| The use of river water has a long history,low price,simple,convenient and practical facilities.In the case of substantial improvement of surface water quality,the direct use of river water has significant benefits of saving water and reducing carbon.There are dense river networks in Shanghai,and the water surface rate of rivers and lakes reaches 10.11%.In recent years,the environmental quality of surface water has been greatly improved.In 70 major river sections of Shanghai,the proportion of classⅡ～Ⅳ reaches 99%,which provides conditions for various industries to directly take river water.This paper compares and analyzes the differences between the direct use of river water and tap water in treatment mode,water delivery distance,energy input and water price.The results show that the direct use of river water has obvious advantages of saving water and reducing loss,reducing water cost,saving energy and reducing carbon.According to the statistical data,the river water intake and management in Shanghai can be divided into four categories: public water supply,thermal power industry,agriculture and dispersed industry,accounting for 41.6%,34.0%,21.0% and3.4% of the water intake in 2020,respectively.Compared with the widely accepted use of river water by public water supply,thermal power industry and agriculture,only 304 water users in dispersed industries directly use river water in the whole city.The paper conducted a field survey on 70 water users in 14 industries,including non-metallic mineral products,and the results showed that:(1)The direct use of river water for products accounts for 58%,mainly for concrete production and paper making,17% for cleaning,15% for clothing rinsing,15% for greening,10% for golf course greening,and 10% for cooling of various processes;(2)Water users are evenly distributed in 9administrative regions of Shanghai,and it is convenient for each region to use river water;(3)The behavior of direct river water intake conforms to the water intake specification,and has the characteristics of coordinated utilization with rain water and less sewage discharge;(4)It is very convenient for users to feedback river water,but there are some problems,such as high investment cost for water resources demonstration in the early stage,many supervision procedures for water intake and high sewage treatment cost,which restrict the promotion of river water.Combined with the demand of water quality and quantity for river water of customers,this paper calculates the water demand of each part by using water quota method,and quantifies the potential of Direct access to river water in Shanghai in the short term.The results show that:(1)River water has potential utilization in four types of uses: industrial water for concrete production,clothing rinsing,paper making,cooling and cleaning;Green water in golf courses,parks,residential areas and other greening;Sanitation management water for road and public toilet flushing;Car washing industry water;(2)Similar to the current situation of direct river water intake,industrial water is still mainly used,requiring 283.3204 million m3 of water,accounting for74.7%;(3)The water used for greening is only concentrated in golf courses and a few high-grade residential areas,but in the future,the river water used in parks and affiliated green Spaces can reach 29.6303 million m3;(4)The water demand for environmental sanitation management and car washing is large,but there is no river water at present,and the water demand can reach 68.1123 million m3,accounting for 17.5%.The total amount above is 380.0366 million m3,and the direct use of river water in 2020 is only249 million m3,a difference of 131.0636 million m3 from the ideal water demand.In addition to continuing to promote the direct use of river water in industry,Shanghai should also focus on tapping the potential of river water utilization in environmental sanitation management,car washing and afforestation.Give full play to the advantages of direct access to river water.The paper explores the water-saving and carbon reduction benefits of direct river water compared with tap water,which can save 0.311m3/m3 of water loss of public water supply water production and water transportation,and save 4.59 yuan /m3 of water cost,and reduce the power consumption of water treatment,transportation and other links of 0.162 kwh/m3,and reduce carbon dioxide emissions of 0.128kg/m3.If the city gives full play to the utilization potential of river water,the direct utilization of river water can reach 380.636 million m3,saving 118.1998 million m3 of water,generating economic benefits of 1.745 billion yuan for users and reducing 48,600 tons of carbon dioxide emissions.The paper analyzes the restrictive factors of river water intake,including poor water quality,high cost of applying for "water intake permit",weak water price guidance and cumbersome water intake management process.The countermeasures and suggestions are put forward as follows: to maintain surface water environmental governance and prevent water quality repetition;Promote the pilot demonstration of regional water resources,reduce the demonstration process of water resources for single user;Reduce or exempt sewage treatment fees for "zero" discharge water users;Gradually realize the concentration of " water supply by differently quality " to industrial enterprises.This paper was supported by the "Water Resources Management Supervision and Inspection" project in 2021 of Shanghai Water Supply Management Center. |
