Nanofiltration-forward osmosis combined system adopting commercial nanofiltration membrane and forward osmosis membrane and application of nanofiltration-forward osmosis combined system

Abstract

The invention relates to a nanofiltration-forward osmosis combined system adopting a commercial nanofiltration membrane and a forward osmosis membrane and application of the nanofiltration-forward osmosis combined system. A nanofiltration system adopts cross flow filtration, water passes from the two sides of the membrane, the filtration pressure and the circular flow are regulated through a frequency converter of a gear pump, and a PLC (Programmable Logic Controller) controls the whole. The quantity of reflux of concentrated water is controlled through the regulation of a valve so as to achieve different recovery rates. The effluent of nanofiltration fresh water is measured by a mass flowmeter controlled by the PLC, the result is stored in a PLC storage unit, so that the flux of infiltration water is recorded and acquired. The nanofiltration water inlet temperature is controlled by a water bath and keeps consistent with the temperature of a forward osmosis system, and the concentratedwater of the nanofiltration system flows out to a raw material solution tank of the forward osmosis system. A raw material solution is placed on a balance connected to a computer, and the change of the mass within the time interval set in advance is transmitted into the computer. The temperatures of the raw materials solution and a driving liquid are controlled through the water bath and keep consistent with the temperature of the nanofiltration system. The design flow of the system is 60 L / h, and the removal rate of dissolved organic matters is more than 90%. The membrane is replaced at regular intervals. The system is cleaned at regular intervals.

Description

technical field [0001] The invention relates to a combined nanofiltration-forward osmosis system using a commercial nanofiltration membrane and a forward osmosis membrane and its application. It belongs to the technical field of membrane separation for water treatment, is suitable for medium and small water supply treatment systems, and can be designed and assembled in modules according to needs. Background technique [0002] At present, due to the deterioration of drinking water source water quality and the increasingly stringent drinking water quality standards, pressure membrane technology (reverse osmosis, nanofiltration, ultrafiltration and microfiltration) has shown great advantages in removing organic pollution in drinking water And application prospects, membrane technology is therefore also known as "the water treatment technology of the 21st century". While the pressure membrane efficiently removes organic pollutants, the soluble organic matter (Dissolved Organic ...

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Problems solved by technology

While the pressure membrane efficiently removes organic pollutants, the soluble organic matter (Dissolved Organic Matter, DOM) in the raw water tends to accumulate and attach on the membrane surface and inside the membrane pores, eventually leading to irreversible membrane fouling

The reduction of water production and water quality and the increase of additional energy consumption caused by membrane fouling often hinder the wide application of pressure membrane technology.

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