Through assessment of surface water quality at Siep stream in Di An city, Binh Duong province. Siep Stream is a level 1 tributary that flows into Dong Nai River. Dong Nai River is currently being exploited and used for domestic water supply purposes. Sampling location of Siep stream at the culvert on National Highway 1K from January 2022 to November 2023, through statistical monitoring data compared with QCVN 08-2023/BTNMT (level A) and QCVN 08: 2015/BTNMT (column A2) - National technical regulation on surface water, it shows that the parameters increase or decrease without stable, most tend to increase with about 86.9% COD exceeding the standard 1.0 ÷ 7.8 times, 95.6% SS parameters exceeding the standard 1.8 ÷ 30.4 times, 95.6% N-NH4 number exceeds the standard of 0.16 ÷ 21.8 times, 52.1% of N-NO2 parameters exceed the standard by 0.52 ÷ 8.9 times, 65.2% of P-PO4 parameters exceed the standard by 0.35 ÷ 6.25 times, 91, 3% of Colifrom parameters exceeded the standard of 1.0 ÷ 3.3 times. The WQI (water quality index) results show that the surface water quality of Siep stream is mostly average, this result is not suitable for domestic water supply purposes, there needs to be solutions to improve water quality at the area Siep Stream.

The present study aims to investigate the possibility of domestic wastewater treatment using biological system combined with chemical-physical processes, including Upflow Sludge Blanket Filtration (USBF) technology and PolyAluminium Chloride (PAC). Experimental results showed that the added PAC content plays an essential role in improving the treatment efficiency and reached National Technical Regulation on domestic wastewater QCVN 14:2008/BTNMT (Column A). With Jar-test results, the optimal pH of 7.0 and the PAC dosage of 170 mg/L were recorded with the highest removal efficiencies for suspended solids and organic matter. In the modified USBF bioreactor, the findings illustrated the pollutant removal efficiencies such as Biochemical Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), and Suspended Solids (SS) were equal to 96.2 ± 1.4%, 85.8 ± 4.4% and 99.3 ± 2.1%, respectively. The parameters of BOD5 and SS met QCVN 14:2008/BTNMT - Column A. In the future, this advanced filtration technology can be helpful for wastewater reclamation and reuse to cope with water scarcity.