Under the Technical Regulation on Conditions for Discharging Urban and Industrial Wastewater into Surface Water Bodies, the Ministry of Environmental Protection and Agriculture is mandated to identify agglomerations at the river basin or sub-basin level and divide them into two categories based on population equivalent (PE):
- Category A: 2,000 – 10,000 PE
- Category B: More than 10,000 PE
This categorization establishes the level of collection systems and treatment standards required for each agglomeration.
Collection Systems
In the case of wastewater discharge into sensitive areas, a sewage collection system must mandatory be installed for Type B agglomerations. However, if establishing a sewage system involves exceptional technical difficulties and/or disproportionately high costs and is therefore unjustified, individual or other appropriate systems providing the same level of environmental protection must be used.
Where the installation of a sewage system is justified, system design, construction, and technical maintenance must be carried out using Best Available Techniques (BAT). According to environmental protection law, BAT represents the most effective, applicable, and economically viable technology from an environmental perspective to prevent, minimize, or transform environmental impacts. Additionally, construction planning must account for: urban wastewater volumes and characteristics, leakage prevention, and limiting the contamination of collected waters by stormwater overflow.
Secondary Treatment
Following primary treatment, wastewater generated in Type B agglomerations, as well as Type A agglomerations discharging into fresh surface waters and estuaries—transitional areas between fresh and coastal waters—must undergo secondary or equivalent treatment.
Wastewater discharging from a treatment plant must meet the following requirements:
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The design or modernization of the treatment plant must ensure the collection of representative samples of both influent (untreated) and effluent (treated) water prior to discharge. The sampling procedure is governed by the Technical Regulation on "Sanitary Rules for Water Sampling." Sampling points must be defined in the facility's technical design. Seasonal load variations must also be accounted for during plant design.
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Treated Water Standards:
| Parameter | Concentration (mg/L) | Minimum Percentage Reduction of Pollutants | Reference Measurement Method |
| Biochemical Oxygen Demand (BOD₅ at 20ºC)*1 | 25 | 70 – 90% | Homogenized, unfiltered, undecanted sample *2 |
| Chemical Oxygen Demand (COD) | 125 | 75% | Homogenized, unfiltered, undecanted raw sample; Potassium dichromate method |
| Total Suspended Solids 1 |
35 mg/L
(>10,000 PE) |
90%
(>10,000 PE) |
Filter representative sample through a 0.45 µm membrane; dry at 105ºC and weigh |
| Total Suspended Solids 2 |
60 mg/L
(2,000 – 10,000 PE) |
70%
(2,000 – 10,000 PE) |
Centrifuge representative sample (at least 5 min at 2,800 – 3,200 g mean acceleration); dry at 105ºC and weigh |
*1 – This parameter may be replaced by another parameter: Total Organic Carbon (TOC) or Total Oxygen Demand (TOD), provided a correlation can be established between BOD₅ and the substitute parameter.
*2 – Determination of dissolved oxygen before and after a 5-day incubation at 20ºC ± 1ºC in complete darkness, with the addition of a nitrification inhibitor.
Analysis of wastewater discharged from settling ponds/sedimentation tanks must be conducted on filtered samples. However, the concentration of total suspended solids in unfiltered water samples must not exceed 150 mg/L.
Sensitive Areas
Under the regulation, all freshwater surface water bodies—excluding those located above 1,500 meters above sea level—are designated as sensitive areas for urban wastewater discharge. For Type B agglomerations discharging into sensitive areas, more stringent treatment is mandatory, including the removal of nitrogen and/or phosphorus.
| Parameter | Concentration (mg/L) | Minimum Percentage Reduction of Pollutants | Reference Measurement Method |
| Total Phosphorus 1 |
2 mg/L P
(10,000 – 100,000 PE) |
80% | Molecular absorption spectrophotometry |
| Total Phosphorus 2 |
1 mg/L P
(>100,000 PE) |
80% | Molecular absorption spectrophotometry |
| Total Nitrogen 1 |
15 mg/L N
(10,000 – 100,000 PE) |
70 – 80% | Molecular absorption spectrophotometry |
| Total Nitrogen 2 |
10 mg/L N
(>100,000 PE) |
70 – 80% | Molecular absorption spectrophotometry |
Urban wastewater discharge sites must be selected to minimize impact on aquatic ecosystems, water supply facilities, recreational zones, and other sensitive sectors. Treated wastewater must meet secondary treatment requirements prior to discharge into sensitive areas.
Type A agglomerations may also be subjected to these same requirements if it is determined that their discharge negatively impacts sensitive areas. In such cases, the required treatment level is determined by the Ministry.
Less Sensitive Areas and Exceptions
Urban wastewater discharged into Black Sea coastal waters may be subject to less stringent treatment if the receiving environment has sufficient dilution capacity and the discharge will not adversely affect the environment. Similarly, deep-sea discharge of effluent from an urban wastewater treatment plant located in the coastal zone is permitted provided it is confirmed that the receiving water body has sufficient dilution capacity.
In cases where urban wastewater is discharged into water bodies located above 1,500 meters, where effective biological treatment is difficult due to low temperatures, the least stringent standards may be applied.
For the monitoring of urban wastewater, the water user or treatment plant operator must ensure:
- Self-monitoring of treated wastewater at the treatment facility to verify compliance with technical regulation requirements.
- Self-monitoring of both treated wastewater at the treatment plant and urban wastewater discharged directly in high-mountain areas, in cases where a significant negative impact on the receiving environment is expected.
- In sensitive areas, the Ministry must require the water user to conduct monitoring and relevant studies to confirm that the discharge does not cause adverse environmental impacts on parameters such as oxygen content, nutrients, or suspended solids.
