Lack of national standard air drying tanks: such sewage treatment projects are running naked

Due to the lack of national standards and specifications for air drying ponds, coupled with insufficient technical preparation, this sewage treatment project commonly used in the northwest region of China has many problems.The drying pond, also known as the evaporation pond, is a type of concentrated salt water treatment facility

Due to the lack of national standards and specifications for air drying ponds, coupled with insufficient technical preparation, this sewage treatment project commonly used in the northwest region of China has many problems.

The drying pond, also known as the evaporation pond, is a type of concentrated salt water treatment facility. The principle is to store the remaining non recyclable concentrated salt water after treatment in a water tank that has undergone anti-seepage treatment, and evaporate it through natural drying. The remaining waste salt after evaporation is buried or reused. This process is widely used in industries such as chemical engineering and smelting, especially in the coal chemical industry.

In 2015, the original Ministry of Environmental Protection listed the supervision of environmental pollution in Tengger Desert, involving the issue of drying ponds.

The Ministry of Ecology and Environment introduced that when approving the environmental impact assessment of related construction projects, it is strengthening the requirements for the treatment of concentrated salt water and miscellaneous salt, and strictly controlling the setting of drying ponds. In areas lacking polluted water bodies, evaporation ponds, drying ponds, oxidation ponds, and temporary storage ponds should also prevent pollution of groundwater.

The drying pool on "Da Chai Dan"

There is a place on the northern edge of the Qaidam Basin in Qinghai called "Da Chaidan", which means "Da Yanze". The proven reserves of mineral resources here have a potential economic value of up to 5.7 trillion yuan, accounting for more than a quarter of the total potential economic value of minerals in Qinghai Province.

In the 1950s and 1960s, Dachaidan became the main battlefield for the development and construction of the Qaidam Basin. As of now, three industrial concentration areas have been established, including Xitieshan, Yinmaxia, and Chaidan, with 47 various industrial enterprises.

The rapid increase in the number of enterprises and expansion of production capacity not only bring in billions of yuan of GDP per year, but also add countless drying ponds on the boundless Gobi Desert, becoming one of the main pollution sources in the local area.

From July 14 to August 14, 2019, the Sixth Central Ecological and Environmental Protection Supervision Group conducted the second round of central ecological and environmental protection supervision in Qinghai Province. Dachaidan Hexin Technology Co., Ltd. (hereinafter referred to as "Hexin Technology") and Dachaidan Leqing Technology Chemical Co., Ltd. (hereinafter referred to as "Leqing Technology"), two enterprises, were required to rectify due to their failure to treat wastewater in accordance with the requirements of the environmental assessment approval, and a large amount of high concentration production wastewater was directly discharged into the drying tank for evaporation, highlighting environmental hazards.

On the afternoon of October 11th, a reporter from First Financial found the production plant and drying pool of Hexin Technology on the Gobi Desert, which is more than an hour's drive from Chaidan Town. According to Tianyancha data, Hexin Technology was established in 2014 and is mainly engaged in the manufacturing of chemical raw materials and chemical products. The registered capital of the enterprise is RMB 50 million.

From satellite images, it can be clearly seen that there are multiple black or brown patches of varying sizes on the south and southwest sides of the Hexin Technology factory area, with a total area exceeding that of the factory area. There are also 8 black or brown patches of varying sizes on the northeast side of the Leqing Technology production plant area, approximately 20 kilometers away in a straight line, with a total area equivalent to that of the plant area.

These patches are all drying pools, "a local environmental volunteer told a reporter from First Financial. The image materials he provided to the reporter showed that on July 2 this year, technical personnel from the Shanghai Pudong Yixing Biodiversity Research Center had taken samples from the drying ponds of these two enterprises.

Shortly thereafter, the testing reports provided by Tianjin Shipu Testing Technology Service Co., Ltd. and Beijing Beida Zhihui Microstructure Analysis and Testing Center respectively showed that the pH values of the wastewater sampled from the drying tanks of both enterprises showed strong acidity. Compared with the first level standard limit values in Table 4 of the "Comprehensive Wastewater Discharge Standard GB8979-1996", the indicators of wastewater chromaticity, chemical oxygen demand, ammonia nitrogen, etc. in the drying pond are thousands of times higher than the standard limit values.

Based on existing evidence and combined with on-site sample testing results, it can be determined that the wastewater discharged into the drying pond by the two enterprises has not undergone any environmental protection measures or pre-treatment procedures, and is directly discharged into the drying pond. The drying pond is the final discharge site of its production wastewater, "a technician from the Shanghai Pudong Yixing Biodiversity Research Center told reporters.

According to the data, Hexin Technology completed the first phase of a project in 2016 with an annual production of 5000 tons of sodium hydroxide and 4000 tons of potassium hydroxide. The project was put into operation in October 2017 and underwent environmental acceptance in July 2019; In May 2015, Leqing Technology began construction of a 10000 ton/year production project for acid acid and 3000 ton/year acid dye intermediates. In June 2016, the first phase of a 6000 ton/year automatic production line for acid was completed. In March 2019, the environmental acceptance opinions and public announcement results of the project were filed.

Outstanding environmental hazards in the drying pool

And in the central environmental inspection of that year (2019), both companies were named.

According to the report released on July 25, 2019 by the Dachaidan Industrial and Commercial Bank of China on the handling of the issue of "illegal behavior of Dachaidan Hexin Technology Co., Ltd. and Dachaidan Leqing Technology and Chemical Co., Ltd." by the Central Sixth Ecological Environment Protection Supervision Group's petition report (hereinafter referred to as the "Report"), on July 23, a petition report was received from the Central Sixth Ecological Environment Protection Supervision Group. On the 24th, on-site verification was conducted and rectification requirements were clearly proposed.

The report states that Hexin Technology "has problems with some batch constructions not being in compliance, production wastewater treatment facilities not operating properly, and boiler nitrogen oxide emissions not meeting standards"; Leqing Technology's report on solid waste is partially true. According to the report, the production wastewater of Leqing Technology is treated by the process of acid-base neutralization+extraction+MVR+spray oxidation+solar evaporation tank. During the on-site inspection, the production wastewater treatment facilities were in normal operation, and the six solar ponds after the production wastewater treatment naturally evaporated. 70-80% of the treated distilled water is reused in the production process.

However, a field investigation by personnel from the Shanghai Pudong Yixing Biodiversity Research Center found that the anti-seepage structures of the drying ponds of the two companies mentioned above were not constructed and implemented in accordance with the national "Pollution Control Standards for Hazardous Waste Landfill". For example, only a single worker composite lining was used for anti-seepage, and its anti-seepage film thickness was only 1.0mm. However, the national standard requires a double worker composite lining, and the anti-seepage film thickness is not less than 2.0mm.

On May 9, 2020, the Central Environmental Protection Inspection Group provided feedback on the inspection opinions to Qinghai Province. The inspector's opinion clearly stated that "Da Chaidan Circular Economy Industrial Park and Xin Technology Co., Ltd. and Leqing Technology Chemical Co., Ltd. did not treat wastewater in accordance with the requirements of the environmental impact assessment approval, and a large amount of high concentration production wastewater was directly discharged into the drying tank for evaporation, highlighting environmental hazards

The "Rectification Plan for the Feedback of the Second Round of Central Ecological Environment Protection Inspectorate in Qinghai Province" released in October 2020 requires "strengthening the daily environmental supervision of industrial park enterprises to ensure that pollutants are discharged up to standard".

The rectification plan requires Haixi Prefecture to investigate and punish the environmental violations of Hexin Technology Co., Ltd. and Leqing Technology Chemical Co., Ltd. that did not treat wastewater in accordance with the requirements of the environmental impact assessment approval (the rectification time limit is to carry out legislative reforms); The Chaidamu Circular Economy Pilot Zone urges Hexin Technology Co., Ltd. and Leqing Technology Chemical Co., Ltd. to strictly follow the environmental impact assessment approval for wastewater treatment, and achieve the emission of waste gas and wastewater up to standard (the rectification deadline is the end of December 2021).

However, according to a WeChat article titled "The Ecological Environment Bureau of Haixi Prefecture" titled "The Ecological Environment Bureau of Dachaidan Municipal Committee Actively Implements Central Environmental Protection Supervision and Rectification to Effectively Promote Ecological Environment Governance" (June 1, 2022), it was revealed that based on the progress of rectification by Hexin and Leqing enterprises, more than 50% of wastewater reuse rate has been achieved in 2021, greatly reducing COD emissions. However, according to the rectification plan issued by the provincial party committee and government, by the end of 2021, emissions have reached the standard (i.e. achieving 100% reuse and zero emissions), and it has now exceeded the deadline. The enterprise's rectification projects still need to be continuously tested and upgraded in stages, and it is still difficult to complete the target tasks this year (2022).

National standards and norms have not yet been introduced

During an interview, a reporter from First Financial learned that there are multiple enterprises in the Qaidam region that have problems with the evaporation treatment of production wastewater by drying ponds. The Central Sixth Ecological and Environmental Protection Inspection Group stated in the above-mentioned inspection opinions that four soda ash production enterprises, including Qinghai Fatou Alkali Industry Company, in the Chaidamu Circular Economy Experimental Zone, have not fully utilized their water resources. They have long discharged ammonia waste liquid into drying ponds for evaporation treatment, resulting in an annual discharge of up to 30 million tons.

The above "Rectification Plan for the Feedback of the Second Round of Central Ecological Environment Protection Supervision in Qinghai Province" states that we will accelerate the completion of the demonstration project for comprehensive recycling and utilization of ammonia waste liquid, systematically summarize and comprehensively promote the technology for comprehensive recycling and utilization of ammonia waste liquid supernatant, ensure the completion of water resource recycling indicators, and effectively reduce the discharge of ammonia waste liquid.

Enterprises use air drying ponds as the final discharge site for their production wastewater, and evaporation ponds are not built according to hazardous waste standards, which can easily cause wastewater leakage and serious pollution to the soil and groundwater environment in relevant areas. "Environmental protection lawyer Wang Wenyong told reporters from First Financial.

So, does the drying tank process allow untreated or untreated sewage to be discharged into the drying treatment? According to the official website of the Ministry of Ecology and Environment, "Selected Letter from the Minister's mailbox", "Reply on Some Issues Concerning the Drying Pool Technology" (October 31, 2018), in areas lacking sewage receiving water bodies, modern coal chemical projects should be constructed, and effective treatment measures should be taken for high salinity wastewater to prevent pollution of groundwater, atmosphere, soil, etc; The selection of evaporation ponds, drying ponds, oxidation ponds, and temporary storage ponds, as well as groundwater seepage prevention and monitoring measures, should also refer to the "Pollution Control Standards for Hazardous Waste Landfill" (GB18598) to prevent groundwater pollution.

At present, the ecological and environmental authorities have strengthened the requirements for the quality treatment of concentrated salt water and miscellaneous salt when approving the environmental impact assessment of related construction projects, and strictly controlled the setting of drying ponds. The response stated that the construction of drying ponds should determine whether there is any illegal behavior in the inflow water quality of drying ponds according to the requirements of the environmental impact assessment approval. At the same time, if the air drying pond is used as the final discharge route, it involves the discharge of pollutants in a way that evades regulation.

The reply stated that currently, there are no corresponding standards and specifications for the drying ponds in sewage treatment projects at the national level. Some places have introduced local standards and specifications. For example, the "Guidelines for the Prevention and Control of High Saline Water Pollution in Inner Mongolia Autonomous Region" requires that the total dissolved solid concentration of high saline water discharged into the drying tank should not be less than 1000mg/L, and other indicators should meet the first level standard limit in the "Comprehensive Wastewater Discharge Standard" (GB8978-1996). In addition, in practical operations, there are also agreements and standards signed between enterprises and operating units for the discharge of high salt water into drying ponds.

Although there are no national standards and regulations for air drying ponds, the country has clear and strict requirements for sewage discharged into air drying ponds, which is not impossible to follow. In reality, this is also the case, "said Wang Wenyong.

The Ministry of Ecology and Environment also stated in the above reply that if the drying pond is constructed in accordance with the requirements of the environmental impact assessment approval, and the water accumulation situation also meets the requirements of the environmental impact assessment approval, it should not be considered as a violation of pollution discharge by the enterprise. If excessive wastewater is discharged into the external environment through a drying tank, it should be deemed as illegal discharge by the enterprise.

According to a reporter from First Financial, in response to the difficulties encountered by enterprises such as Hexin Technology and Leqing Technology in evaporating and treating drying ponds, the Haixi Prefecture Ecological Environment Bureau has stated that it will help enterprises to do a good job in connecting with the park's sewage treatment plant, explore the feasibility of discharging the remaining reclaimed water into the park's sewage treatment plant, and solve the final problem of 100% reuse. At the same time, enterprises are required to ensure the stable operation of wastewater treatment plants, collect relevant information, conduct production process data statistics, and entrust third-party institutions to conduct comprehensive wastewater treatment and recycling demonstration.

Column Editor in Chief: Qin Hong Text Editor: Yang Rong Inscription Source: Visual China Image Editor: Cao Liyuan

Source: Author: First Financial

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