Reduction of organic load in wastewater of wheat starch and gluten industry using membrane separation technology

Annually cca. 30.000 m(3) of wastewater is produced during the processing of wheat flour to produce wheat starch and vital wheal gluten. Wastewater is generated in the process of concentration of starchy milk, where it is separated as a lighter phase. After separation this wastewater is the precipitated and decanted. In decanted water, which is characterized as wastewater from wheat starch industry, among other substances, few organic and inorganic compounds are left behind. Wastewater contains about 12000 mg/1 sry matter, the chemical oxygen demand is about 30.000 mgO(2)/1, and suspended solid is about 8.000 mg/1. Next to starch particles. Wastewater contains soluble proteins, pentosans, cellulose and gluten. Wastewaters solid effluents contain in average starch of 70%, protein 18%, ash 7% and cellulose 5%. The removal of organic load, primarily starch, is one of the major problems in the wheat starch industry and can be carried out using membrane separation technology. This type of technique enables concentration and separation without the use of heat. The particles are separated based on their molecular weight and shape, using specially designed ceramic membranes, where the driven force is pressure. For experiments, wastewater is at first deposited for 2, 3 and 4 hours, after which it decanted. Content dry the substances in the decanted decanted samples after 2, 3 and 4 hours amount to 8, 100-9,500 mg/1, 7,600-8,000 mg/1 and. 7,000=7,500 mg/1, respectively. Decanted samples of wastewater, after different deposition time, represent feeding mixtures for microfiltration. Microfiltration is carried on using ceramic membranes (GEA, Germany) with two different pore size: 200 nm and 2, 5 and at transmembrane pressure in the range of 1-3 bars. During microfiltration, the permeate flux is observed, as well as some physicochemical parameters of the treated wastewater. It is observed that using 200 nm membrane, transmembrane pressure at 1 bar the permeate flux is 15 time less than the flux of distilled water. This reduction in flux means that resistion is created during the microfiltration of wastewater, i.e. to create an additional filtration layer on the surface particle membranes and compounds present in wastewater. In the samples of permeate, dry matter, chemical consumption of oxygen and suspended matter is determined, and in the retentate the content of the dry matter were measured. By using a membrane technology, the dry matter of waste water is reduced by 68%, chemical consumption of oxygen decreases by 90% and the suspended matter in wastewater is also recorded, and this significantly decreases by 94%.

کلیدواژه ها:

Microfiltation ، Ceramic membrane ، Wheat starch industry Wastewater