極微濾薄膜處理程序在台灣自來水淨水廠之適用性與成本分析之研究

Abstract

近年來，由於社會大眾對於飲用水水質的要求逐漸提升與相關法規標準的日趨嚴格，台灣現有水處理廠之更新、升級已到刻不容緩的地步，因此本研究擬應用極微濾薄膜在台灣自來水淨水工程上，針對國內各中、小型水廠之水質資料進行調查與研究，建立極微濾薄膜實廠化適用水質之基本資料，提出台灣省各水廠使用極微濾薄膜水處理系統的建議。同時配合商業上可使用之軟體進行基本設計與初設成本評估，並累積實驗室與模型廠薄膜長期操作之數據，進行操作及維護成本之分析。 分析台灣省自來水公司各區處淨水廠之水質飽和特性，北區淨水廠之原水水質具有腐蝕的傾向，適合當作薄膜程序之低化學積垢潛能進流水，南區與東區淨水廠之原水則易造成薄膜表面碳酸鈣沈積發生，需增加化學性前處理進行調理才能適用。考量薄膜處理程序之前處理成本，北區與少數特殊之南區水廠濁度較高，故其物理性前處理成本較高，而南區與東區之水廠藍氏飽合指數較高，故其化學性前處理成本較高。NF薄膜程序通常需考量合適之前處理、藥洗程序與廢液處理。針對新竹第一淨水廠水質與設備，建議採用混合比為4的分流處理方式混合後出水，而薄膜系統回收率85 %，產水5000噸、12500噸、25000噸水廠之極微濾薄膜處理程序成本，分別為5.11元/m3’、3.99元/m3’、3.78元/m3，每單位水量之處理水價已相當合理，且符合第三階段飲用水標準。發現當混合比大於4時，加上現行水價成本，其總處理水價約可維持在15元/m3左右。從增建薄膜處理程序之成本觀點來看，北區與東區水廠因水質較佳，故增建極微濾薄膜處理程序之成本較低;而南區與部分中區之水廠因水質較差，故其增建極微濾薄膜處理程序成本就相對較高。

As the levels of drinking water regulation is getting more and more stringent, the update of drinking water treatment plants in Taiwan is becoming necessary. This study focus on NF membrane treatment process applied in drinking water treatment plants in Taiwan. We investigate raw drinking water quality in small or middle-sized drinking water treatment plants in Taiwan and bring up some suggestion that about suitable membrane treatment raw water quality information. Furthermore, we apply previous investigation and use membrane treatment plant design software to estimate that NF membrane treatment plant’s capital cost and Q&M cost. Analysing LSI variation for drinking water treatment plants in Taiwan showed that these raw water in drinking water treatment plants in the northern Taiwan region have corrodible tendency and are suitable for NF membrane treatment raw water, but those raw water in drinking water treatment plants in the Southern Taiwan region are easy to deposit CaCO3 and must to step up additional chemical-pretreatment equipment. because these raw water in drinking water treatment plants in the North Taiwan region and those raw water in several special plants in the South Taiwan region that have high turbidity; they need higher physical-pretreatment cost. these raw water in drinking water treatment plants in South Taiwan region and those raw water in several special plants in East Taiwan region that have high LSI value, so they need higher chemical-pretreatment cost. A full-scale NF membrane treatment plant usually contains suitable pretreatment segment, chemical cleaning membrane element segment, and concentrate disposal segment. According to water quality in HSINCHU area, we suggest that suitable mix ratio＝4(filtrate and permeate), recovery＝85%(permeate), and the reasonable cost per m3 product water for 5000 m3,12500 m3 and 2500 m3 NF membrane plant is 5.11, 3.99 and 3.78 dollars/m3 respectively. When the mix ratio is more than 4, the total unit water treatment cost (NF treatment cost and conventional treatment cost) are approximately 15 dollars/m3. Conventional treatment process combined with NF membrane treatment process is a suitable and low cost advanced treatment process for drinking water treatment. According to cost-benefit for NF membrane, the result showed that building NF membrane plant in the northern Taiwan region or eastern Taiwan region is higher cost-benefit, but building NF membrane plant in the southern Taiwan region or midst Taiwan region is lower cost-benefit.