Optimized Design And Implication Of RO Desalination Of Groundwater

The watersources of reverse osmosis often includes surface water and groundwater. The compound of groundwater usually is steady. Basically groundwater has a little suspending particles and colloid. Its silt dense index is small, and its turbidity is low. The pretreatment of RO can be simplified, so groundwater often acts as the watersources of RO. However, when groundwater flowed along soil and rocks, it dissolved the dissoluble mineral, calcium and magnesium carbonates, so its hardness was high. Because of the RO membrane had concentrating effects, the concentration of Ca2+ and Mg2+ would increase 3 times, then on the membranes' surface dirt was deposited. The regular running process of the whole RO devices would be destroyed. The membranes lifespan would be shortened. Therefore adopting optimized design, selecting antiscale are the key problems of RO system's design.This paper introduced three main ways to control scaling. They were ion-exchange, adding acid and adding antiscale. Especially after contrasting the ion-exchange and adding antiscale in the aspects of their original investment, economic running process, the extent of complicated operation, environmental pollution, and their adaptability of the groundwater's RO desalination were advanced as soon as the concentrated water's LSI was lower than 2.5, And the latter way should firstly be selected because of its more simple equipments, more economic investment, less running fee and more simple operation.To test the dependability of adding antiscale technology, full experiments were done in 40 m3/h water pure equipments of Sichuan Jinlu Resin Ltd. Co. MDC 220 was added into the feed water, and a little amount of hydrochloric acid were added to adjust pH value. The results showed that when LSI was 2.3, adding 3ppm MDC220 and controlling pH at 7.2, the scaling couldn't appear.This paper also explained the design of RO desalination of 60 m3/h water pure equipments in details, and emphatically discussed the judging ways of scaling of indissoluble salts, the LSPs calculation and the antiscale principles. Based on these we optimized the design and selected Flocon 260 as antiscale. This method was more advanced and simple than ion-exchange and it could save 270 thousand yuan in equipments' investment.In December of 2002 the 60 m3/h water pure equipments were put into use. Hitherto the running process was always regular. Per ton water pure spent antiscale of 0.26 yuan, while adopting ion-exchange per ton water spent 0.79 yuan. So according to these our devices saved 274.8 thousand yuan per year, and if the membranes lifespan was 3 years, 824.4 thousand yuan would be saved in all. The economic profits were very considerable.