Profitable wastewater treatment by directly recovering organics for volatile fatty acids production

A strategy of directly recovering organics for the production of volatile fatty acids (VFAs) was introduced to make wastewater treatment profitable. A sludge adsorption section was proposed to add before the conventional wastewater process for adsorbing the organics in wastewater by the excess activated sludge which was produced during biological wastewater treatment and returned from the secondary settling tank. Then, the excess activated sludge combining wastewater organics, called organics-enriched sludge, was anaerobically fermented for the production of high value-added VFAs. Results indicated about 70 % of wastewater organics could be source-recovered within 30 min. Most of the organics in wastewater could avoid being lost via carbon dioxide or synthesized into bacterial organisms, therefore, the total amount and overall bioavailability of the organics recovered from wastewater were greatly improved. Pilot-scale tests indicated VFAs production from wastewater organics was enhanced by 62.2 %. Mass balance analysis indicated 46.8 % of wastewater organics could be finally transferred into VFAs, only 12 % in conventional processes. Economic evaluations indicated source-recovering wastewater organics for VFAs production was a promising alternative to make wastewater treatment plants (WWTPs) profitable. Finally, an idealized organics transformation route for wastewater treatment was proposed based on this concept to make wastewater treatment profitable.