Comparison Of Different Advanced Oxidation Processes Degrading P-Chlorophenol In Aqueous Solution

In present study, degradation of p-chlorophenol using several oxidation systems involving advanced oxidation processes such as ultraviolet/H2O2, microwave/H2O2 and both in the absence of hydrogen peroxide in batch mode by photolytic pilot plant and modified domestic microwave oven was evaluated. The oxidation rate was influenced by many factors, such as the pH value, the amount of hydrogen peroxide, irradiation time and microwave power. The optimum conditions obtained for the best degradation rate were pH=7 and H2O2 concentration of 0.05 mol/L for ultraviolet/H2O2 system and pH=10.5, H2O2 concentration of about 0.1 mol/L and microwave irradiation power of about 600W for microwave/H2O2 system at constant p-chlorophenol concentration. The degradation of p-chlorophenol by different types of oxidation processes followed first order rate decay kinetics. The rate constants were 0.137, 0.012, 0.02 and 0.004/min1 for ultraviolet/H2O2, microwave/H2O2, ultraviolet and microwave irradiation alone. Finally a comparison of the specific energy consumption showed that ultraviolet/H2O2 process reduced the energy consumption by at least 67% compared with the microwave/H2O2 process

Effects Of 4-Chlorophenol Loadings On Acclimation Of Biomass With Optimized Fixed Time Sequencing Batch Reactor

Chlorinated phenols in many industrial effluents are usually difficult to be removed by conventional biological treatment processes. Performance of the aerobic sequencing batch reactor treating 4- chlorophenol containing wastewater at different loadings rates from 0.0075 to 1.2 g4CP/L.d was evaluated. The sequencing batch reactor was operated with fill, react, settle and decant phases in the order of 10:370:90:10 min, respectively, for a cycle time of 8 h at 10 days solid retention time and 16 h hydraulic retention time in the stable period. The effects of 4-chlorophenol loadings on the 4- chlorophenol and chemical oxygen demand removal percents, yield coefficient (Y), biomass variation and sludge volume index were investigated. High chemical oxygen demand removal efficiencies (95±3.5%) and approximately complete 4-chlorophenol removal (>99%) were observed even in the absence of growth substrate. The degradation of 4-chlorophenol led to formation of 5-chloro-2-hydroxymuconic semialdehyde, which was more oxidized, indicating complete disappearance of 4-chlorophenol via metacleavage pathway. A compact sludge with excellent settleability (sludge volume index=47±6.1 mL/g) developed during entire acclimation period. High removal efficiencies with sequencing batch reactor may be due to enforced short term unsteady state conditions coupled with periodic exposure of the microorganisms to defined process conditions which facilitate the required metabolic pathways for treating xenobiotics containing wastewater

Feasibility of an Anaerobic Baffled Reactor (ABR) In Treating Starch Industry Wastewater

The anaerobic baffled reactor (ABR) includes a mixed anaerobic culture separated into compartments and a novel process with a series of vertical baffles at each compartment. It dose not require granulation for its operation, resulting in shorter start-up time. In this study, the feasibility of the ABR process was investigated for the treatment of wheat flour starch wastewater. Simple gravity settling was used to remove suspended solids from the starch wastewater and used as feed. Start-up of a reactor (13.5L with five compartments) using a diluted feed of approximately 4500 mg/L chemical oxygen demand (COD) was accomplished in about 9 weeks using seed sludge from the anaerobic digester of a municipal wastewater treatment plant. The reactor with a hydraulic retention time (HRT) of 72 h at 35°C and an initial organic loading rate (OLR) of 1.2 kgCOD/m3.d showed a removal efficiency of 61% COD. The best reactor performance was observed with an organic loading rate of 2.5 kgCOD/m3.d (or hydraulic retention time of 2.45 d) when a COD conversion of 67% was achieved. The main advantage of using an ABR comes from its compartmentalized structure. The first compartment of an ABR may act as a buffer zone to all toxic and inhibitory materials in the feed and, thus, allows the later compartments to be loaded with a relatively harmless, more uniform, and mostly acidified influent. In this respect, the later compartments would be more likely to support active populations of the relatively sensitive methanogenic bacteria

PERFORMANCE EVALUATION OF AN ANAEROBIC BAFFLED REACTOR TREATING WHEAT FLOUR STARCH INDUSTRY WASTEWATER

Feasibility of the anaerobic baffled reactor process was investigated for the treatment of wheat flour starch wastewater. After removal of suspended solids by simple gravity settling, starch wastewater was used as a feed. Start-up of a reactor (with a volume of 13.5 L and five compartments) with diluted feed of approximately 4500 mg/L chemical oxygen demand was accomplished in about 9 weeks using seed sludge from anaerobic digester of municipal wastewater treatment plant. The reactor with hydraulic retention time of 72h at 35°C and initial organic loading rate of 1.2 kgCOD/m3.d showed 61% COD removal efficiency. The best performance of reactor was observed with an organic loading rate of 2.5 kgCOD/m3.d or hydraulic retention time of 2.45 d and the COD conversion of 67% was achieved. The system also showed very high solids retention with effluent suspended solids concentration of about 50 mg/L for most organic and hydraulic loadings studied. Based on these observations, the ABR process has potential to treat food industrial wastewater as a pretreatment and is applicable for extreme environmental conditions

Innovative anaerobic upflow sludge blanket filtration combined bioreactor for nitrogen removal from municipal wastewater

In this research, a novel laboratory scale anaerobic/upflow sludge blanket filtration combined bioreactor was designed and operated to improve the efficiency of the upflow sludge blanket filtration process for the simultaneous removal of phosphorus and nitrogen from wastewater. The anaerobic/upflow sludge blanket filtration technique was developed by adding an anaerobic reactor to its influent and operated by varying the main process parameters in order to gain the optimum conditions. The results showed that biological removal efficiency of nitrogen and preservation of sludge blanket strongly depend on wastewater characteristics, hydraulic retention time, sludge age and process controlling parameters. The combined bioreactor performed a total nitrogen removal efficiency of 96.6 % with the sludge age of 25 days, total hydraulic retention time of 24 h and optimum "chemical oxygen demand/nitrogen/phosphorus" ratio of 100/5/1. This ratio also improved the compaction quality of sludge blanket in the upflow sludge blanket filtration clarifier. The average specific nitrification and denitrification rates occurred during the process can be expressed as 4.43 mg NOx-N produced/g VSS.d and 5.50 mg NOx-N removed/g VSS.d at the optimum ratio, respectively. To avoid sludge rising due to denitrification process, the optimum total hydraulic retention time of 16 to 24 h was achieved based on the effluent quality. This study suggested that the anaerobic/upflow sludge blanket filtration bioreactor at the optimum operational conditions can be an effective process for removal of nutrients from municipal wastewater

The assessment of suture spacing on the esthetic and functional outcomes of skin closures in different age groups

Abstract Background and Aims Dermatological surgeons must master the factors affecting wound healing. Suturing is the most common method of wound closure. One of the significant factors in suturing that affects wound healing and cosmetic results is the distance between sutures, which has been studied very little to date. The aim of the current study was to investigate the effect of simple interrupted suture with a distance of 2 and 5 mm on the esthetic and functional results of suture closure in different age groups. Methods In patients with two skin lesions, one wound was sutured with a distance of 2 mm and the other with a distance of 5 mm, and the wounds were evaluated 1 and 3 months after the operation using the POSAS scale. Results Patients' opinions indicate that, in the suture intervals of 2‐ and 5‐mm and at 1 and 3 months, the average was lower in the younger group than it was in the older group and also, as per the physician's opinion, the average in the age group under 50 years was significantly lower than that in the age group over 50 years. Conclusions According to the results of the present study, a suture of 2‐mm and a suture of 5‐mm would result in different esthetic and functional outcomes depending on the patient's age. The average in the age group less than 50 years was significantly lower than that of the age group greater than 50 years

Detection Of Phenol Degrading Bacteria And Pseudomonas putida In Activated Sludge By Polymerase Chain Reaction

Phenol is one of the organic pollutants in various industrial wastewaters especially petrochemical and oil refining. Biological treatment is one of the considerable choices for removing of phenol present in these wastewaters. Identification of effective microbial species is considered as one of the important priorities for production of the biomass in order to achieve desirable kinetic of biological reactions. Basic purpose of this research is identification of phenol-degrading Pseudomonas Putida in activated sludge by polymerase chain reaction (PCR) that has high speed and specificity. In this research, 10 various colonies of phenol-degrading bacteria were isolated from municipal activated sludge and the rate of phenol removal and growth rate of these bacteria were assessed in different concentrations of phenol (200 – 900 mg/L). Confirmation of the largest subunit of multicomponent phenol hydroxylase (LmPH) gene and gene coding the N fragment in Pseudomonas Putida-derived methyl phenol operon (DmpN gene) through PCR were used for general identification of phenol-degrading bacteria and Pseudomonas Putida, respectively. Presence of a 600 bp (base pairs) bond in all of isolated strains indicated that they contain phenol hydroxylase gene. 6 of 10 isolated bacteria were Pseudomonas Putida because they produced a 199 bp PCR product by DmpN primers. According to PCR results in this study, the best phenol-degrading bacteria that can utilize 500 – 600 mg/L phenol completely after 48 hours incubation, belong to Pseudomonas Putida strains. It is clear that use of isolated bacteria can lead to considerable decrease of treatment time as well as promotion of phenol removal rate