Improvement of biodegradability of PVA-containing wastewater by ionizing radiation pretreatment

Background

Polyvinyl alcohol (PVA) has been widely used as sizing agents in textile and manufacturing industry, and it is a refractory compound with low biodegradability.

Objective

The objective of this paper was to treat the PVA-containing wastewater using gamma irradiation as a pretreatment strategy to improve its biodegradability and to determine the roles of different kinds of radical species played during pretreatment.

Methods

Gamma radiation was carried out in a ⁶⁰Cobalt source station, PVA concentration was analyzed by using a visible spectrophotometer and specific oxygen uptake rate (SOUR, milligram of O₂ per gram of mixed liquor volatile suspended solids (MLVSS) per hour) was measured by a microrespirometer.

Results

The results showed that the biodegradability of PVA-containing wastewater with low initial concentration (e.g., 327.8?mg/l) could be improved greatly with increasing irradiation dose. However, PVA gel formation was observed at higher initial PVA concentration (e.g., 3,341.6?mg/l) and higher irradiation dose, which inhibited PVA degradation by aerobic microorganisms. However, the formed gel could be separated by microfiltration, which led to more than 90% total organic carbon (TOC) removal.

Conclusion

Ionizing radiation could be used as a pretreatment technology for PVA-containing wastewater, and its combination with biological process is feasible.