Advanced Oxidation Processes (AOPs) for Refinery Wastewater Treatment Contains High Phenol Concentration

Petroleum Refinery wastewater is characterized by a high phenol content. Phenol is toxic and resistant to biological processes for treatment of the petroleum refinery wastewater. The combination of an AOP and a biological process can be used for treatment of the refinery wastewater. It is necessary to conduct a study to determine the appropriate condition of AOP to meet the phenol removal level. Two AOP configurations were investigated: H2O2 / UV and H2O2 / UV / O3. From each process samples, COD, phenol and pH were measured. The oxidation was carried out until the targeted phenol concentration of treated effluent were obtained. The better result obtained by using process H2O2 / UV / O3 with the H2O2 concentration 1000 ppm. After 120 minutes, the final target has been achieved in which phenol concentration of 37.5 mg/L or phenol degradation of 93.75%.

Characterization of catechol 2,3-dioxygenase from Planococcus sp. strain S5 induced by high phenol concentration.

This study aimed at characterization of a new catechol 2,3-dioxygenase isolated from a Gram-positive bacterium able to utilize phenol as the sole carbon and energy source. Planococcus sp. strain S5 grown on 1 or 2 mM phenol showed activity of both a catechol 1,2- and catechol 2,3-dioxygenase while at a higher concentrations of phenol only catechol 2,3-dioxygenase activity was observed. The enzyme was optimally active at 60°C and pH 8.0. Kinetic studies showed that the K(m) and V(max) of the enzyme were 42.70 µM and 329.96 mU, respectively. The catechol 2,3-dioxygenase showed the following relative meta-cleavage activities for various catechols tested: catechol (100%), 3-methylcatechol (13.67%), 4-methylcatechol (106.33%) and 4-chlorocatechol (203.80%). The high reactivity of this enzyme towards 4-chlorocatechol is different from that observed for other catechol 2,3-dioxygenases. Nucleotide sequencing and homology search revealed that the gene encoding the S5 catechol 2,3-dioxygenase shared the greatest homology with the known genes encoding isoenzymes from Gram-negative Pseudomonas strains.

The influence of high phenol concentration on microbial growth

This investigation looked at the influence of high phenol concentrations (1000-1500 mg/l) on the growth yield of phenol degrading organisms in batch culture. The yield coefficient varied from 0.16 to 0.27. These values are considerably lower than those determined by others at lower phenol substrate concentrations. Although the conversion efficiency to biomass was low, the removal of phenol in terms of COD in the batch cultures was high (93.6% average). Present results did not show a relationship between yield and specific growth rate over the range 1000-1500 mg/l phenol. More work is required over a wider range of substrate concentration. With increasing phenol concentrations, the specific growth rate declined, consistent with Haldane inhibition kinetics.