Abstract
In order to evaluate the quality of effluent pollutants from the rainbow trout breeding farms in the selected farms of Kohgiluyeh and Boyer Ahmad, West Azarbayjan and Mazandaran provinces, water samples were taken from 5 individual selected farms of each province, during 2022. The physical and chemical indicators of water were measured once in each season from the inlet and outlet water (one treatment with 3 replicates).
According to the results, in the selected farms of Kohgiluyeh and Boyer Ahmad province, the changes in water temperature (3.0-21.0°C), air temparature (5.0-26.0°C), the range of pH changes (6.7-8.23), BOD5 (6.00-7.06 mg/L), COD (0.00-6.00 mg/L), TSS (12-585 mg/L), ammonium (0.57 mg/L), nitrite (0.00-0/181 mg/L), nitrate (2.19-19.2 mg/L), phosphate (0.01-0.38 mg/L), DO (6.12-8.11 mg/L) and fecal coliform count (4-897/CFU) was obtained.
In selected farms of West Azarbaijan province, according to the results, the range of changes in water temperature (4.0-22.0°C), air temperature (3.00-27.00°C), DO (6.24-9.16 mg/L), BOD5 (0.00-5.00 mg/L), COD (3.00-27.00 mg/L), TSS (1-685 mg/L), pH (7.15-8.52), phosphate (0.0-0.32 mg/L), ammonium (0.002-0.9 mg/L), nitrite (0.002-0.389 mg/L), nitrate (1.22-22.7mg/L), the number of faecal coliform was 1.6-5.7 (MPN/100ml).
In the selected farms of Mazandaran province, according to the results, the range of changes in water temperature (3.0-24.0°C), air temperature (2.0-25.00°C), DO (6.16-9.24 mg/L), BOD5 (0.24-2.76 mg/L), COD (2.4-93.4 mg/L), TSS (2-288 mg/L), pH (7.44-8.62), phosphate (0.01-206 mg/L), ammonium (0.012-0.538 mg/L), nitrite (0.001-0.426 mg/L), nitrate (0.10-18.11 mg/L), faecal coliform count (9-1000 CFU).
General conclusion In the selected trout farms of the studied provinces, TDS in some aquaculture farms was higher than the effluent standard. The comparison of the average phosphorus content of effluents and farm inputs with the EPA limit showed a significant difference. The amounts of faecal coliform of the farms were in the higher range than the declared limit based on the proposed standard for disposal of waste water to return water to surface water. (WHO and EPA). Other measured indicators were within the range of EPA, WHO and Iranian environment standards. So it can be said that the values of the water quality index are in the range of 62-91, which indicates the relatively good quality of the water entering and leaving the fish breeding workshops. In general, the average and water quality index (IRWQI) was obtained (0.0-91.62). In total, the input and output stations indicate that the water of these fish breeding farms did not cause environmental problems and pollution for the downstream water. A very important point in summarizing this report is the average release of total nitrogen and phosphorus factors for each ton of salmon production in these three provinces, 244.4±9.6 and 190.4±5.6 kilograms, respectively.
Keywords: Rainbow trout, Effluent, Mazandaran, Kohgiluyeh and Boyer Ahmad, West Azarbayjan,