| Treatment process and description | advantages | Typical Risks and Problems |
|---|---|---|
| Gravity separation | Remove free O&G Simple design handle larger capacity Minimum mechanical and electrical equipment requirements Low operation and maintenance cost | Large are requirements due to relatively low flow or large tank Limited to removal of free O&G (no removal of oil droplets < 0.02mm or soluble oil) |
| Air flotation, dissolved air flotation, induced air flotation or mechanical air flotation | Remove both free and emulsified oil. Reduces TSS and COD Remove both floating and settable solids Very small and light particles can be removed completely in short time | High chemical consumption Relatively high sludge formation |
| Chemical flocculation with gravity separation or air flotation | Removal of high levels of suspended solids | Chemical sludge produced |
| Filtration sand, anthracite, multimedia, crushed graphite, oleophilically coated ceramic, hollow fiber membrane cartridge (ultra filtration) | Removal of suspended solids, separation of free, dispersed and emulsified oils | Backwashing, which requires subsequent treatment |
| Coalescence fibrous membrane | Removes total O&G Small and compact Easy operation and maintanance Low cost | Limited capacity Partial removal of emulsified oil Extensive pre treatment required high potential for fouling not practical for full scale operation |
| Membrane process reverse osmosis, ultra filtration, hyper filtration | Removal of soluble oil | Membrane fouling and limited life extensive pre treatment low flux rate not practical for full scale operation |
| Biologicla processes activated sludge | Effective soluble oil removal TSS and BOD reduction | Extensive pretreatment required to reduce the influent oil levels to 40mg/l |
| Carbon adsorption | Effective removal of all oil components | Expensive Extensive pre treatment required carbon must be regenerated or replace not practical for full scale operation |
