Nanofiltration-Forward Osmosis Combined System Using Commercial Nanofiltration Membrane and Forward Osmosis Membrane and Its Application

Abstract

The invention relates to a nanofiltration-forward osmosis combination system adopting a commercial nanofiltration membrane and a forward osmosis membrane, and an application thereof. A nanofiltration system adopts crossflow filtration of water flowing through two sides of the nanofiltration membrane, the filtering pressure difference and the circulation flow rate are adjusted through the frequency converter of a gear pump, and a PLC is used to carry out total control. Valve adjustment is carried out to control the reflux quantity of concentrated water in order to obtain different recovery rates. Nanofiltration freshwater outlet water is determined by a mass flow meter controlled by the PLC, and the obtained determination result is stored in a PLC memory cell in order to record and obtain the flux of osmosis water. The temperature of nanofiltration inlet water is controlled by a water bath tank, and is same to the temperature of a forward osmosis system, and concentrated water of the nanofiltration system flows out to the raw material liquid tank of the forward osmosis system. A raw material liquid is placed on a balance connected to a computer, and the change of the weight of the raw material liquid in a preset time interval is transmitted to the computer. The temperatures of the raw material liquid and a driving liquid are controlled by the water bath tank, and are same to the temperature of the nanofiltration system. The flow rate designed by the system is 60 L / h, and the removal rate of dissolved organic matters is greater than 90%. The membranes can be regularly replaced, and the system can be regularly cleaned.

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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