The zero-emission desalination rate of the reverse osmosis membrane group is low, analyze the reason

The zero-emission desalination rate of the reverse osmosis membrane group is low, analyze the reasons for the low

by:Ocpuritech     2021-05-20
Group reverse osmosis membrane desalination zero emission rate is low, analyze the reasons for the low author of the article: general equipment in use after a period of time, most of the equipment will appear abnormal operating conditions, the reverse osmosis membrane desalination rate that is set down pressure rise High, the water production increased slightly. After each chemical cleaning, the pressure difference of the reverse osmosis membrane group basically returned to normal, but the desalination rate of the zero-discharge technology showed a phenomenon of continuous decline month by month, resulting in a high conductivity of the membrane water production, affecting It is used by subsequent users. Analysis of the reasons for the low desalination rate of the zero-discharge technology: The factors that cause the high salt permeability and high water production of the reverse osmosis membrane are: physical factors (O-ring leakage, water back pressure, membrane surface wear, etc.), scaling or colloidal fouling And film oxidation. After on-site investigation, the conductivity of the water produced by each single membrane tube is close, and no O-ring leakage is found; in addition, the entire processing system is brand new, and the running time is not long, so there is no abnormal system operation caused by physical factors. ; If it is fouling or colloidal fouling, it can be completely recovered by chemical cleaning, but the desalination rate continues to decrease after each chemical cleaning, and the abnormal operation caused by fouling or colloidal fouling does not exist. The possible reason is that the reverse osmosis membrane is oxidized. The reverse osmosis membrane is oxidized, and it is very likely that the concentration of residual chlorine in the membrane water is too high. Because the chlorine resistance of the composite membrane is very poor, residual chlorine will cause irreversible oxidation of the composite membrane, so in the composite membrane RO system, the feed water is generally not allowed to contain residual chlorine (or its mass concentration is less than 0.1mg/L), so RO feed water After the system is chlorinated and sterilized, it is necessary to consider adding a reducing agent or filtering through activated carbon to eliminate residual chlorine. The reducing agent is generally NaHSO3. The reducing agent is generally added to the security filter. 1. Reducing agent reaction speed During normal operation, control the mass concentration of residual chlorine in the ultrafiltration product water to be 0.3~0.8mg/L. As long as sufficient reductant dosage is ensured, the reaction speed of reductant and residual chlorine is very fast. Will affect the removal effect of residual chlorine. 2. Dosing amount of reducing agent After theoretical calculation, 1.34mg of NaHSO3 reducing agent can remove 1.0mg of residual chlorine. In engineering practice, 3.0mg of NaHSO3 needs to be added for every 1.0mg of residual chlorine removed.
Custom message
Chat Online 编辑模式下无法使用
Chat Online inputting...
WhatsAPP图标