Suitability and Cost of Nanofiltration Membrane Process in Drinking Water Treatment Plants in Taiwan
Dr. Jong-Nan Chen
|關鍵字:||極微濾薄膜、台灣自來水淨水廠、適用性、藍氏飽和指標、分流處理、成本;Nanofiltration, Drinking Water Treatment Plants in Taiwan, suitability, LSI, bypass treatment, cost|
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.