The application of a low purity soybean peroxidase (LP-SBP), obtained from wasted seed hulls, as catalyst for phenol polymerisation in aqueous solution in the presence of hydrogen peroxide is described. The polymers formed precipitate out from solution and may be readily separated by physico-chemical techniques. LP-SBP offers the advantage of reduced cost compared with horseradish peroxidase (HRP). The SBP activity in fresh hulls was greater than in aged hulls and was preserved at À10°C. There was a linear correlation between initial phenol concentration (1, 2, 5 and 10 mmol dm À3) and the minimum dosage of LP-SBP required to precipitate 95% of the phenolic polymers. Polyethylene glycol (molecular weight, 6000) at 1000 mg dm À3 did not extend LP-SBP lifetime. At all phenol concentrations tested, a retention time of about 100 min was suf®cient to achieve yields of 95%.

This work presents a process for phenol removal comprising a reaction step in which phenol is polymerized in the presence of an enzyme followed by a separation step involving dissolved air flotation (DAF). A crude preparation from horseradish roots was used as a low purity source of the enzyme horseradish peroxidase (HRP). The technical feasibility of the process was studied at bench scale using 1 to 10 mM synthetic phenol solutions. Experimental results showed the potential of the proposed technique. A phenol conversion higher than 99 % was observed at the polymerization step and an efficiency higher than 94 % was achieved at the separation stage. Despite the use of a low purity source of HRP, which increases the input of organic matter, the chemical oxygen demand (COD) decreased by 50 %

The estimate rice productivity in Brazil for the 2008/2009 season, is 12,149.35 thousand tons of grains, being Rio Grande do Sul (RS) state responsible for 61.34% of national production. The rice shell is usually burned for energy production, generating rice shell ash (CCA) as solid residue. CCA represents an average of 4% of the grain mass. In this way, RS state presents an estimated generation of 298.1 thousand tons of CCA in this period. Attempts to reuse this waste are constantly facing difficulties due to inherent CCA properties. This work aims to perform sorption bench tests to verify the possibility of using CCA to treat the effluent of the parboiled process. Tests efficiencies were expressed in terms of organic matter and turbidity removal. The use of a solid residue of the end of the process to treat the effluent of the very process is a strategy to minimize costs for waste management and contribute to the environment in a sustainable way. The sorption efficiency of CCA as an alternative sorbent material reached 78% of organic matter removal and 99% of turbidity removal.