Alarm about wastewater pollution in Vinh City

(Baonghean) - In Vinh City, wastewater pollution occurs in many places due to untreated industrial and domestic wastewater discharged directly into the environment. Faced with this situation, all levels and sectors have taken measures to handle and overcome it. However, this work has only stopped at a few small-scale establishments, without a comprehensive solution, causing serious pollution in reservoirs and river basins in the city.

Untreated wastewater

Research data in recent years shows that industrial wastewater discharged into the environment is about 1,767 m3/day and night, accounting for 37%; medical wastewater also accounts for a significant proportion of the total discharge in Vinh City, with 1,317 m3/day and night, accounting for 27%. Domestic wastewater alone, with a total discharge of about 1,730 m3/day and night, accounts for 36%.

Untreated wastewater discharged into Vinh River causes pollution. Photo: Cong Sang

Currently, there are many scattered enterprises operating in many different industries and occupations in the city, of which mechanical and automobile repair accounts for a large proportion. Most of these establishments have not invested in wastewater treatment systems according to regulations before discharging them into the environment. There are more than 40 establishments that do not meet the environmental wastewater standards according to QCVN 40:2010/BTNMT (National technical regulations on industrial wastewater). Some establishments with polluted wastewater that need attention are Vinh Ford Co., Ltd., Tuan Viet Co., Ltd., Nissan Vinh Co., Ltd., Auto Transport Company and Hong Minh Co., Ltd. In addition, most of the treatment systems of factories and enterprises in industrial clusters in the city are simply tanks, even 2/3 of the industrial clusters have tanks, but they are not in operation. Particularly for Bac Vinh Industrial Park, a large-scale industrial park in Nghe An province, there is still no centralized wastewater treatment plan. Thus, it can be affirmed that wastewater from concentrated industrial areas in the city is only preliminarily treated before being discharged into the outside environment.

In public and non-public medical facilities, although they have invested in wastewater treatment systems, they have not met standards before being discharged into the environment. Wastewater generated from hospitals and medical examination and treatment units has high levels of TSS, BOD5, COD, NH4+, NO3-, PO43-, H2S... toxins. The results of wastewater quality analysis at 22 hospitals and medical centers in Vinh City show that 20/22 facilities have parameters exceeding QCVN 14:2008/BTNMT (data from the project "Investigation and assessment of the current status of wastewater discharge into water sources in Vinh City. Proposing solutions to protect the water environment in the receiving basin" - Department of Science and Technology).

Drainage systems and “overloaded” rivers

Surveys on water quality at Central Lake, Goong Lake, Cua Nam Lake, Thanh Lake, Bay Mau Lake and Vinh Tan Lake show that all lakes are polluted with organic matter and grease. Of which, Thanh Lake is the most seriously polluted, with 6 parameters exceeding QCVN 08:2008/BTNMT level B2 (Surface water standards for waterway transport purposes) from 1.09 to 19.11 times; including parameters COD (amount of oxygen needed to oxidize chemical compounds in water), BOD5 (amount of oxygen needed to oxidize all organic substances), NH4+ (nitrogen hydroxide compounds), PO43- (Phosphate), total grease and Coliforms. Vinh Tan Lake has COD, NH4+ parameters exceeding QCVN 08:2008/BTNMT level B2 from 1.9 to 21.5 times and a very low DO concentration. Bay Mau Lake has NH4+ parameters exceeding QCVN 08:2008/BTNMT level B2 by 27.6 times and is lower than the allowable limit. The remaining lakes including Trung Tam Lake, Goong Lake, and Cua Nam Lake all have parameters exceeding QCVN 08:2008/BTNMT level B2, however, the number of times exceeding the standard is not high (from 1.2 to 3 times).

At the same time, the rivers receiving wastewater in the city, including Vinh River, Ke Gai River and Rao Dung River, all show signs of organic and grease pollution. Of which, the most worrying is the phenomenon of water pollution by Ammonium on all 3 rivers, the most serious is on Rao Dung River; Grease pollution on all 3 rivers is at a high level, the most serious is in the downstream of Ke Gai River. Water quality is differentiated between rivers and between river sections. According to research, the further downstream, the more polluted Vinh River is. On Rao Dung River, there are spatial fluctuations, the head and end of the river can be used for domestic purposes, however, appropriate treatment measures need to be applied, the middle section of the river can only be used for irrigation purposes. The last section of Rao Dung River also shows signs of salinity.

The canals receiving waste in Vinh City are currently heavily polluted, because many parameters do not meet the requirements for quality discharged into water sources. Of particular concern, Coliforms in the wastewater at the Hong Bang canal exceeds QCVN 14:2008/BTNMT (level B) 249 times, the highest among the canals receiving waste in Vinh City. The pollution is also shown through the foul smell coming from the canal sections. Ms. Nguyen Thi Huong - a food vendor on Hong Bang Street said: "Normally, the foul smell coming from the sewer is quite unpleasant, especially on stormy days, it is unbearable. When it rains, the water in the sewer is very dirty...".

Assessing the wastewater reception capacity of the Vinh River, on 7 river sections starting from the upstream of the Vinh River to Ben Thuy wharf. The results of calculating the river's reception capacity show that the Vinh River is no longer able to receive NH4+ and grease. In addition, sections 3 and 5 of the river are no longer able to receive PO43- from 2 waste sources: the drainage ditch of residential area 6A, Cua Nam ward and the drainage ditch southwest of Vinh market. This shows that the level of pollution from the waste sources is very high. The Vinh River section flowing through Le Hong Phong street, although covered with concrete, cannot prevent the stench from the black water source. Mr. Tran Van Hieu - Truong Tien block - Hung Binh ward said: "The water here is very dirty, black and thick with dirty waste, sometimes it cannot flow. We live nearby so it is very uncomfortable sometimes...".

Ke Gai River, on 6 river sections, starting from the upstream to Cho Gia bridge, is no longer able to receive parameters of NH4+ and grease. In addition, at section 2, the river is no longer able to receive PO43- from Dong Vinh canal and at section 4, the river is no longer able to receive BOD from the drainage canal of Mai Loc hamlet, Hung Dong commune. This shows that the pollution level of the waste sources is very high. On Rao Dung River, starting from the upstream of Rao Dung River to Rao Dung bara, it is no longer able to receive parameters of NH4+, PO43-, grease. This shows that the waste sources into Rao Dung River are heavily polluted with organic matter and the water source's ability to receive is very low.

The above summaries show that wastewater pollution from urban areas, industrial zones as well as the inability to receive wastewater from the drainage system, reservoirs and rivers in Vinh City are at a high level. While the pollution level is increasing, the city and its functional sectors have not yet found a solution to handle it. Therefore, the problem is becoming more urgent at an alarming level.

Le Van Hung