The ability of peroxidases and laccases enzymes to treat organic pollutants is reviewed. Enzymatic methods generally have low energy requirements, are easy to control, can operate over a wide range of conditions and have a minimal environmental impact. Peroxidases and laccases have broad substrate specificities and can catalyze the oxidation of a wide range of toxic organic compounds. The results show that an enzymatic oxidation can diminish the toxicity of some polycyclic aromatic hydrocarbons (PAHs), phenols, organophosphorus pesticides and azo dyes in laboratory and some field conditions. Due to the hydrophobicity and low aqueous solubility of these substrates, reactions are usually performed in the presence of organic solvents. However, it was detected that organic solvents can provoke enzyme denaturation, unfavorable substrate partition, inhibition or stabilization of enzyme–substrate complexes, depending on the enzyme, substrate and organic solvent used. Strategies to overcome these problems are proposed. Additionally, the low stability of heme-containing peroxidases to hydrogen peroxide, the low reaction rates of laccases, the mediators toxicity, the limited availability and high costs of these enzymes are other limitations detected for commercial applications. Due to field reaction conditions are more complex than laboratory conditions efforts have to be made to achieve the cheap overproduction of these biocatalysts in heterologous hosts and also their modification by chemical means or protein engineering to obtain more robust and active enzymes.

Potential use of oxidative enzymes for the detoxification of organic pollutants

The implementation of increasingly stringent standards for the dis- charge of wastes into the environment has necessitated the need for the develop- ment of alternative waste treatment processes. A review of research directed toward developing enzymatic treatment systems for solid, liquid and hazardous wastes is presented. A large number of enzymes from a variety of di†erent plants and microorganisms have been reported to play an important role in an array of waste treatment applications. Enzymes can act on speci-c recalcitrant pollutants to remove them by precipitation or transformation to other products. They also can change the characteristics of a given waste to render it more amenable to treatment or aid in converting waste material to value-added products. Before the full potential of enzymes may be realized, it is recommended that a number of issues be addressed in future research endeavors including the identi-cation and characterization of reaction by-products, the disposal of reaction products and reduction of the cost of enzymatic treatment.

Potential Applications of Enzymes in Waste Treatment

Potential applications of peroxidases

Composition, morphology, and surface characteristics of solid substrates play critical roles in regulating immobilized enzyme activity. Grapheme oxide (GO), a novel nanostructured material, has been illustrated as an ideal enzyme immobilization substrate due to its unique chemical and structural properties. Physical properties and catalytic activity of GO immobilized horseradish peroxidase (HRP) and its application in phenolic compound removal are described in the present study. HRP loading on GO was found to be much higher than that on reported substrates. The GO immobilized HRP showed improved thermal stability and a wide active pH range, attractive for practical applications. The removal of phenolic compounds from aqueous solution using the GO immobilized HRP was explored with seven phenolic compounds as model substrates. The GO immobilized HRP exhibited overall a high removal efficiency to several phenolic compounds in comparison to soluble HRP, especially for 2,4-dimetheoxyphenol and 2-chlorphenol, t...

Horseradish Peroxidase Immobilized on Graphene Oxide: Physical Properties and Applications in Phenolic Compound Removal

Phenol is a major pollutant in the wastewater because of its presence in the effluent of major processing and refining plants. It has severe effect on human being, both short term and long term. Various methods are used for removal of the phenol from wastewater such as adsorption, photodecomposition, volatilization and other various biological and non-biological methods. In the present study attempt is done to present the survey of the research on the phenol removal by various methods. The methods such as Polymerization, electrocoagulation, extraction, photodecomposition, advanced oxidation and ion exchange were used effectively by various investigators. These methods are reported to be efficient for the phenol removal. Suitable method for phenol removal can be selected based on availability of the material, extent of separation required and properties of phenolic effluent.

http://www.ijsrp.org/research-paper-0413/ijsrp-p16116.pdf

K.W. Saadi

Papers

Phenol polymerization and precipitation by horseradish peroxidase enzyme and an additive