Water Quality Changes during Rapid Urbanization in the Shenzhen River Catchment: An Integrated View of Socio-Economic and Infrastructure Development
2. Material and Methods
2.1. Study Area
2.2. Water Quality Data
2.3. Methods to Estimate the Pollutant Load
3.1. Temporal Trend of Water Quality
3.2. Water Quality vs. Pollutant Load Discharges
3.3. Pollutant Load Generation vs. Removal
3.4. Capacity for Pollutant Load Removal
4.1. Water Pollution Characteristics during Urbanization
4.2. Effects of Socio-Economic Measures
4.2.1. Socio-Economic Measures
- “Centralized control of waste” was first instituted in China in 1999, requiring all levels of government to generate economies of scale and improve efficiency in waste disposal [14,26]. Based on this principle, ecological industrial parks are encouraged, in which businesses cooperate with each other and the local community in an attempt to reduce waste and pollution and efficiently share resources (such as information, materials, water, energy, infrastructure, and natural resources).
- To accelerate the transformation of economic development and promote industrial restructuring and upgrading, the local government has compiled the “catalog of industrial structure adjustment” annually since 1993 , in which the industries are categorized into three groups: encouraged, restricted, and prohibited. The prohibited industries include printing and dyeing, tinning, plating, and eight other labor-intensive industries. According to these catalogs, the industries with high labor productivity and low pollution emission were encouraged to develop, e.g., the cultural industry, the electronic information industry, the biotechnology and pharmaceutical industry, and the advanced material and new energy industry.
|Socio-economic measure||Deadline requirements for pollution control||1998||A total of 173 companies that had severely polluted water bodies were required to reduce pollution by the deadline, and 43 were ordered to close down.|
|Centralized control of waste||1999||Focusing on petroleum discharge control, 336 companies were examined.|
|2004||Focusing on both V-ArOH and petroleum discharge control.|
|2000||An electroplating park was established, and all wastewater from the electroplating industry can now be effectively collected and treated in the park before discharge.|
|Catalog of industrial structure adjustment||1993–2009||The industries were categorized into three groups: encouraged, restricted, and prohibited. Industries with high labor productivity and low pollution emission were encouraged to develop.|
|WWTP construction & technology improvement||Binhe WWTP||1985–1995||Wastewater treatment capacity: 2.5 × 104 m3/day in 1985, 3.0 × 105 m3/day in 1995; actual wastewater treatment: 1.1 × 105 m3/day in 1995.|
|Luofang WWTP||1998–2002||Wastewater treatment capacity: 1.0 × 105 m3/day in 1998, 3.5×105 m3/day in 2002; actual wastewater treatment: 2.2 × 105 m3/day in 2002.|
|Caopu WWTP||2003||Wastewater treatment capacity: 1.5 × 105 m3/day; actual wastewater treatment: 5.0 × 104 m3/day.|
|Wastewater transfer and marine discharge system||Stage I, II & III||1990–2001||Wastewater transfer capacity: 5.0 × 104 m3/day in 1990, 7.4 × 105 m3/day in 2001; actual wastewater transfer 2.4 × 105 m3/day in 2001.|
|Sewer system improvement||For Binhe WWTP collection area||1999||Wastewater collection capacity: 1.5 × 105 m3/day.|
|Wastewater transfer and marine discharge system collection area||2003||Wastewater collection capacity: 2.8 × 105 m3/day.|
|For Luofang WWTP collection area||2004||Wastewater collection capacity: 2.6 × 105 m3/day.|
|For Caopu WWTP collection area||2006||Wastewater collection capacity: 1.5 × 105 m3/day.|
4.2.2. Effects of “Deadline Requirements” and “Centralized Control”
4.2.3. Effects of Industrial Structure Adjustment
4.3. Effects of Wastewater Infrastructure Development
4.3.1. Wastewater Infrastructure
- Before 1994, Binhe WWTP was the only WWTP in the catchment (Figure 1). This WWTP was equipped with secondary treatment; its BOD5, NH3-N and TP removal rates were 80%, 48% and 81%, respectively; its volumetric treatment capacity was less than 5.0 × 104 m3/day. Two WWTPs, Luofang WWTP with secondary treatment and Caopu WWTP with advanced primary treatment (Figure 1), were constructed and then upgraded between 1996 and 2003. In 2005, the total volumetric treatment capacity in the northern catchment rapidly increased to 1.5 × 106 m3/day, while the BOD5, NH3-N and TP removal rates increased to 92%, 57% and 81%, respectively.
- A wastewater transfer and marine discharge system was constructed in 1990 and 5.0 × 104 m3/day of wastewater was transferred outside of the Shenzhen River catchment and discharged into the sea through a long-distance discharge pipe. The system was gradually enlarged between 1997 and 2001, and its transfer capacity increased to 7.4 × 105 m3/day by 2001.
- A large amount of wastewater in the catchment could not be collected and conveyed to the WWTPs due to non-existent or low-efficiency sewer systems during urbanization. Several projects had been carried out to retrofit or improve the sewer systems in the catchment over 1999–2006, and the amount of wastewater actually collected by the sewer system increased from 4.4 × 105 m3/day in 1999 to 9.4 × 105 m3/day in 2006.
4.3.2. Limitations of Wastewater Infrastructure
- The construction of wastewater facilities lagged behind population and economic growth in the early stages of urbanization (before 1995). In the study area, socio-economic planning and wastewater facilities planning are performed by the Shenzhen Development and Reform Commission (SZDRC) and Shenzhen Municipal Water Affairs Bureau (SZWAB), respectively. The socio-economic planners of SZDRC are not expected to fully apprehend the capacity limitations of existing/future wastewater facilities in their decision-making process and usually assume that facilities construction can match the pace of socio-economic growth, while wastewater facilities planners of SZWAB do not fully account for the extent of rapid socio-economic development in decision making. Facilities planners usually estimate certain socio-economic growth potentials in their planning, however the facilities planners may over- or under-estimate the growth and fail to make timely adjustment in facilities development. Therefore, wastewater generation and treatment capacity may be mismatched during rapid urbanization . These mismatches caused water quality deterioration in the early stage of urbanization.
- The sewer network construction lagged behind the construction of WWTPs in the catchment. The wastewater treatment capacity of WWTPs increased much faster than the amount of wastewater actually collected by the sewer system in the catchment (Figure 6a). One reason is that the local government focused on improving wastewater treatment capacity by constructing WWTPs. However, constructing a sewer network is more difficult and requires more time to construct, and due to the delay in construction the wastewater collection capacity increased slower than the treatment capacity.
- The existing sewer networks were operated at a low efficiency level. Most of the early developed areas in the catchment are densely populated, and overcrowded multi-story buildings are usually prevalent in these areas. While the buildings provide cheap accommodation for the massive number of workers immigrating from other Chinese cities or villages, they usually have poorly installed pipelines which result in the mixing of sewage flows with rainfall runoff. In addition, to fully utilize the indoor living space, local residents alter balconies in the buildings to re-equip them for toilet, kitchen or laundry use, leading to sewage discharge into the river via rainwater pipes. Due to the poor environmental management and environmentally harmful behavior, wastewater cannot be efficiently collected into the existing sewer systems.
- The WWTPs have relatively low removal efficiencies for nutrient pollutants. The existing WWTPs in the Shenzhen River are equipped with secondary or advanced primary treatment technology. The WWTPs have high removal rates for organic matter, such as BOD5, but are not as effective in removing nutrient substances, such as nitrogen and phosphorus, and unfortunately these nutrient substances are predominant pollutants in densely populated catchments such as the Shenzhen River catchment. For example, the NH3-N pollutant removal rate of the WWTPs in the catchment was only 55% in 2009. Therefore, although BOD5 has significantly decreased, NH3-N has remained at a high level since 1995.
4.4. Solutions on Water Quality Changes
4.4.1. Wastewater Infrastructure Construction
4.4.2. Socio-Economic Policies Regulation
4.4.3. Increasing Environmental Awareness
4.4.4. Integrated Measures on the Water Environment
Conflicts of Interest
- Lehmann, S. Can rapid urbanization ever lead to low carbon cities? The case of Shanghai in comparison to Potsdamer Platz Berlin. Sustain. Cities Soc. 2012, 3, 1–12. [Google Scholar]
- Rana, M.M.P. Urbanization and sustainability: Challenges and stragety for sustainable development. Environ. Dev. Sustain. 2011, 13, 237–256. [Google Scholar]
- Zhao, S.; Da, L.; Tang, Z.; Fang, H.; Song, K.; Fang, J. Ecological consequences of rapid urban expansion: Shanghai, China. Front. Ecol. Environ. 2006, 4, 341–346. [Google Scholar]
- Ren, W.W.; Zhong, Y.; Meligrana, J.; Anderson, B.; Watt, W.E.; Chen, J.K.; Leung, H.L. Urbanization, landuse, and water quality in Shanghai 1947–1996. Environ. Int. 2003, 29, 649–659. [Google Scholar]
- Chang, H. Spatial and temporal variations of water quality in the Han River and its tributaries, Seoul, Korea, 1993–2002. Water Air Soil Pollut. 2005, 161, 267–284. [Google Scholar]
- Kannel, P.R.; Lee, S.; Kanel, S.R.; Khan, S.P.; Lee, Y.S. Spatial-temporal variation and comparative assessment of water qualities of urban river system: A case study of the River Bagmati (Nepal). Environ. Monitor. Assess. 2007, 129, 433–459. [Google Scholar]
- Boeder, M.; Chang, H. Multi-scale analysis of oxygen demand trends in an urbanizing Oregon watershed, USA. J. Environ. Manag. 2008, 87, 567–581. [Google Scholar]
- Ferrier, R.C.; Edwards, A.C.; Hirst, D.; Littlewood, I.G.; Watts, C.D.; Morris, R. Water quality of Scottish rivers: Spatial and temporal trends. Sci. Total Environ. 2001, 265, 327–342. [Google Scholar]
- He, H.M.; Zhou, J.; Wu, Y.J.; Zhang, W.C.; Xie, X.P. Modelling the response of surface water quality to the urbanization. J. Environ. Manag. 2008, 86, 731–749. [Google Scholar]
- Groppo, J.D.; de Moraes, J.M.; Beduschi, C.E.; Genovez, A.M.; Martinelli, L.A. Trend analysis of water quality in some rivers with different degrees of development within the São Paulo State, Brazil. River Res. Appl. 2008, 24, 1056–1067. [Google Scholar]
- Ma, J.Z.; Ding, Z.Y.; Wei, G.X.; Zhao, H.; Huang, T.M. Sources of water pollution and evolution of water quality in the Wuwei basin of Shiyang river, Northwest China. J. Environ. Manag. 2009, 90, 1168–1177. [Google Scholar]
- Duh, J.D.; Shandas, V.; Chang, H.; George, L.A. Rates of urbanisation and the resiliency of air and water quality. Sci. Total Environ. 2008, 400, 238–256. [Google Scholar]
- Qin, H.P.; Su, Q.; Khu, S.T. An integrated model for water management in a rapidly urbanizing catchment. Environ. Model. Softw. 2011, 26, 1502–1514. [Google Scholar]
- Zhang, K.M.; Wen, Z.G. Review and challenges of policies of environmental protection and sustainable development in China. J. Environ. Manag. 2008, 88, 1249–1261. [Google Scholar]
- Shao, W. Effectiveness of water protection policy in China: A case study of Jiaxing. Sci. Total Environ. 2010, 408, 690–701. [Google Scholar]
- Su, S.L.; Li, D.; Zhang, Q.; Xiao, R.; Huang, F.; Wu, J.P. Temporal trend and source apportionment of water pollution in different functional zones of Qiantang River, China. Water Res. 2011, 45, 1781–1795. [Google Scholar]
- Weng, Q. A historical perspective of river basin management in the Pearl River Delta of China. J. Environ. Manag. 2007, 85, 1048–1062. [Google Scholar]
- Miljašević, D.; Milanović, A.; Brankov, J.; Radovanović, M. Water quality assessment of the Borska Reka river using the WPI (water pollution index) method. Arch. Biol. Sci. 2011, 63, 819–824. [Google Scholar]
- Nikolaidis, C.; Mandalos, P.; Vantarakis, A. Impact of intensive agricultural practices on drinking water quality in the EVROS Region (NE GREECE) by GIS analysis. Environ. Monitor. Assess. 2008, 143, 43–50. [Google Scholar]
- Su, Q.; Qin, H.P. Environmental and ecological impacts of water supplement schemes in a heavily polluted estuary. Sci. Total Environ. 2014, 472, 704–711. [Google Scholar]
- Liu, N.; Lu, R.F. Water Environmental Management in Shenzhen River and Deep Bay, 1st ed.; China Water Power Press: Beijing, China, 2006. (in Chinese) [Google Scholar]
- Census and Statistical Bureau of Shenzhen (CSBSZ). Statistical Year Book of Shenzhen 1985–2009; China Statistical Press: Beijing, China, 2010. (in Chinese) [Google Scholar]
- Environmental Protection Bureau of Shenzhen (EPBSZ). Water Quality Report of Shenzhen 1985–2009; EPBSZ: Shenzhen, China, 2010. (in Chinese) [Google Scholar]
- Environmental Protection Department of Hong Kong (EPDHK). River Water Quality in Hong Kong 1985–2009. Available online: http://www.gov.hk/en/residents/environment/water/riverwater.htm (accessed on 18 October 2014).
- Environmental Protection Department of Hong Kong (EPDHK). Guideline for Estimating Sewage for Infrastructure Planning; EPDHK: Hong Kong, China, 2005. [Google Scholar]
- MacBean, A. China’s Environment: Problems and Policies. World Econ. 2007, 30, 292–307. [Google Scholar]
- Zhang, K.M.; Wen, Z.G.; Peng, L.Y. Environmental policies in China: Evolvement, feature and evaluation. China Popul. Resour. Environ. 2007, 17, 1–7. [Google Scholar]
- Development and Reform Commission of Shenzhen (DRCSZ). Catalogue of industrial structure adjustment 1993–2009. Available online: http://www.szpb.gov.cn/fgzl/cydxml (accessed on 18 October 2014).
- Qin, H.P.; Su, Q.; Khu, S.T. Assessment of environmental improvement measures using a novel integrated model: A case study of the Shenzhen River catchment, China. J. Environ. Manag. 2013, 114, 486–495. [Google Scholar]
- Organica Food Chain Reactor. Lower infrastructure cost: Treating wastewater at the source eliminates the need for expensive infrastructure. Available online: http://www.organicawater.com/solutions/advantages/lower-infrastructure-costs (accessed on 29 September 2014).
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Qin, H.-p.; Su, Q.; Khu, S.-T.; Tang, N. Water Quality Changes during Rapid Urbanization in the Shenzhen River Catchment: An Integrated View of Socio-Economic and Infrastructure Development. Sustainability 2014, 6, 7433-7451. https://doi.org/10.3390/su6107433
Qin H-p, Su Q, Khu S-T, Tang N. Water Quality Changes during Rapid Urbanization in the Shenzhen River Catchment: An Integrated View of Socio-Economic and Infrastructure Development. Sustainability. 2014; 6(10):7433-7451. https://doi.org/10.3390/su6107433Chicago/Turabian Style
Qin, Hua-peng, Qiong Su, Soon-Thiam Khu, and Nv Tang. 2014. "Water Quality Changes during Rapid Urbanization in the Shenzhen River Catchment: An Integrated View of Socio-Economic and Infrastructure Development" Sustainability 6, no. 10: 7433-7451. https://doi.org/10.3390/su6107433