Method for separating and recycling food processing wastewater rich in tannin and sodium chloride through nanofiltration membranes

Abstract

The invention discloses a method for separating and recycling food processing wastewater rich in tannin and sodium chloride through nanofiltration membranes. The method comprises the following steps of pretreatment and microfiltration, nanofiltration, evaporation and crystallization, and tannin extraction. Compared with the existing waste water processing technology in the prior arts, the method for separating and recycling food processing wastewater rich in tannin and sodium chloride through nanofiltration membranes has the advantages that: the method is an integrated technology comprising the processes of nanofiltration separation, evaporation and crystallization, and tannin extraction; especially, processes of removing tannin from rinsing wastewater through nanofiltration separation and recycling the salt-containing rinsing wastewater are combined with processes of dissolving and extracting tannin through ethanol, thus a water consumption, a salt consumption and a COD pollution load are reduced greatly in the whole production process; in the whole process of purifying and recycling wastewater through nanofiltration membranes, a recycling rate of wastewater is over 70%, in the process of tannin extraction, a total recovery rate of sodium chloride is over 75% and an extraction rate of tannin is over 70%; and more importantly, tannin difficult to be treated are recovered and high value-added tannin product can be produced out so that an economic benefit and a social benefit of production are improved.

Description

technical field [0001] The invention relates to wastewater recycling technology, in particular to a method for separating and recycling food processing wastewater rich in tannin and sodium chloride by nanofiltration membranes. Background technique [0002] Fruits such as olives, plums and red bayberries are rich in carbohydrates, proteins, vitamins or calcium, phosphorus, iron and other nutrients, and are an excellent food production raw material. In some areas of our country, an industrial chain of planting, processing and sales has been formed, which is of great significance to the local land afforestation, regional characteristic economic development and the construction of new and efficient agriculture. [0003] Taking olive fruit as an example, in addition to being eaten fresh, it is also processed into various pickled or soaked olive fruit products. The main process of its processing is: material selection → pre-treatment → pickling → rinsing → hammer cracking → cookin...

AI Technical Summary

Problems solved by technology

The above methods all separate tannins from the water body, which need to consume a large amount of coagulants and adsorbents, but it is difficult to recover and utilize tannins and phenols, and cannot eliminate the salt substances in such wastewater

At the same time, due to the large volume and water quality characteristics of this type of wastewater, if simple evaporation crystallization and reverse osmosis separation and purification are used, not only the investment in fixed assets is huge, but also the operation cost is expensive, so it cannot be put into production at present.

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