MBR Membrane for wastewater Chemical offline Cleaning Steps and Recovery cleans Process
Standard chemical cleaning is a key to managing chemical fouling & microbiological growth in the permeate pipes and to sustaining high membrane performance. Standard chemical cleaning should be started if the membrane is fouled (trans- membrane pressure has risen by 50 mbar from its initial operating level at the same permeated water flow rate), or if increased levels of Total Coliform or E.Coli bacteria are determined.
From a preventive maintenance point of view, more frequent standard chemical cleanings applied with lower chemical concentrations are more effective in sustaining high permeability and low bacteria counts in permeate than less frequent cleanings with higher chemical concentrations.
Typical Design of Standard Chemical Cleaning
The type of chemical cleaner and the frequency of cleaning will depend on the type of foulant and the rate of fouling. Organic and biological fouling is inherent in MBR plants since they are biological in nature. Inorganic fouling may also be present depending on the wastewater characteristics and chemicals added to the treatment process (e.g., metal salts addition for phosphorus removal). Standard conditions are described in the chapter 3.5.3 and from a preventive point of view, recommended standard chemical cleaning is at lower concentrations and higher frequency:
Perform standard chemical cleaning with 1,000-2,000 ppm NaOCl. Perform standard chemical cleaning with 2 g/l citric acid at pH
