Emergency Drinking Water Treatment during Source Water Pollution

Dec 6, 2010 - Department of Environmental Science and Engineering, Tsinghua University, Beijing, China 100084, and Department of Environmental Science...
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Environ. Sci. Technol. 2011, 45, 161–167

Emergency Drinking Water Treatment during Source Water Pollution Accidents in China: Origin Analysis, Framework and Technologies† X I A O - J I A N Z H A N G , ‡ C H A O C H E N , * ,‡ PENG-FEI LIN,‡ AI-XIN HOU,§ ZHANG-BIN NIU,| AND JUN WANG‡ Department of Environmental Science and Engineering, Tsinghua University, Beijing, China 100084, and Department of Environmental Sciences, School of Coast and Environment, Louisiana State University, Baton Rouge, Louisiana 70803, United States, and Urban-Rural Planning Center, Ministry of Housing and Urban-Rural Construction, Beijing, China 100065

Received June 11, 2010. Revised manuscript received November 12, 2010. Accepted November 15, 2010.

China has suffered frequent source water contamination accidents in the past decade, which has resulted in severe consequences to the water supply of millions of residents. The origins of typical cases of contamination are discussed in this paper as well as the emergency response to these accidents. In general, excessive pursuit of rapid industrialization and the unreasonable location of factories are responsible for the increasing frequency of accidental pollution events. Moreover, insufficient attention to environmental protection and rudimentary emergency response capability has exacerbated the consequences of such accidents. These environmental accidents triggered or accelerated the promulgation of stricter environmental protection policy and the shift from economic development mode to a more sustainable direction, which should be regarded as the turning point of environmental protection in China. To guarantee water security, China is trying to establish a rapid and effective emergency response framework, build up the capability of early accident detection, and develop efficient technologies to remove contaminants from water.

Introduction China has been experiencing rapid industrialization and economic development over the past 30 years; however, this has been associated with a high cost to the environment, including frequent water pollution accidents (1, 2). According to the former State Environmental Protection Administration (SEPA, now Ministry of Environmental Protection, MOEP), there were 6677 water pollution accidents from 2000 to 2008 (3, 4), many of which threatened the safety of water sources (Table 1). Among these, the Nitrobenzene Spill in the Songhua † This manuscript is part of the Environmental Policy: Past, Present, and Future Special Issue. * Corresponding author phone: +86-10-62781779; fax: +86-1062781779; e-mail: [email protected]. ‡ Tsinghua University. § Louisiana State University. | Urban-Rural Planning Center, Ministry of Housing and UrbanRural Construction.

10.1021/es101987e

 2011 American Chemical Society

Published on Web 12/06/2010

River in 2005 and the Wuxi Water Crisis in 2007 were particularly serious events that were also discussed in one report of The World Bank (5). The process and origin analysis of these two accidents are reported in this paper from the viewpoint of the authors, who were the emergency water treatment directors and participants in the response to these accidents. To address such emergencies quickly and efficiently, the government of China has paid much attention to the emergency response under every foreseeable condition, including water supply shut-off and source water pollution. The central government requires its branches, the local government, and the water industry to establish contingency plans and teams for emergency response to environmental incidents. This study investigates the framework of water emergency response management and the main content of plans prepared at national and city levels. Technical difficulties are the critical obstacle in emergency drinking water treatment. Indeed, it is very difficult to develop emergency treatment technologies without sufficient preparation because many contaminants are originally not supposed to be present in the water source. It is also very difficult to implement these unusual technologies in a few days or enable the removal of contaminants present in high concentrations in the water. Accordingly, scientists and engineers in China are conducting research regarding these emergency treatment technologies. The recent progress and the principles of such technologies are included in this paper.

Process and Origin Analysis of Selected Accidents Nitrobenzene Spill in the Songhua River in 2005. This accident that occurred from November 13 to mid-December, 2005 was not the first environmental incident in China, but certainly one of the most important public hazard events in recent years. It was caused by an explosion in a petrochemical plant in Jilin Province. After the resultant fire was extinguished, about 100 tons of nitrobenzene, benzene, and aniline were released into the Songhua River through the sewage. Harbin, the capital of Heilongjiang Province, had to shut off its water supply for 4 days because the Songhua River is the sole water source for the city. During this period, the former Ministry of Construction (now the Ministry of House and Urban-Rural Construction, MHURC) sent a group of specialists to Harbin. The specialists proposed implementing a powdered activated carbon (PAC) adsorption process at the water intake to remove the nitrobenzene and other organic chemicals (6). This process played a critical role in the restoration of water supply on the evening of November 27, as the government had promised. Specifically, the nitrobenzene concentration was reduced from 0.061 mg/L in the water intake to 0.00081 mg/L, which is less than 5% of the standard (0.017 mg/L), after implementation of this emergency treatment process. This accident “has helped raise the awareness of government and the public on the importance of environmental emergency prevention and response, providing a unique opportunity for institutional changes” (5). The central government was shocked by the severe consequences of a pollution accident, which resulted in the need to shut off the water supply for four million people and an international issue between China and Russia. This incident also cost the government billions of RMB to restore the aquatic environment and site. Mr. Xie Zhenhua, the former Minister of SEPA, resigned due to this accident, which implies that greater attention should be paid to environmental protection. VOL. 45, NO. 1, 2011 / ENVIRONMENTAL SCIENCE & TECHNOLOGY

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total

2411 1842 1921 1843 1441 1406 842 462 474

year

2000 2001 2002 2003 2004 2005 2006 2007b 2008b

a This table was modified according to the China Statistics Yearbook 2007 and the China Statistics Yearbook 2008. The data source is the State Environmental Protection Administration (SEPA) before 2008 or the Ministry of Environmental Protection after 2008. b More details are included in the statistic reports prepared since 2007.

36.83 32.64 31.41 23.92 39.64 30.82 84.16 8.07 9.27 178.08 122.72 46.41 33.75 363.66 105.15 134.71 30.17 181.86 -------191 24 -------17 19 -------112 95 -------17 19 -------116 107 -------148 107 -------44 63 40 51 21 41 36 64 77 85 90 266 80 97 50 36 63 6 7 0 103 39 109 56 47 48 45 58 45 864 576 597 654 569 538 232 134 141

others natural disaster vehicle accident production accident illegal discharge air pollution

solid waste pollution

noise and vibration pollution

others (including ocean, ecology, nuclear) water pollution

1138 1096 1097 1042 753 693 482 178 198

reparations and fines (10 000 yuan) direct economic losses (million yuan) human illness due to accidents human fatalities due to accidents causes of the accidents 9

number of pollution and destruction accidents (time)

TABLE 1. Pollution and Destruction Accidents in Chinaa 162

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Wuxi Water Crisis in 2007. This crisis, which is also known as the odorous tap water accident, occurred in Wuxi City, Jiangsu Province from May 28 to early June of 2007. It was among the most important and complex public crisis affairs in China in recent years (7). During this incident, approximately two million residents in Wuxi received odorous tap water with a threshold odor number value in the thousands, indicating an extremely strong odor. The odor in the tap water originated from severely deteriorated source water-quality as a result of a sudden, massive die-off of a cyanobacteria mat in Taihu Lake (the water source). This die-off resulted in the release of a wide variety of volatile organic sulfur chemicals including methyl thiol, dimethyl sulfur, dimethyl disulfur, dimethyl trisulfur, and algal metabolite β-cyclocitral and was accompanied by industrial waste toluene. The strong and foul odor in the source water was also accompanied by the depleted level of dissolved oxygen, high chemical oxygen demand, and high ammonia nitrogen concentration. The specialist group sent by the former Ministry of Construction proposed the use of KMnO4 oxidation in the water intake and PAC adsorption in the influent to remove the odorous chemicals and other pollutants (8). This process successfully eliminated the odor from the tap water. There are different opinions regarding the origin of this crisis. The incident was initially attributed to a bloom of the cyanobacterium, Microcystis aeruginosa, in Taihu Lake (9). However, Yang et al. (10) subsequently argued that the intrusion of unknown black water agglomerate (Note: large area of Lake Taihu turned to be brown or black by the contamination of cyanobacteria massive die-off at that time) into the main water intake in Taihu Lake was the likely cause of the crisis, even though the visible bloom and black water were actually separate incidents. Based on the authors’ opinion (7), this crisis was the result of a combination of stresses associated with extreme eutrophication and the discharge of industrial and domestic wastewater that triggered the rapid decomposition of a cyanobacterial bloom and pushed the Taihu Lake ecosystem over a “tipping point” (11). This crisis was not caused by a single industrial facility or the annual algal bloom but rather the general mode of economic development around Taihu Lake. Wuxi and its surrounding area have experienced rapid economic development since the 1980s as a result of encouragement of a large number of privately owned enterprises. However, the importance of environmental protection was placed well behind that of increased GDP. Nevertheless, Wuxi and other cities in Yangtze Delta are now shifting their industries from chemical and painting industries to IT, alternative energy, and other green industries in response to this incident. Additionally, much more stringent environment protection policies have been implemented in these cities. Origin Analysis for the Frequent Occurrence of Accidents. The reasons for the frequency of emergency environmental affairs in China include the excessive pursuit of economic development at the cost of safe production, unreasonable selection of plant locations, very limited investment in environmental protection, and lenient environment protection policies and administrations. The basic information regarding 10 typical environmental accidents in China has been presented in the Supporting Information. The frequency of accident occurrence remained high in the past decade, according to the China Statistics Yearbooks, as a result of the increase of production and transportation of chemicals in China. Additionally, the excessive pursuit of economic development and rapid industrialization has made enterprises expand their production capability to unreasonable levels. For example, the Nitrobenzene Spill in the Songhua River was triggered during the trial production of

new line at Jilin Petrochemical Company (6), while a coal tar spill accident in Fanzhi County was caused by overloading a transportation vehicle (12). Both of these incidents were results of sacrificing safety in pursuit of profit and speed. The lack of price-setting rights for raw materials and staple products also compels Chinese enterprises to cut investment on safety and environmental protection to win successful international competition. As a result, many chemical plants do not have treatment facilities for waste disposal. Instead, they store the waste in tanks or ponds and release it intentionally, even though this process is illegal. Because such practices are illegal, many accidents have occurred on days during which there are floods and storms or at the end of the year. For example, the Yancheng Phenol Pollution Accident occurred when the managers were ordered to discharge the waste under the cover of flood in February 2009 (13). Also, the Beijiang Cadmium Pollution Accident (6) and Sandu Arsenic Pollution Accident occurred at the end of the year when the plants were conducting annual maintenance and discharging the waste (14). Poor selection of plant locations has exacerbated many environmental incidents. According to the former SEPA in 2006, as many as 81% of the total 7555 chemical and petrochemical construction projects were located in environmentally sensitive areas, such as rivers, lakes, and densely populated areas, while 45% of those were high-risk pollution sources (15). Due to the rapid upgrade of industry in the developed eastern areas of China, more and more chemical and petrochemical plants have moved to the central and western areas of China, which has put the fragile environment in these areas at risk. Unfortunately, environmental protection in these areas has not been strengthened at the same time. During the period the eighth, ninth, and 10th five-year-plans, the environmental protection investments have accounted for only 0.68%, 0.81% and 1.19% of GDP, not meeting the expected targets in the terms of ratios or growth rates (5, 16). The existing legislation and standards must be updated to suit the current situation. For example, the fine for water pollution accidents under the old version of Water Pollution Control Law is no more than 200,000 RMB (17), which is negligible when compared to the millions of RMB that the plants saved by not implementing environmental safeguards and even more negligible when compared to the total loss (see Table 1). The MOEP and the Environmental Protection Bureaus (EPB) in provinces, cities, and counties have not enjoyed equal status when compared to the economic departments. In many cases, the officers of the EPB have to approve some enterprises with a high risk of pollution under the pressure of local government. Overall, China will still be in a period of high risk of environmental pollution accidents for a fairly long time. To reduce the occurrence of water pollution accidents, China must change its development mode, strengthen its legislation and administration of environmental protection, and enhance its emergency response capacity.

Shift of China Environmental Protection Work after These Accidents Fortunately, after the Nitrobenzene Spill Accident and the Wuxi Water Crisis, the central government realized that the traditional development mode is unsustainable. As a result, the government has started to shift its focus from increasing the GDP to establishing a harmonious society with a resourcesaving and environmentally friendly mode of development, as emphasized in the 11th Five-Year Plan and the forthcoming 12th Five-Year Plan of China (18, 19). One clear signal for this shift is that the People’s Congress and the State Council elevated the State Environmental

Protection Agency to the Ministry of Environmental Protection in March 2008, which was endowed with more power to implement stricter policies. With the support of the central government and the public, MOEP strengthened environmental protection policies greatly in order to help to accelerate the shift of development mode, a feat requiring considerable external forces (20). MOEP has set up the goal of reducing chemical oxygen demand and sulfur dioxide emissions by as much as 10% during the period of the 11th Five-Year Plan and has pushed the local government and enterprises to upgrade the industry structure and to eliminate the severely polluted process and equipment. MOEP is also implementing stricter environmental impact assessment examinations for construction while holding the authority to ban all construction projects in a city if the reduction goal is not achieved. Legislation and financial policy are also used as the tools to strengthen environmental protection. The People’s Congress revised the Water Pollution Control Law in 2008 to update the penalty for a water pollution accident to as much as 30% of the direct cost of the accident. The polluted industries would also suffer more constraints when seeking loans and markets. Water supply safety has been regarded as the task of the highest priority in environmental protection (20). The State Council approved the “National Plan for Urban Water Source Safety (2006-2020)” in 2007, which MOEP, MHURC, MOH, MOWR, and other agencies are involved in. MOEP has laid much emphasis on the protection of water sources from pollution, including the ban on illegal pollution discharges within a protected area around water sources. MHURC is in charge of the updating of water treatment plants to tackle deteriorated source water and meet the new drinking water quality standard (GB5749-2006) (21). This standard was updated by MOH in 2006, and the number of the items covered by the new standard increased greatly from 35 in 1985 to 106 in its current form. There was resistance to updating the standard from the water treatment industry because their conventional drinking water treatment process could not treat polluted source water sufficiently to provide qualified drinking water. Water companies commonly complain that they receive unqualified raw water and cannot meet the increased requirements without sufficient financial support. According to the 2009 Environmental Quality Bulletin (22), the total water mass taken from 397 large urban water sources in the year 2009 was 21.76 billion tons, of which 27.0% was not qualified according to the environmental quality standards for surface water (GB3838-2002) (23). The central and local government should consider giving some funds to help water companies update their water treatment plants (WTPs). All these positive changes to environmental protection and related policies could be regarded as being triggered or accelerated by the Nitrobenzene Spill and the Wuxi Water Crisis. These two events should be regarded as the turning point in Chinese environmental protection, the influence of which could be compared with that of the public hazard affairs of the Minamata disease (24) and the itai-itai disease (25) in the 1970s in Japan.

Framework of Emergency Response Drinking water security is always considered a lifeline system, which means that it is essential to the public and should be maintained to meet the basic requirements regardless of cost. The strategy to guarantee drinking water security in China is to build a comprehensive framework with all stakeholders in the chain of water supply. Legislation and Plan. On August 30, 2007, the Committee of the National People’s Congress promulgated the Law of Emergency Response (26), which was put into effect on VOL. 45, NO. 1, 2011 / ENVIRONMENTAL SCIENCE & TECHNOLOGY

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FIGURE 1. Framework of water related affairs in China. November 1, 2007. Emergency drinking water treatment was included in the emergency response work according to the requirements of the legislation. This law includes the requirement of prevention and preparation, monitoring and alert, disposal and assistance, restoration and reconstruction, and liabilities. Specifically, the law requires the government to establish an emergency response system with the characteristics of uniform leadership, comprehensive harmonization, and administration according to different categories, with different responsibilities being taken at different levels and localization of management. This law also requires the State Council and provincial government to be in charge of the emergency response, management and the prepared plan. The State Council set up the Emergency Management Office (EMO) in April 2006 to direct the preparation work and command the emergency response at the national level. The local government also set up its own EMOs. The National Plan for Emergent Public Affairs (hereafter referred to as the National Plan) was promulgated by the State Council on January 8, 2006 (27). Water source contamination and the shut-off of water supplies are regarded as very severe and emergent affairs. These emergency events can be classified into four levels according to their nature, severity, size of the affected area, and possibility of control. A level 1 emergency in this plan is the most severe accident and is under the direct leadership of the State Council or its affiliated ministries and agencies. Level 2 events are under the administration of the provincial government and their affiliated departments. Level 3 and 4 events are under the administration of the municipal government and the county government. According to the National Plan, specialist groups must be involved in the emergency response process. Scientists, engineers and other professionals are invited to join this group and to provide technical support for the plan formulation, emergency treatment decision-making, staff training, and emergency response evaluation. In many cases, the specialist group has played a very important role in solving the problems, especially for complex and unusual events such as those in Harbin and Wuxi. 164

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Organization of Emergency Drinking Water Supply. For a specific emergency event, the framework of emergency drinking water treatment can also be divided into four levels: the national level, provincial level, city level, and county level. At the national level, the Ministry of House and Urban-Rural Construction (MHURC), Ministry of Environment Protection (MOEP), Ministry of Water Resources (MOWR), and Ministry of Health (MOH) are involved in the emergency response for drinking water. Their routine duties and emergency response responsibilities with respect to the water supply are ilustrated in Figure 1. The MHURC in the State Council, the Department of House and Urban-Rural Construction (DHURC) in provincial government, and the Construction Commission (CC) in local government are in charge of determining the national or local layout of water treatment facilities, guiding the operation of water treatment plants, and guiding the emergency drinking water supply. The section of urban construction in MHURC or DHURC or CC is in charge of affairs related to the water supply, including the emergency treatment. The MHURC has also prepared a plan for emergency drinking water supply, in which the level 1 event is defined by 50,000 families not having water for 24 h. The MOEP in the State Council, the Department of Environmental Protection (DOEP) in provincial government, and the Environment Protection Bureau (EPB) in local government are in charge of the water source quality monitoring, protection of the water source from pollution, and the remediation of polluted areas. The MOEP established the Emergency Response and Cause Investigation Center in 2009. This facility is in charge of the response, information delivery, and alerts associated with severe accidents. The MOEP’s prepared plan also concerns the water source (28). According to the plan, a level 1 emergency includes pollution that forces the city to shut off the water intake, while level 2 is defined as an emergency that requires an entire county to shut off its water intake. The organization of National Environmental Emergency Response is composed of the directive department, the commanding department, the supporting department, the consulting institutions and

FIGURE 2. Flowchart of general emergency response for drinking water treatment following source water pollution accidents or disasters in China. experts, the government at different levels, and the emergency treatment professionals. The MOWR, the Department of Water Resources (DOWR) and the Water Affairs Bureau (WAB) in local governments are in charge of water resources and water conservancy engineering, such as the management of rivers, lakes, reservoirs, channels, irrigation, and hydraulic power stations. The MOWR is also in charge of the drinking water supply in rural areas. In some cities, the responsibility of water supply management has been changed from the CC to the WAB in the name of government retrenchment and integration. The MOH, the Department of Health (DOH) in the provincial government, and the Branch of Health Inspection (BHI) in the city government are in charge of the quality of the finished water and the tap water in their precincts. These agencies often play the role of assessing whether or not the drinking water after emergency treatment satisfies the drinking water standard. The complex situation regarding water management is often criticized as having overlapping management, being characterized by buck-passing and lacking clearly defined duties and responsibilities; however, it is difficult to assign all of the related work to one ministry. From another point of view, this situation of multiple responsibilities also makes relevant ministries interdependent on each other. The coordination between different stakeholders is very critical to achieve successful emergency response. The city governments are the first to take the responsibility for drinking water security. These duties are conducted by different branches of the government and water companies. The local government requires the related agencies to set up the emergency response plan and clarify their responsibility in advance. When an emergency occurs, the government will call together the related agencies, coordinate their work, and assign their emergency response tasks. The CC, or WAB in some cities, is in charge of determining the layout of water facilities, including water treatment plants, backup water sources, emergency treatment facilities, etc. The EPB is in charge of water source protection, source water quality monitoring, disposal of polluted materials, and clean up of polluted areas. The BHI is in charge of quality assessment of finished water and tap water. In addition, the BHI is the only official branch that is permitted to announce whether or not the drinking water is safe for the public. Water companies are responsible for conducting emergency drinking water treatment after an accident and constructing emergency facilities prior to an accident. Process of Emergency Response for Drinking Water Supply. As mentioned before, the water supply should be maintained to meet the basic requirements, regardless of cost. Specifically, an emergency drinking water supply must be provided by treatment when unusual conditions such as

source water contamination, disasters, accidents, terrorist attacks, and other emergent affairs prevent the regular water supply from being maintained. This task places important responsibilities on the branch of water supply management and water companies. When emergency issues occur and water contamination is detected, comprehensive analysis must be conducted by the local monitoring station of the EPB or the water company. The report will be quickly delivered to the local government and other stakeholders. Then, the prepared plan of emergency response at different levels will be triggered according to the severity of the emergency. Each stakeholder is also required to take part in the process of emergency response. The flowchart of emergency response is shown in Figure 2. Monitoring will be conducted on an hourly basis until the source water quality returns to normal. Local EPBs have been establishing on-site monitoring facilities at important water sources. The parameters of real time monitoring may include the turbidity, pH, temperature, total organic carbon, ammonia nitrogen, phosphate, metals, algae surrogates (chlorophyll or phycocyanin), or other toxic materials. Some large cities also invest heavily in the construction of biosensor instruments at their water intakes. Once contamination occurs, it will be accompanied by the fluctuation of normal parameters, such as color, odor, pH, total organic carbon, and ammonia nitrogen, which will alert the real time monitors and personnel. Then, further identification of chemicals will be conducted by comprehensive analytical methods, such as gas chromatography and mass spectrography. An inspection of the polluter will be conducted by EPB immediately to find the specific components of contaminants. Moreover, the offender could be sentenced to jail and fined for illegal discharge according to Water Pollution Control Law and other related regulations. Once the information regarding water quality contamination is verified, professionals of the water company must make the right choice for emergency response as quickly as possible. Indeed, their suggestions are very important for the government to make the right decision. Generally, the water company will shut off the water intake under threat and switch to the backup water source if available. The MOWR and local WABs are required to support the water source switch. It is also useful to have more than one WTP to handle emergency situations. Under such conditions, the water company can close the affected WTPs and increase the output of other facilities. However, the efficiency depends on the redundancy of these WTPs and the possibility of drinking water delivery via a connecting water main in the distribution system. Therefore, the layout and control of the system are very important for maintaining water security in one city. The respective branches of water management and the water VOL. 45, NO. 1, 2011 / ENVIRONMENTAL SCIENCE & TECHNOLOGY

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company are responsible for preparing the layout of the system. Unfortunately, high flexibility requires sufficient redundancy and high cost. If the government does not provide subsidies, the local water company may be unwilling to provide such a high level of security. Under situations in which the only water source of the city is contaminated, the emergency treatment technology will be the last line of defense. This situation is not rare in China because it is difficult to find enough backup water sources to satisfy the huge population on condition of limited water resources. Under these conditions, some pretreatment reagents would be added into the pipe at the water intake. This process also needs to be adjusted according to the guidelines, which are discussed in the following sections. The tap water quality will be inspected closely by the BHI, which will monitor daily the contaminants and all of other items listed in the water quality standard. The emergency treatment cannot bring any other item over the criteria, even if it is just a sensory item and not toxic. It is a very tough work to satisfy all criteria in the emergency situation.

Emergency Drinking Water Treatment Technologies China has also invested heavily in developing emergency technologies to prevent water pollution accidents. The MHURC has been supporting research institutions and water companies to facilitate the development of emergency drinking water treatment technologies. The Ministry of Science and Technology (MOST) currently has a large project that supports the development of technologies to respond to different environmental pollution accidents. The MOEP also supports research that guides pollution control and site remediation. In 2008, the government of China declared that it would invest more than 100 billion RMB to support the National Major Projects of Science and Technology Development. Water pollution control and treatment was included as one of the 16 special projects, alongside projects including large aircraft development, manned spaceflight and moon exploration, and next-generation nuclear power. In this Water Special Project, the subproject of emergency drinking water treatment technologies has received a great deal of attention. Five types of emergency treatment technologies have been developed to form a fairly comprehensive system covering the pollutants (29, 30) that are listed in the standard of drinking water and source water. The principles for choosing the emergency treatment technologies include high efficiency in the removal of pollutants, ease of construction and operation, coordination with conventional processes, and reasonable costs. The PAC adsorption technology was developed to remove organic chemicals from water. Its capacities for 35 pollutants were determined through jar and pilot tests, while systems that could handle the pollution accidents were developed. Additionally, chemical sedimentation technology was designed to remove heavy metals from water. To accomplish this, the pH values required for 12 types of heavy metals to form the nonsoluble species were determined in the lab and verified in pilot tests. Moreover, chemical oxidation and reduction technology was developed to remove reductive or oxidative chemicals. Air stripping technology was also tested for the removal of volatile pollutants from water. This technology is capable of removing 11 types of short-chain chloro-hydrocarbons and achieving 80% of removal with an air/water ratio below 10. Enhanced disinfection technology was also developed to improve the efficiency in inactivation of pathogens. The parameters of each emergency treatment technology for the contaminants listed in the Drinking Water Quality Standard were obtained via jar tests and pilot tests by ten large water companies in China and not just from references. 166

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For example, there has been a great deal of research conducted to evaluate activated carbon adsorption (31-33). However, the equilibrium equations for some chemicals at high concentrations were different with those obtained at low concentrations near the criteria of drinking water standard. Moreover, the efficiency of these processes was influenced greatly by the concentration of other materials in the source water and PAC characteristic.

Implications and Suggestions The following conclusions and suggestions are made based on the findings presented here. (1) The drinking water supply in China will be threatened by environmental pollution accidents in the coming decades. As a result, China must change its development mode, strengthen its legislation and administration of environmental protection, and enhance its emergency response capacity. (2) The central and local governments are aware of the severe consequences of environmental pollution accidents. Therefore, they have established a framework to address different types of accidents and prepared response plans. This framework has played an important role in maintaining emergency water supply following accidents. (3) Water professionals in China have been developing comprehensive emergency treatment technologies for the water supply, which are able to cover the majority of pollutants in the drinking water quality standard. This comprehensive system includes PAC adsorption technology for organic chemicals, chemical sedimentation technology for heavy metals, chemical oxidation and reduction technology for reductive or oxidative chemicals, air stripping technology for volatile pollutants, and enhanced disinfection technology for pathogens.

Acknowledgments This project was supported by the “Water Pollution Control and Treatment Special Project” (Funding No. 2008ZX07420005). Researchers from Beijing Waterworks Group Co. Ltd., Shanghai Monitoring Station of water quality, Guangzhou Water Supply Co., Shenzhen Water Group Co. Ltd., Jinan Monitoring Station of water and wastewater quality, Wuxi Water Co., Harbin Water and Wastewater Co., Tianjin Water Works Group Co., Chengdu Water Works Co. Ltd., and Dongjiang Water Works Co. Ltd. also contributed greatly to validation of the emergency treatment technologies.

Supporting Information Available Tables S1-S3 and Figures S1. This material is available free of charge via the Internet at http://pubs.acs.org.

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