| At present, the membrane technology has been widely used in water recycling field. Based on separation performance of membrane, MF and UF were used for pretreatment commonly, RO and NF were used for deep treatment. The combination of membrane technology in water recycling can realize the "three highs" needs (high efficiency, high recovery rate and high quality effluent), with have a high degree of automation equipment, a good quality and stable for outlet water, the process of high efficiency and space-saving. MF was mainly used for intercepting suspend and matenals in water. RO was mainly used for intercepting variety of inorganic ions, colloidal substance and large molecules solute. MF as pre-processing method of RO system can ensure system operating stably, extra washing period and RO film life time. In the research, MF-RO was used for the advanced treatment of tannery wastewater secondary effluent and analyzed it from the following aspects.The experimental study of MF. MF treated simulation tannery wastewater. The results shows that with higher precision of the filtration, the quality of water was better. The water rate decreased while precision of the filtration rising. According to the experiment request, this paper choose5μm MF membrane; with the increase of the temperature, the water yield was improved, while the quality of outlet water get poor; the increase of filtering time can influence water yield, but the production water quality can get better; operating pressure and pH can affect water rate, and have little effect on water quality.For RO system, among this factors, the temperature, pH, operating pressure and wastewater concentration are considered. The influencing degree of this factor was: Temperature> Wastewater concentration> pH> Pressure. By the results, the optimum conditions were set:temperature was20℃, pH=7, operating pressure was0.6MPa, wastewater concentration was initial concentration.The experimental study of practical tannery wastewater, When the optimum conditions were set:temperature was20℃, pH=7, operating pressure was0.6MPa, wastewater concentration was initial concentration, the removal rate of COD was higher than92%; the removal rate of Cr was higher than97%; the removal rate of NH3-N is lower, but normal this rate is reach more76%; the removal rate of total hardness was higher than85%, each index was more excellent than the requirement of tannery wastewater reuse.The proportion of two kinds of cleaning agents were decided by cleaning experiment,1.5%HC1+1.0%NaOH and2%citric acid+0.5%NaOH. In the tests, alkali wash for40min and acid wash for40min, then rinse clean for10min. |
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