PrintPrimary and secondary treatment processes
Figures 10.11 and 10.12 illustrate the primary (physical) and secondary (biological) treatment processes, respectively. The primary treatment of sour water contaminated with oils and solid particles involve the stripping of dissolved H2S using steam, float/sink density separation for skimming the floating oil, and the settling tanks to separate heavier oil and solids, usually in multiple stages, before the treated water can be directed to public treatment facilities. The secondary treatment uses micro-organisms to further remove organic contaminants.
Simplified primary treatment diagram. Sour water and steam undergo stripping. H2S is removed and sent to a Claus Unit. Everything else is sent, with wastewater to the separator (float, sink). Oil floats and is removed, the rest goes to two successive settling tanks (which sometimes include flocculation agents) where oils and solids are removed. Finally, the remaining water is sent to a public treatment facility.
Simplified secondary treatment diagram. National pollutant discharge elimination (NPDS) permits are needed according to the clean water act of 1972 and amendments of 1977. The materials collected are considered toxic and are regulated by the resource conservation and recovery act of 1976.
Wastewater and air enter biological contactors. From there some products go to surface disposal and some of the products go to biomass waste, then dewatering and is finally turned into biocoke.