Controlling pH in biological depuration of industrial wastewater to enable micropollutant removal using a further advanced oxidation process

Abstract

BACKGROUND: The accumulation of bicarbonates during the biological treatment of high organic strength wastewater has a negative impact on the remaining micropollutant removal through chemical oxidation due to its scavenging effect on hydroxyl radicals. In this study, a lab-scale sequencing batch reactor (SBR) was operated at circumneutral pH to avoid inorganic carbon accumulation, followed by Fenton and photo-Fenton processes to treat an agro-food industrial effluent with acetamiprid as a model pollutant at 100 g L −1 . A cost analysis of the operation strategy was performed. RESULTS:The pH control did not affect SBR efficiency (98% organic carbon biodegradation) but gave rise to different inorganic carbon concentrations in the effluents: 75.32, 10.81 and 5.7 mg L −1 at pH 8.0, 7.0 and 6.5, respectively. Both Fenton and photo-Fenton resulted in complete acetamiprid removal at pH 6.5 and 7.0 with high iron dosage (up to 80 mg L −1 ) but only photo-Fenton achieved this at acidic pH with 20 mg Fe L −1 . CONCLUSION: To remove micropollutant from biotreated wastewater by Fenton processes it is highly recommended to control pH at circumneutral values during the biotreatment. The reactant cost analysis showed a reduction of ∼80% to remove the micropollutant, even with photo-Fenton being carried out at pH 2.8.

A corporate water footprint case study: The production of Gazpacho, a chilled vegetable soup

“…They were detected in the wastewater as a result of the cleaning step applied to the fruits and vegetables processed. Amongst them, ACTM, a neonicotinoid insecticide, despite not being the most abundant (only 0.5 μg L −1 vs 3.3 μg L −1 of TBZ), is one of the most persistent (owing to its low reactivity in further chemical treatments) [13].…”

Wastewater Treatment by Advanced Oxidation Process and Their Worldwide Research Trends

“…This situation requires the development of alternative remediation technologies to limit the discharge of these compounds in the environment. Numerous scientific studies were recently reported proving the effective removal of micropollutants contained in actual urban wastewater [38,39]. Membrane bioreactors technology (MBR) combining conventional activated sludge (CAS) treatment with a membrane filtration system was reported as an alternative to increase the effluent quality decreasing the membrane cost [40,41].…”

Editorial

“…The collection included in the present issue is not exhaustive, but reflects the most relevant aspects on the state of the art, and the excellent potential of new materials with photocatalytic properties (Fe 2 O 3 /Al 2 O 3 , TiO 2 ‐SiO 2, iron on montmorillonite composites, N‐doped TiO 2 /PS aerogels, iron loaded hydrogels), as well as electrochemical processes for wastewater treatment. The applications regarding the combination of AOPs with biotreatment, water disinfection and abatement of emerging and persistent aqueous contaminants show the diverse contributions of very efficient teams of biologists, engineers and chemists working together.…”