Abstract

Abstract Although the total reuse rate of municipal wastewater was 8.8% in China in 2012, water crisis is forcing China to increasingly develop water reuse. Urban reuse is comparatively poor and has significant potential to be promoted in China. It is a sensitive matter whether to include kitchen wastewater in grey-water reuse in water-deficient areas when kitchen wastewater accounts for a large proportion of total domestic water consumption. Concentrations of chemical oxygen demand, BOD5 (biochemical oxygen demand), and total organic carbon in kitchen wastewater are comparatively lower in China than in other countries, but a high concentration of nitrogen from washing tableware and rice makes it difficult to meet nitrogen requirements in Chinese guidelines. Whether kitchen wastewater should be included in grey-water reuse in China needs further study. Aerobic biological processes combined with physical filtration and/or disinfection is preferred in grey-water treatment, and how to balance the investment and treatment costs with reuse criteria still needs to be researched further. The promotion of reclaimed water for toilet flushing faces resistance in China. The necessity and effectiveness of existing restrictions in water reuse guidelines for toilet flushing in China are in doubt and need further discussion.

Highlights

  • Drought and water shortage are the key factors for water scarcity in arid and semi-arid areas in the world

  • It is sensible to include kitchen wastewater in the case where it accounts for a large proportion of domestic water consumption in water-deficient areas

  • Owing to a large amount of low polluted water from washing uncooked food, the concentrations of chemical oxygen demand (COD), BOD5, and total organic carbon (TOC) in kitchen wastewater are comparatively lower in China than in other countries

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Summary

INTRODUCTION

Drought and water shortage are the key factors for water scarcity in arid and semi-arid areas in the world. The purpose of this paper is: (1) to analyze the current state and potential of wastewater reuse in China and to propose possible solutions for improving water reuse rates; (2) to study the current situation regarding quantity and quality of grey-water in China and to analyze the feasibility of greywater reuse in China; (3) to summarize grey-water treatment technologies and propose advice on proper application; and (4) to compare the guidelines of water reuse in China and other countries, and propose suggestions for maintaining biological stability of reclaimed water in toilet flushing. Some of the compounds are considered potentially hazardous (e.g., ammonia nitrogen promotes the growth of nitrobacteria in pipelines and can reduce the inactivation rate of chlorine; dissolved solids may cause scaling (Zhao et al ) Whether these parameters are necessary for the assessment of reclaimed water for toilet flushing has not been studied. 6.0–9.0 Not unpleasant 5 1.0 after 30 min, 0.2 at point of use Chromaticity DS (mg/L) BOD5 (mg/L)

5.8–8.6 Not unpleasant 2 free
Findings
CONCLUSIONS
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