An SEM-REM-Based Study on the Driving and Restraining Mechanisms and Potential of Reclaimed Water Utilization in China

In order to promote the efficient use of reclaimed water in China and make water resources allocation better structured, this paper analyzed the factors that drive and restrain the current utilization of reclaimed water and unveiled their correlation and hierarchy in a way to develop a non-recursive structural framework of what drives and restrain reclaimed water use. By structural equation modeling (SEM), the transmission path of affecting factors was identified, the contribution of the factors quantified, and key indicators for potential prediction selected. On that basis, a random-effects model (REM) was built to predict the potential availability of the country’s reclaimed water. Meanwhile, parametric confidence intervals at 10–90% quantile levels were described, given the uncertainty of REM parameters. The results showed that four indicators for potential prediction, namely the total amount of wastewater treated, the density of water pipelines in built-up areas, investment in facilities for reclaimed water treatment, and the processing of applications for water treatment patents, are intertwined with the utilization of reclaimed water. Overall, the REM for potential prediction produced more precise fitting results, with the most significant fitting error standing at 5.9%. Going ahead, China is set to maintain the rapid growth in reclaimed water use, and up to 13.7 billion cubic meters of reclaimed water is expected to be available by 2025. This will help better structure the urban water supply and render regional water recycling more efficient.