BACKGROUND: One of the most important industrial sources of volatile organic compounds (VOCs) is related to coating and painting applications. In this sense, photocatalytic oxidation can become an innovative and promising alternative for the remediation of air polluted by VOCs. In this study the UV photodegradation of m-xylene, toluene and n-butyl acetate, as representative compounds of paint solvents, was carried out in an annular reactor using a TiO 2 -glass wool supported catalyst.

BACKGROUND An expanded granular sludge bed (EGSB) reactor is commonly used in anaerobic treatment of industrial wastewater. To develop applications to remove solvents, the granular sludge retention within the reactor must be improved. RESULTS This work evaluated the addition of chitosan as a strategy to enhance granulation in an EGSB reactor used to treat a wastewater containing 1‐methoxy‐2‐propanol and ethanol. Two reactors, one with chitosan supplementation and the other without chitosan (control), were operated in parallel. Greater particle size was obtained in the reactor with chitosan. The retention of solids within the reactor was clearly improved. Moreover, the settling properties were clearly enhanced in the first stages (days 0–44) in terms of settling velocity and sludge volume index. The time required to obtain 80% removal of 1‐methoxy‐2‐propanol was shortened from 38 days to 22 days when chitosan was supplemented. CONCLUSIONS The addition of chitosan is a promising alternative to enhance granulation in EGSB reactors that are used to treat glycol ethers. A single addition rapidly improves the settling properties of the granular sludge; this method could be used as an operational strategy when partial degranulation occurs. This work provides useful guidelines on the enhancement of biomass retention while operating an EGSB. © 2017 Society of Chemical Industry