饮用水原水水质与制水工艺级联组合的经济可持续性评价

Economic sustainability evaluation of cascaded combinations of raw water quality and water treatment processes for drinking water

摘要

【目的】在我国脱贫攻坚取得全面胜利、饮水安全得到总体解决的背景下,部分水资源短缺和环境脆弱地区,特别是苦咸水分布区,其安全供水的经济可持续性仍面临挑战。已有的以苦咸水为饮用水源的研究结果,制水成本差异大,不确定性高,主要原因是未从原水水质、制水工艺与饮用水标准三者间关系角度联合研究,成果只反映其中某一过程。【方法】从饮用水制水的完整链路出发,构建“原水水质-制水工艺-饮用水标准”全过程级联组合链路关系及其经济性评价模型。该模型以原水溶解性总固体(Total Dissolved Solids,TDS)为关键特征指标,系统分析不同TDS浓度的原水在不同制水工艺下满足不同饮用水标准时的制水成本,进而与我国主要省会城市及计划单列市现行第一阶梯水价比较,评估其不同级联组合制水的经济可持续性。【结果】在我国现行饮用水标准下,当原水TDS≤1 000 mg/L时,常规处理或超滤工艺即可稳定达标,制水成本低、经济可持续性强;当TDS为1 000~1 500 mg/L时,需配置纳滤工艺,制水成本有所升高,但仍在可持续范围内;当TDS继续升高至1 500~2 000 mg/L时,需采用反渗透工艺方可达标,此时制水成本显著增加,经济性接近临界可持续状态;当TDS>2 210 mg/L时,制水成本将超过现行最高水价(4.16元/m³),经济可持续性堪忧。将上述方法应用于我国西北地区某地级市,结果表明,在现有水源条件下,依靠常规工艺仅能使21.46%的人口稳定获得达标水;引入纳滤工艺后,可将此比例提高至58.92%,其余41.08%人口则必须采用成本更高的反渗透工艺来保障饮用水的水质安全。【结论】从原水到制成水的级联全过程是饮用水生产不可分割的链条,所构建的级联组合经济可持续性评价方法可为不同原水水质条件下的制水工艺优化配置和供水水源选择提供科学依据,并可为城乡供水规划和饮用水标准持续提升背景下的供水安全保障提供参考。

Abstract

[Objective] Against the background of China's comprehensive victory in poverty alleviation and the overall improvement of drinking water safety, the economic sustainability of safe drinking water supply in some water-scarce and environmentally fragile areas, especially brackish-water areas, remains challenging. Existing studies using brackish water as a drinking water source report large differences in water production costs and high uncertainty, mainly because the relationship among raw-water quality, water treatment processes, and drinking water standards has not been studied jointly, and the reported result reflect only one part of the whole process. [Methods] Starting from the complete chain of drinking water production, the whole-process cascaded combination relationship of " raw water quality-water treatment process-drinking water standard" and its economic evaluation model were constructed. Using raw-water total dissolved solids( TDS) as the key indicator, the model systematically analyzed the water production costs of raw water with different TDS concentrations under different treatment processes for meeting different drinking water standards, and then compared them with the current first-tier water prices in major provincial capitals and municipality with independent planning status in China to evaluate the economic sustainability of different cascaded combinations. [Results] Under China's current drinking water standards, when raw-water TDS was ≤1 000 mg/L, conventional treatment or ultrafiltration could stably meet the standard, with low water production cost and strong economic sustainability. When TDS was 1 000 ~ 1 500 mg/L, nanofiltration was required, and the cost increased but remained within a sustainable range. When TDS further rose to 1 500~2 000 mg/L, reverse osmosis was required to meet the standard, at which point the water production cost increased significantly and economic sustainability approached a critical threshold. When TDS exceeded 2 210 mg/L, the water production cost exceeded the current highest water price of 4. 16 CNY/m³, and economic sustainability became a concern. Application of the method to a prefecture-level city in northwestern China showed that, under existing source-water conditions, conventional processes alone could provide compliant water to only 21. 46% of the population. After introducing nanofiltration, this proportion increased to 58. 92%, while the remaining 41. 08% must rely on the higher-cost reverse osmosis process to ensure drinking water safety. [Conclusion] The complete cascade from raw water to finished water is an inseparable chain in drinking water production. The proposed economic evaluation method for cascaded combinations can provide a scientific method for configuring different treatment processes and selecting water supply sources for drinking water based on raw-water quality, and can serve as a reference for guiding urban and rural water supply planning and ensuring supply safety against the background of continuously rising drinking water standards.

关键词

原水水质 / 饮用水标准 / 溶解性总固体 / 制水工艺 / 经济可持续性 / 影响因素 / 供水安全 / 环境脆弱地区

Key words

raw water quality / drinking water standards / total dissolved solids / water treatment processes / economic sustainability / influencing factors / water supply safety / environmentally fragile areas

基金资助

国家自然科学基金项目(52300246)

国家自然科学基金项目(U2243601)

水圈科学与水利水电工程全国重点实验室(SKL-IOW-2024TC2401)