IRANIAN JOURNAL OF HEALTH AND ENVIRONMENT
Year:2009 | Volume:2 | Issue:1 (3)|Papers Count:8

Backgrounds and Objectives: in recent years, mobile bed biological reactors have been used progressively for municipal and industrial wastewaters treatment. Dissented experiment is a trial that significant changes will accrue for influent variables in the process, and generally used for identification of the effective factors and optimization of the process. The scope of this study was determination of the optimized conditions for the MBBR process by using of Taguchi method.Materials and Methods: Reactor start up was done by using of the recycled activated sludge from Ahwaz wastewater treatment plant. After that and passing the acclimation period, with hydraulic residence time equal to 9 hours matched for 1000, 2000 and 3000 mg/l based on COD respectively, for optimization determination of the acclimated microbial growth, the variables change (pH, nitrogen source, chemical oxygen demand and salinity) were determined in 9 steps, and all of the results were analyzed by Qualitek -4 (w32b).Results: In this study, organic load removal based on COD was 97% and best optimized condition for MBBR were (inf. COD=1000 mg/l, pH=8, salinity=5% and the Nitrogen source=NH4CL).Conclusion: Based on our finding, we may conclude that Taguchi method is on of the appropriate procedure in determination the optimized condition for increasing removal efficiency of MBBR.

Backgrounds and Objectives: Direct biodegradation of landfill leachate is too difficult because of high concentrations of COD and NH3 and also the presence of toxic compounds. The main objective of this study was to application of Strurvite precipitation as a pretreatment stage, in order to remove inhibitors of biodegradation before the batch decant activated sludge process with addition of powdered activated carbon (PAC).Materials and Methods: Strurvite precipitated leachate was introduced to a bench scale batch decant activated sludge reactor with hydraulic retention times of 6 and 12 hour. PAC was added to aeration tank directly at the rate of 3.5 g/L.Results: TCOD, SCOD, NH3 and P removal efficiency with addition of PAC in HRT of 6 h were 90, 87, 98.3 and 94 % respectively and 96, 95, 99.2 and 98.7 5 in HRT of 12 h.Conclusion: According to obtained data from this work, it can be concluded that Strurvite precipitation before batch decant activated sludge process and simultaneous addition of PAC is promising technology for leachate treatment and can meet effluent standards for discharge to the receiving waters.

Background and Objectives: Microorganisms including Fungi, are among air-transmitted infectious agents at hospitals and patient care settings, which in addition to patients, can afflict Health Care Workers (HCWs) and visitors, and may results in extravagant economic burden and impact on human health. Use of nanotechnology and especially nanosilver particles is one of the methods which are used in infection control. This article is the result of a research project investigating nanosilver painting effect on bioburden of indoor hospital air.Materials and Methods: The study was aimed to assess antifungal effects of nanosilver painting. Three rooms were selected at the infectious diseases ward of Imam Khomeini hospital complex. Two of the rooms were painted with two brands of nanosilver paints provided from two separate companies (as cases), and the third room with non-nanosilver paint brand (as control).Results: Air sampling was carried out using a portable air pump (Quick Take 30) at pre-planned schedule Each Sampling was done in two minutes with the rate of 28.3 Liter per minute. Samples were transferred on Sabourauds Dextrose Agar culture, to count the colonies of fungal based on Colony Forming Unite (CFU/m3). Results were analyzed by ANOVA method.Conclusion: Active sampling method was not able to show statistically significant reduction in the total fungal bioburden between the control and case rooms. In evaluating the time trend of the nanosilver paints effect, sampling measures revealed that nanosilver paints had statistically significant effect in fungal bioburden reduction in the first third ( i.e. first month) of the study period.

Backgrounds and Objectives: Today, One of the most important environmental issues is solid waste Produced in Dentistry That because of the presence of hazardous, toxic and pathogen agents has special importance. In this survey, solid waste produced in Hamadan Dentistry laboratories and practical dentist offices is studied.Materials and Methods: In this descriptive study, from 24 Dentistry laboratories in Hamedan 5 offices and from 27 practical dentist offices 5 offices were selected in simple random way. From each offices 3 sample at the end of successive working day (Sunday, Monday and Tuesday) were analyzed. Samples were manually sorted into different 41 components and by means of laboratory scale were measured. Then, measured components were classified based on characteristic and hazardous potential.Results: Total annual waste produced in Dentistry laboratories and practical dentist offices in Hamaden is 15921.79 and 8677.56 Kg respectively. Production percentages of domestic type, chemical and pharmaceutical waste, potentially infectious and toxic wastes in practical dentist offices were 91.14, 6.7, 2.14 and 0.02 respectively. Dentistry laboratories solid waste comprises of 94.47 percent domestic type and 5.53 percent chemical and pharmaceutical waste. Main components of produced analyzed wastes were 2 components that consist of more than 80 percents of total dental solid waste. So, waste reduction, separation and recycling plans in the offices must be concentrated on these main components.Conclusion: In order to waste suitable management, it is suggested that in addition to educate waste producer for waste reduction, separation and recycling in the offices, each section of dental waste (toxic, chemical and pharmaceutical, potentially infectious and domestic type wastes) separately and according to related criteria are managed.

Background and Objectives: Phenolic compounds are presence in many industrial wastewaters, and have been classified as priority pollutants. Application of several conventional processes due to high cost and low efficiency has been limited. Thus, new methods such as enzymatic polymerization seem to be preferable and effective processes with high potential to substitute the conventional processes.This study was carried out to evaluate Raphanus sativus extract as a peroxides enzyme source for polymerization and removal of phenol from synthetic wastewater in the presence of hydrogen peroxide.Materials and Methods: The study was performed in batch reactor at room temperature. Peroxidase enzyme was extracted from Raphanus sativus plant roots. Primary concentration of phenol in wastewater was 1000 mgl-1. The concentration of phenol and enzymatic activity was been measured by photometric assay.Results: The results show that Raphanus sativus extract is a suitable source of peroxidase enzyme. Mean enzymatic activities in this extract was 3.107 Uml-1. Also, our results showed that elevation of extract volume lead to high efficiency of phenol removal, in which the increase in the extract volume from 5 to 50 ml, resulted in the efficiency of processes increased from 7.6 to 98.2%. Also, sequencing addition of H2O2 and extract has improved the effects. The phenol removal efficiency of the reaction time after 3 h with single and three stages adding of reactants was 84.2 and 93.1%, respectively.Conclusion: Enzymatic polymerization can be used as an appropriate process for the removal of phenolic compounds from wastewaters. To meet the optimized condition in process, the ratios of phenol/ enzyme and H2O2/ phenol and sequences of the adding of reactants should be considered.

Background and Objectives: Propylene glycol is the main compound of anti-freezing chemicals. A significant amount of propylene glycol is released to the environment after application and contaminates the soil. The main objective of this study was to determine the biological removal of propylene glycol from wastewater and its degradation in soil by the isolated bacteria from activated sludge process.Materials and Methods: In the present study, the sludge taken from the return flow in a local activated sludge treatment system was used as the initial seed. The performance of the bioreactor in treating the wastewater was evaluated at four different retention times of 18, 12, 6 and 4 h all with the inlet COD concentration of 1000 mg/L. This phase lasted around 4 months. Then, a part of the adapted microorganisms were transported from the bioreactor to the soil which was synthetically contaminated to the propylene glycol.Results: The average of propylene glycol removal efficiency from the wastewater in detention times of 18, 12, 8 and 4 h in steady state conditions was 98.6%, 97.1%, 86.4% and 62.2% respectively. Also, the maximum degradation in soil was found to be 97.8%.Conclusion: According to the results obtained from this study, it appears that propylene glycol is inherently well biodegradable and can be biodegraded in liquid phase and soil after a short period of adaptation.

Backgrounds and Objectives: Now a days modified activated sludge ways are used for standard removing nutrient substances from waste water that is named Enhanced biological phosphorus removal One of the most suitable ways is Anoxic-Oxic (A/O) process. The goal of this research is investigation and solving existing problems of Khoy power plant (P.P) waste water treatment plant (WWTP) and optimizing of phosphorus removal in it.Materials and Methods: This research is done full scale in this treatment plant. The treatment plant was operating with extended aeration process, and some problems had, so in the first stage with in investigation of total efficiency, problems and their reasons determined. In the second stage after operational modifications existing problems was solved and real efficiency of treatment plant particularly for phosphorus (P) removal determined. In the third stage changes, system converted to A/O process and new system was tested with Changing parameters like food/microorganism (F/M), return sludge ratio (RAS) and sludge retention time (SRT).Results: In the first stage the most important problems were over concentration of BOD, TSS, and P in effluent of treatment plant and overgrows of alga observed in parts of treatment plant and effluent receiving conduit. The main reason of high concentration of P was considered releasing of sludge. In the second stage operating condition modification efficiency of P removal increased from 50 to 62 percent. In the end of third stage value of P removal reached to %82 and the most suitable of anoxic contact time was determined 3 to 4 hours, SRT terry day and F/M ratio o.12, that the most effective change has been the decrease of SRT to three days.Conclusion: Adjusting of operating factors like SRT, RAS, sludge processing way in WWTP can increase P removal in them with in total efficiency remaining, such as in this case it was %12. In waste water treatment particularly for P removal the A/O process is suitable so in this project its effect on P removal efficiency has been %20.

Background and Objectives: Experiments were conducted to investigate the behavior of Moving Bed Biofilm Reactor (MBBR) as a novel aerobic process for treatment of aniline synthetic wastewater as a hard biodegradable compound is commonly used in number of industrial processes. The objective of this paper is evaluation of MBBR in different conditions for treatment of aniline and determination of reaction kinetics.Materials and Methods: In the MBBRs, different carriers are used to maximize the active biofilm surface area in the reactors. In this study, the reactor was filled with Light Expanded Clay Aggregate (LECA) as carriers. Evaluation of the reactor efficiency was done at different retention time of 8, 24, 48 and 72 hours with an influent COD from 100 to 3500 mg/L (filling ratio of 50%). After obtaining removal efficiencies, effluent concentration of aniline was measured by adsorption spectrum and maladaptive municipal wastewater treatment plant sludge in batch conditions for confidence of aniline biodegradation and its adsorption to the sludge mass.Results: The maximum obtained removal efficiencies were 91% (influent COD=2000 mg/L) after 72 hours. Biodegradation of aniline in MBBR has been also approved by NMR spectrum tests. Finally experimental data has indicated that Grau second order model and Stover-Kincannon were the best models to describe substrate loading removal rate for aniline.Conclusion: MBBR as an advanced biological process had a proper COD removal efficiency for the biological treatment of aniline wastewater compared to other researchers methods.