China's wastewater discharge standards in urbanization: evolution, challenges and implications.

Background and Purpose: China's environmental problems and pollution control have global implications. China's water pollution has been increasing with its urbanization and industrialization. Although great efforts have been taken to keep its wastewater discharge standards in pace with the water pollution development and technological advances, many challenges remain. A summary of the past achievements and lessons as well as the current problems in water pollution may provide a basis for future improvements in China and a reference for other countries.

Methods: Statistical data are summarized to reveal the evolution of China's population, wastewater discharge and corresponding discharge standards over the past four decades. In particular, the specific control indexes and number of controlled items are discussed in details. The present water pollution situation is clearly illustrated by the water pollution map and the water quality distribution diagram. A comparison between China's present wastewater discharge standards and those in the USA and the EU are also presented to find the possibilities for future improvement.

Results: The historical origins, major challenges and future perspectives of China's wastewater discharge standards are overviewed. The barriers and ongoing efforts for standards formulation and implementation are highlighted. Some suggestions for future endeavors are given.

Conclusions: China's wastewater discharge standard system has seen significant improvement over the past decades, but it still has many defects and limitations. Nonetheless, unprecedented great efforts are underway to address all these challenges. More stringent standards and subsequently a cleaner water environment in China can be expected in the near future.