What method other then ordinary chem cleaning for RO bio and sand effected membranes? what is the temper limit for membranes chemical cleaning ?

The basic cleaning method used for RO is Clean in place (CIP) using High PH and Low PH cleaning. For high PH, the desired temperature is around 35 deg C for optimized reaction. For Low PH cleaning, temperature does not play a big factor for optimizing the reaction, thus 25 to 35 deg C is okay.

chemical cleaning by acid and alkaline (HCL - NAOH)

TEMPER " 35

There is no other method for membrane cleaning rather then chemical cleaning, the temprature limit for membrane chemical cleaning from 25 to 40

I think most commonly used pre-filters are sediment filters (multi-media filters) used to remove sand, silt, dirt, particulate and other sediment material. Charcoal filters are used to remove oxidizing compounds, such as chlorine, to protect the membranes, particularly thin film composite (TFC) and thin film material (TFM) membranes. Carbon pre-filters are not routinely use when the system uses cellulose tri-acetate (CTA) membranes, but most companies use the TFC/TFM filters.

Most of reverse osmosis manufacturer recommends chemically enhanced cleaning Elements should be conducted when one or more of the below mentioned parameters are applicable:

• The normalized permeate flow drops%

• The normalized salt passage increases5 -%

• The normalized pressure drop (feed pressure minus concentrate pressure)  increases -%

The most effective cleaning method in the case of biofoulingis an oxidizing agent such as chlorine, hydrogen peroxide and peracetic acid.Cellulose acetate membranes tolerate oxidizing agents, but the more popularthin-film polyamide reverse osmosis membranes do not. Of nonoxydizing cleanersfor biofouling situations formaldehyde, glutaraldehyde and quaternary ammoniumcompounds may be used for polyamide membranes. If the fouling is caused byintracellular byproducts from microorganisms, various enzymatic cleaning agentshave proved to be effective.

 In the case of mineral fouling, chemical cleaning agents are used. Acid generally will remove inorganic salts. Cellulose acetate membranes do not tolerate low or high pH values, whereas polyamide embranes generally can be cleaned down to pH2. Acetic acid, which also is a complexing agent for some metals, often is used with good results. Complexing agents like quaternary ammonium compound operate better at elevated pH values, which renders them of little use for cellulose acetate membranes.

using DBNPA (Bioside) as slug dosing will help in removing the biofilm and organics, specially when the feed water is biological active.