Less than a week after the new round of ecological and environmental protection supervision group sank, the Ministry of ecological environment announced another batch of typical cases of environmental protection supervision.

From the five typical cases reported in this batch, it can be seen that the problems such as inadequate sewage treatment facilities, sludge treatment and disposal, and obvious defects in the pipe network are still outstanding environmental governance problems at present. One example is that the inspection team found in Hebei that some enterprises in Xingtai, Tangshan, Hengshui and Zaoqiang have long been illegally disposing of sludge, and the problem of sludge dumping at will is more prominent.

Illegal treatment and disposal of sludge frequently occurs, and tricks are constantly performed

Hebei, which is the production and marketing base of sheepskin clothing and leather in China, has a long history of leather industry and occupies an important position in the national leather industry. Behind the prosperity of the leather industry, there are also many typical environmental problems in the enterprises involved in the tanning process.

In this notification, the environmental protection supervision group found that Zhengxiang company in Xingtai City, Hebei Province, illegally received more than 88000 tons of domestic and industrial sludge by signing sludge disposal contracts with 19 units including Xingtai sewage treatment plant and No. 2 sewage treatment plant, on the pretext of raising earthworms. Among them, 6650 tons of industrial sludge were illegally received from Shijiazhuang Juncheng leather company (chrome tanning process). The inspectors found that Zhengxiang company only used a small amount of sludge to cultivate earthworms, and the rest of the sludge was illegally dumped and stacked on the cultivated land, occupying an area of more than 226 mu.

It is not the first time that environmental protection inspectors have reported that "earthworm cultivation" is the illegal dumping of sludge from the head. In August last year, the environmental protection supervision team found in the supervision of Suining City, Sichuan province that xinjingyuan environmental protection company also used earthworm culture as a pretext and directly dumped or buried 105100 tons of sludge in the leased land under the pretext of "soil improvement"* Solid waste network has also reported an illegal dumping case in the name of "earthworm".

From the perspective of reporting the sludge problem in Hebei Province, the illegal dumping in the name of "raising earthworms" is only one of the environmental violations. There are also problems such as tens of thousands of tons of sludge "missing from play" and repeated inspections in the form of "old stick" that are not standardized and rectified.

According to the content of the notice, Tangshan wanong company has gone through the production and operation license and environmental impact assessment approval procedures in the name of using livestock and poultry manure and straw to produce organic fertilizer. Since 2018, it has signed a number of sludge disposal contracts and illegally received 155600 tons of sludge, of which at least 50000 tons of sludge are unknown, and there are serious potential environmental risks.

Daying sewage treatment plant in Zaoqiang County, Hengshui City, as the "old stick" in the notice, appeared again in the notice of the supervision group. As early as 2016, a round of environmental protection inspectors found that a large amount of industrial sludge was piled up around Daying sewage treatment plant in Zaoqiang County, Hengshui City, which was responsible for treating the sewage from the gathering area of fur processing industry (including chrome tanning process). In the rectification plan formulated by Hebei Province, it is clearly pointed out that the reduction solidification technology should be used to dispose the heavy metal chromium in the sludge before sanitary landfill. However, during this inspection, it was found that the problem of illegal disposal of industrial sludge in Daying sewage treatment plant was prominent, and the disposal plan was arbitrarily changed. After illegal landfill in 2016, in July last year, a third party without sludge disposal qualification was entrusted to dispose 2697 tons of industrial sludge, of which nearly 100 tons were transported to Hebei Jinfeng Fertilizer Industry Co., Ltd. as raw materials for organic fertilizer production.

As mentioned above, the ecological and environmental protection inspectors have pointed out the improper treatment and disposal of sludge in many places.

For example, in the second round of the second batch of ecological and environmental protection inspectors, Beijing, Tianjin, Zhejiang and other three provinces and cities were named to have sludge disposal in violation of regulations.

In the second round of three batches of ecological and environmental protection inspectors, Liaoning Chaoyang was pointed out that more than 400000 tons of sludge had been illegally temporarily stored for a long time, and the potential environmental risks were prominent.

In the second round of the fourth batch of ecological and environmental protection inspectors, Suining, Sichuan, was pointed out to have the problem of illegal disposal of sludge, which seriously polluted the surrounding environment.

It can be seen that the sludge problem has become the focus of environmental supervision and treatment, and at the same time, it has also been attached importance by the ecological and environmental protection inspectors. Similarly, from the above cases, it can be seen that the illegal disposal ways of sludge are basically divided into two categories: one is illegal dumping on cultivated land, renting land, etc; The second type is to deliver sludge to enterprises without disposal qualification as production raw materials without authorization.

The illegal treatment and disposal of sludge will bring greater environmental pollution to a large extent. For example, in the relevant cases of Hebei, Hao Haijing, an analyst at the solid waste research center of E20 Research Institute, said: "the chromium containing sludge produced by the tanning and chrome tanning process belongs to hazardous waste (hw21) And shall be properly harmless or resourced under the management of hazardous waste treatment permit. It needs to be clarified again that illegal dumping and disposal of more than three tons of hazardous wastes is a criminal offence. The illegal disposal of domestic sludge and industrial sludge continues despite repeated prohibitions. The main reason is that the sludge disposal capacity is insufficient and the disposal cost is high. Under the high pressure of environmental protection supervision, the production and waste enterprises are driven by interests to take risks. In the face of the repeated occurrence of such problems, in addition to strengthening the construction of the regulatory system and increasing the punishment, it is also necessary to publicize and popularize the environmental hazards and legal consequences of improper sludge disposal, penetrate the cognition from the upstream and downstream of the whole industrial chain, from the decision-making end to the execution end of each link, and eliminate the sense of luck. At the same time, we should strengthen the supplement of sludge disposal capacity, promote the innovation of sludge recycling technology, so as to improve the level of sludge recycling and reduce the cost of sludge disposal. China's hazardous waste treatment industry has entered the stage of refined development. Regulatory departments, waste production enterprises and disposal enterprises should fully consider the full life cycle management of hazardous waste, so as to establish and improve the hazardous waste treatment system and fundamentally eliminate the occurrence of illegal incidents involving hazardous waste. "

ludge, as a by-product of sewage treatment, has always been despised, and the phenomenon of "emphasizing water over mud" is widespread in China. Sludge treatment is "one kilometer after Z" of urban sewage treatment. If it is not properly treated, it will cause secondary pollution to the ecological environment.

Wang Hongchen, Professor of Renmin University, doctoral supervisor, vice president of the school of environment, and director of the low carbon water environment technology research center, once said at the Shanghai water industry hot forum hosted by the E20 environment platform that he had inspected many sewage treatment plants in recent years and clearly felt that a major factor threatening the stable operation of sewage plants was that sludge had no way out.

In this year's National People's Congress, Cheng Hanfei, deputy to the National People's Congress, chief engineer of MCC eco environmental protection group and President of MCC eco environmental protection technology research institute, also pointed out that "the quality of influent water and sludge treatment and disposal are important factors that affect the stable operation of urban sewage treatment plants in China. However, for a long time, there has been a problem of emphasizing water over sludge."

Generally speaking, cost and sludge outlet are two important factors in the process of sludge treatment and disposal.

1. Cost
   
   Previously, Pengpai News reported a case of illegal dumping of sludge in Ningxia. With the in-depth investigation of the police, it was found that this was an organized and planned illegal event. According to the estimation of relevant people, the company could make a net profit of about 1000 yuan per ton after illegally dumping sludge.
   
   Sudden profits have given birth to the grey area of sludge disposal. In addition, the problem of sludge disposal funds is one of the main reasons why enterprises do not hesitate to illegally dispose of sludge at the cost of violating the law.
   
   "At present, the cost of simple dehydration and landfilling of sludge treatment in China is about 100-150 yuan / ton, which is about 0.08-0.15 yuan / ton allocated to the sewage treatment fee. For cost consideration, many of the original sewage treatment plants choose to dehydrate the sludge to 60% and then send it to the landfill. Some places even choose the illegal method of simple dumping." Xue Tao, executive director of E20 Research Institute and part-time professor of Hunan University, recently interviewed * environment news. He said: with the gradual development of relevant laws and regulations, the deterrent effect of ecological and environmental protection inspectors, the shortage of landfill sites, the impact of sludge on the whole landfill site, the huge cost of repairing the sludge yard and other objective reasons, more and more people realized that this simple dry landfill disposal method could not continue and would bring secondary disasters, Therefore, at present, the requirements for sludge disposal have been raised, and the reduction of higher standards has gradually become a universal demand. If the sludge is fully, properly and completely disposed, the cost is about 300 yuan / ton to 500 yuan / ton, and the cost allocated to the sewage treatment fee is about 0.25 yuan / ton to 0.5 yuan / ton. These charges have not been fully adjusted.
   
   The  sludge treatment and disposal market analysis report (version 2020) issued by E20 Research Institute has conducted multi-party research on current domestic sludge treatment and disposal projects (mainly BOT projects). The cost information shown by the research results is as follows: the number of projects with bid winning price of more than 300 yuan for BOT Projects accounts for 56%, and the number of projects with bid winning price of 200-300 yuan accounts for 33%. According to the investigation, the treatment and disposal cost of the overall technical route of sludge anaerobic digestion + biogas utilization + land utilization and aerobic fermentation + land utilization is about 300 yuan, and the dry incineration is relatively high at about 400-500 yuan.
   
   Under the background of * vigorously promoting pollution reduction and carbon reduction, sludge is the enrichment of pollution. About 50% of pollutants in the whole process of sewage treatment are concentrated in sludge, which is the focus of sewage carbon reduction. Under the current "double carbon" target, sludge has become an important grasp for the sewage treatment industry to save energy and reduce consumption, practice carbon peaking and carbon neutralization, and energy resource recycling has become an important direction. The cost of sludge treatment and disposal will also rise to a certain extent.
   
   Therefore, the capital problem is also a problem that needs to be paid attention to in the process of sludge treatment and disposal.

2. Outlet of sludge
   
   Now, the discussion on sludge treatment and disposal technology has been settled. After years of exploration, the sludge treatment and disposal industry in China has mainly formed four mainstream technical routes of stabilization treatment and full disposal of an: "anaerobic digestion + land utilization", "aerobic fermentation + land utilization", "drying incineration + ash landfill or building materials utilization", and "deep dehydration + emergency landfill", which support the solution of sludge treatment and disposal problems in China. With the upgrading and reconstruction of the sewage treatment plant, the sludge disposal has extended the path of coupling garbage incineration, cement kiln collaborative disposal, and soil remediation, and the technical process has broken through the bottleneck.
   
   E20 Research Institute has pointed out that during the "12th Five Year Plan" period, the main route is to enter the landfill after sludge drying (deep dehydration), and the service cost is relatively low. However, it also brings the risk of resource waste and hidden dangers of the landfill. In the "13th five year plan" period, environmental protection issues have become more and more systematic, and the policies of solid waste and water have become more and more strongly related. The implementation plan of domestic waste short board issued by the national development and Reform Commission, the Ministry of housing and urban rural development and the Ministry of ecological environment has made extensive restrictions on new urban landfills, which has become a scarce resource, thus further closing the route of simple drying landfill disposal of sludge.
   
   In the Hebei Province notified this time, because in October 2021, the Department of housing and urban rural development of Hebei Province issued the notice on accelerating the closure and deactivation of landfills in the areas covered by domestic waste incineration and treatment facilities (hereinafter referred to as the notice), requiring that the closed and deactivated domestic waste landfills in the areas covered by the domestic waste incineration and treatment facilities that have been put into operation will no longer receive the task of harmless treatment of domestic waste.
   
   Therefore, sludge treatment and disposal routes such as "anaerobic digestion + land use", "aerobic fermentation + land use", "drying incineration + ash landfill or building materials utilization" have attracted more and more attention. This further suggests that one of the key issues of sludge treatment and disposal, "where will the sludge go?" has become a difficult problem to be faced.