Industrial process wastewater
Liquid effluents typically include process and cooling water,
storm water, and other specific discharges (e.g., hydrotesting,
washing and cleaning mainly during facility start up and
turnaround). Process wastewater includes
Effluents from Lower Olefins Production
Effluents from steam crackers and relevant recommended
prevention and control measures are the following:
· Steam flow purges (typically 10 percent of the total dilution
steam flow used to prevent contaminant build-up) should
be neutralized by pH adjustment and treated via an
oil/water separator and air-flotation before discharge to the
facility’s wastewater treatment system;
· Spent caustic solution, if not reused for its sodium sulfide
content or for cresol recovery, should be treated using a
combination of the following steps:
o Solvent washing or liquid-liquid extraction for polymers
and polymer precursors;
o Liquid-liquid settler and/or coalescer for removing and
recycling the free liquid gasoline phase to the process;
o Stripping with steam or methane for hydrocarbon
removal;
o Neutralization with a strong acid (which results in a
H2S / CO2 gas stream that is combusted in a sour gas
flare or incinerator);