Environmental impact of AES project

(Baonghean) - The establishment of Thanh Chuong and Yen Thanh cassava factories in the province has contributed to changing the crop structure and increasing income for thousands of farming households. However, in the process of cassava production and processing, the two factories have caused water and air pollution. Faced with this reality, since 2009, AES Corporation (USA) has built a modern wastewater treatment system that has basically solved the above pollution problem.

Before 2008, the area around the cassava factories in Thanh Chuong and Yen Thanh districts had an unpleasant smell. This fact significantly affected the air and environment for the people in the area. Particularly for the Intimex Thanh Chuong Cassava Starch Factory, in the production process, in addition to the starch obtained for export, the remaining part including cassava peels, cassava residue and wastewater is always a concern for environmental pollution. The factory has solutions such as using cassava peels as biofertilizer to supply farmers at a low price, returning color to the soil. Cassava residue is used as filler for animal feed. As for wastewater, the factory has a system of settling ponds, filters and natural fermentation microorganisms to treat it. However, this method is not thorough, the environment is still affected by the decomposition of remaining starch and protein. Every time it processes cassava, the factory often causes pollution, affecting residential areas, especially the wastewater that causes fish to die in Lam River.

Operators are testing wastewater.

Mr. Tran Quoc Hoan, Director of Thanh Chuong cassava factory, shared: In that situation, in 2008, the factory cooperated with the American AES Group to install a wastewater treatment line using biogas technology with an investment of 2.2 million USD. 100% of the investment cost was invested in construction by this group. By the end of 2009, the modern wastewater treatment line officially came into operation. According to experts, the efficiency of this line is very high. The wastewater treatment process from the factory is brought to the sand settling tank, the equalization tank, the mixing tank, the UASB tank, and then to the biological lake. The wastewater at the cassava factory has reached type B (can raise fish). In addition to wastewater treatment, this system also recovers organic waste from the production process to use as raw materials in the production of high-value microbial organic fertilizers. Every year, the factory produces and processes over 5,000 tons of biofertilizer, enough to serve about 3,000 hectares of raw cassava. In particular, normally, after recovering starch, the product must go through a coal-fired drying system. Now with biogas, the factory has saved about 4 billion VND in this expense each year.

It is known that to ensure thorough handling of environmental issues, in addition to having a wastewater treatment plant, Thanh Chuong Cassava Factory has also invested in 7 settling ponds, including 4 regulating ponds, 2 aeration tanks, 1 monitoring pond, and covering the factory area with trees. The factory has established an Environmental Treatment Team of 8 members with the tasks of operating the wastewater treatment plant system, checking and processing wastewater parameters, adding IEM spraying... Thanks to the implementation of synchronous solutions, the factory has thoroughly handled environmental issues and is operating stably. In the 2014 - 2015 crop year, the factory plans to purchase 120 tons of tubers, process 30,000 tons of starch, with revenue of over 250 billion VND. Mr. Tran Van Ly in Dung Town (Thanh Chuong) said: "Before, every time the production season came, the whole town would smell a foul smell, but in recent years, that phenomenon has not happened anymore, the wastewater has been treated without causing pollution, and people's lives have stabilized again...".

As for the Yen Thanh cassava factory, in 2008 it polluted the water sources along the communes of Cong Thanh, Bao Thanh (Yen Thanh) and some communes of Dien Chau district. At one point, the cassava factory was suspended by the authorities. However, since 2009, after the wastewater treatment plant sponsored by the US AES Group was put into operation, the environmental pollution problem has been well handled. According to a leader of Cong Thanh commune, the environmental pollution caused by the cassava factory before 2008 made the people very dissatisfied, and people continuously protested and filed complaints about the pollution. However, since 2010, the wastewater treatment plant has been put into operation, so the pollution has been basically reduced.

At Yen Thanh Wastewater Treatment Plant, all systems are "automated" and controlled by computers. Mr. Nguyen Van Dong, the wastewater treatment system operator, said: During the cassava production season, we have 2 staff members on duty 24/7. In addition to operating the treatment, we also have to test the wastewater twice a day. If it meets the standards, it can be discharged into the settling pond for further treatment. Mr. Nguyen Vinh Sang - Deputy Director of Yen Thanh Cassava Plant added: Yen Thanh Wastewater Treatment Plant also received an investment of 2.2 million USD from the US AES Group and 2 Vietnamese staff members were directly assigned to operate the treatment. The plant has a campus of over 20,000m2. In addition, to thoroughly handle environmental pollution, Yen Thanh Cassava Factory also invested in a sand settling tank worth 1.5 billion VND, the tank is over 7000 m2 wide and is lined with a tarpaulin bottom according to regulations, to absolutely prevent water from leaking out, this tank is used to wash cassava tubers before being brought into the factory. The factory also invested in 3 more biological reservoirs of 3 hectares to store treated wastewater from the factory. According to Mr. Sang, since using the Wastewater Treatment Plant, it has also brought economic benefits to the factory. Specifically, it used to cost 1.2 billion VND for coal and firewood to dry the powder, now it uses biogas to dry cassava powder.

The problem now is that in our province there are still many private cassava processing sites that cause serious pollution, concentrated in Tan Ky and Nghia Dan districts. It is worth mentioning that although production is "family" style, the capacity of some facilities is quite large, from 8 - 10 tons of cassava tubers/day. During the production process, untreated wastewater is directly discharged into ditches and ditches, causing serious pollution of clean water sources for the people, so a solution is needed to eliminate illegal production sites and return a clean environment to residential areas.

Article and photos:Van Truong