Biodesalination and treatment of raw hypersaline produced water samples using indigenous wastewater algal consortia

Indigenous microalgae consortia present in domestic wastewater, were acclimatized to three real produced water (PW) samples collected from different oil fields. PW, a byproduct of oil mining and extraction, is hypersaline and toxic. Therefore, progressive adaptation mechanism was applied for acclimatization in a steadily decreasing dilutions of PW. After acclimatization, algae consortia were used for biodesalination and treatment of PW. The acclimatization lag phase was longer when the dilutions were reduced. The predominant species present in the consortia were Chlorella. One PW sample (onshore with largest initial salinity) showed the earliest adaptation (13 days) at lowest dilution. Chloride and salinity removal efficiencies of 25% and 22% were achieved, respectively, along with significant decrease in total dissolved solids (TDS) and conductivity in the different samples. The same PW sample showed highest removal of chloride (25%, from initial 53 g/L to final 40 g/L) and COD (44%). Another PW sample showed highest removal of salinity (22%), electrical conductivity (9%), TDS (20%) and total organic carbon (26%), as well as highest increase in alkalinity (86%). Removal efficiencies were minimum in the last PW sample which also showed less adaptability to the same dilution ratio of other two PW samples.