[Treatment and kinetic of synthetic wastewater containing beta-naphthol by nano titanium oxide coated on activated carbon]

Many industrial effluent plants contain amounts of hard biodegradable compounds such as beta-naphthol which can be removed by conventional treatment systems. The objective of this research is to treat wastewater containing naphthalene by nano titanium oxide coated on activated carbon. Photocatalytic experiments were carried out for different concentrations of beta-naphthol using time and pH as dependent factors. Nano TiO2 coated on activated carbone in one liter batch reactor and the resultants compounds' concentration were measured in a photocatalytic reactor with UV-C of 12 Watt. The experimental results indicated that UV/ nano TiO2 coated on activated carbone removed 92% of beta-naphthol with concentrations of 100 mg/L within an overall elapsed time of three hours. beta-naphthol total removal with concenteration of 25 mg/L was observed in two hours. UV/ nano TiO2 process is very fast and effective method for removal of beta-naphthol and pH 11 was indicated as the optimum pH

Role of moving bed biofilm reactor and sequencing batch reactor in biological degradation of formaldehyde wastewater

Nowadays formaldehyde is used as raw material in many industries. It has also disinfection applications in some public places. Due to its toxicity for microorganisms, chemical or anaerobic biological methods are applied for treating wastewater containing formaldehyde.In this research, formaldehyde removal efficiencies of aerobic biological treatment systems including moving bed biofilm [MMBR] and sequencing batch reactors [SBR] were investigated. During all experiments, the efficiency of SBR was more than MBBR, but the difference was not significant statistically. According to the results, the best efficiencies were obtained for influent formaldehyde COD of 200 mg/L in MBBR and SBR which were 93% and 99.4%, respectively. The systems were also capable to treat higher formaldehyde concentrations [up to 2500 mg/L] with lower removal efficiency. The reaction kinetics followed the Stover-Kincannon second order model. The gram-positive and gram-negative bacillus and coccus as well as the gram-positive binary bacillus were found to be the most dominant species. The results of [13]C-NMR analysis have shown that formaldehyde and urea were converted into N-[[[aminocarbonyl] amino] methyl]urea and the residual formaldehyde was polymerized at room temperature

[Investigation of amount and effective factors on trihalomethane production in potable water of Yazd]

Yazd province is located in the central desert part of Iran in which water scarcity was one of the most important problems. This has been recently solved to some extent, due to the approved channel project of water transferring from Isfahan to Yazd. Chlorination is usually used in the last stage of water treatment for disinfection in the networks, treatment plants, storages and channel stations. The possibility of carcinogen lateral composites formation is expected by tri-halo-methanes [THMs] due to the reactions occurs between the natural organic materials and free chlorine available in water. Based on the established standard by the country, the permissible limit of THMs in water is 200 mg/L. In this research, in addition to the amount of THMs and their distribution in Yazd water transferring channel and the city water network system, the important parameters and their correlations with THMs formation were discussed. In a year of sampling period, the concentrations of THMs including the four major components of chloroform, bromoform, bromo di-chloro methane and di-bromo chloro methane during all seasons were measured using gas chromatograph and analyzed. This was done for 11 stations including Zayande-rood Basin River and Isfahan water treatment plant up to Yazd Shehneh storage, stations and inline equalization tanks and also five regions of Yazd city network. According to the results, the maximum rate of THMs [51.14 mg/L] during the sampling period in summer for Yazd city network and in ancient context of Jamea Mosque district was found. In addition, the minimum concentration of THMs was 1.60 mg/L in winter for the domestic network of the city which was related to Azad Shahr district. The Average total amount of THMs during sampling periods in all stations was 12.26 mg/L. SPSS and Excel softwares were used to analyze the research data in the descriptive and inferential manner. Both statistical methods [Simple correlation coefficient, Pearson and Spearman correlation test]] with 5% significant level were considered for data analysis. The results indicated that no significant difference existed between these parameters and national and international standard scales. These rates were generally desirable and lower than standard limit which indicates acceptable operation in the treatment system and storages in the channel line of Isfahan to Yazd. Furthermore, it was obtained that there is a correlation between THMs rates and effective parameters in producing confidential values such as 95%and 99% for the residue chlorine and heat respectively. Finally the distribution and diffusion plan of THMs in transferring line and civic network of Yazd were drawn

[Investigation of PHA polymer production from sludge of municipal wastewater treatment plant and its effect on sludge volume reduction]

Owing to the fact that the major environmental problem is production of surplus sludge in wastewater treatment plant, reducing the volume of produced sludge was objective of this research. An anaerobic-aerobic SBR with working volume of 10 L was used to make micro-organism adapted and a polymer production reactor [PPR] with working volume of 1.5 L was used for producing polymer munisipal wastewater which contained different concentration of volatile fatty acids was consodered as the feed source [acetate and propionate] and this system was evaluated with SRT of 5, 7 and 10 days. The maximum polymer production efficiency observed within 5 days [SRT=5 days] though this efficiency was not significant in comparison with the two others time courses study. In this research the maximum polymer production efficiency at optimum condition was 25% of the sludge dry weight. Experiment revealed that producing polymer from activated sludge reduced the volume of sludge and the maximum reduced sludge volume was obtained 19%

Performance of aerated submerged fixed-film bioreactor for treatment of acrylonitrile-containing wastewater

Acrylonitrile is used as the main raw material for manufacturing acrylonitrile butadiene styrene resin. It is usually found as pollutant in the petrochemical wastewater. In this research an aerated submerged fixed-film reactor was developed to treat a synthetic acrylonitrile butadiene styrene unit wastewater containing acrylonitrile. Laboratory experiments were conducted using a bioreactor with 44.2 L capacity operated at different hydraulic and organic loading rates. Stationary submerged biofilms were attached to net-type media [polypropylene] under diffused aeration. The specific surface area and porosity of media were 324 m[2]/m[3] and 87%, respectively. In the first phase the reactor was operated in hydraulic retention times of 9, 7, 5 and 4 h with soluble chemical oxygen demand of 300 mg/L. Then the experiments were continued with the constant retention time of 4 h and variable chemical oxygen demand concentrations of 350, 400 and 450 mg/L. In stable condition of operation and loading rates of 0.8 to 2.4 kg/m[3]d the removal efficiencies of reactor for soluble chemical oxygen demand reached to 95 to 99%. At the organic loading rate up to 2.4 kg/m[3]d the soluble chemical oxygen demand was less than 50 mg/L which was lower than the Iranian national discharge standards [chemical oxygen demand<60 mg/L]. The increase of organic and surface loading to 2.7 kg/m3d and 23.16 g/m[2]d, respectively, caused the system becoming unstable and the soluble chemical oxygen demand removal efficiency decreased to 66%. Finally, the kinetic coefficients of the aerated submerged fixed-film reactor for treating of acrylonitrile were determined using a separate pilot unit. According to the results, it was concluded that the aerated submerged fixed-film reactor can be used as suitable approaches for treating of petrochemical effluents contain acrylonitrile

[Investigation of nitrogen removal efficiency from wastewater using modified anaerobic baffled reactor [MABR]]

Nitrogen compounds in wastewater are mainly in four types of organic, ammonia, nitrite and nitrate. Total nitrogen concentration in municipal wastewater is usually within 25 to 45 mg/L as nitrogen. The most important problem with nitrogen is its oxygen demand and human health effect. Anaerobic Baffled Reactor [ABR] is a system in which baffles are used to direct wastewater flow. During 9 months study, a 15 liter modified ABR [104*30*15 cm] with eight baffled compartments was used for nitrification-denitrification processes. In the seventh compartment, the wastewater was aerated to oxidize ammonia to nitrite and nitrate. Denitrification was done in the first four compartments with removal efficiency from 60 to 84 percent for nitrite and nitrate, respectively. During the shock loading study [4 times of the last influent], a sharp decrease in nitrogen removal rate was observed which was then returned to the previous efficiency after 11 days. Artificial neural network was used to evaluate and process the data in which the observed error in 10 patterns was less than 15 percent. Anaerobic baffled reactor with an influent of up to 200 mg/L has capability to remove total nitrogen concentration to less than the standard level of Iranian Department of Environment of 50 mg/L as nitrate and 10 mg/L as nitrogen

[Reaction kinetics of aniline synthetic wastewater treatment by moving bed bioflim reactor]

Experiments were conducted to investigate the behavior of Moving Bed Bioflim 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. 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. 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. MBBR as an advanced biological process had a proper COD removal efficiency for the biological treatment of aniline wastewater compared to other researchers methods

Isolation and characterization of a novel native bacillus strain capable of degrading diesel fuel

The ability of native bacteria to utilize diesel fuel as the sole carbon and energy source was investigated in this research. Ten bacterial strains were isolated from the oil refinery field in Tehran, Iran. Two biodegradation experiments were performed in low and high [500 and 10000 ppm, respectively] concentration of diesel fuel for 15 days. Only two isolates were able to efficiently degrade the petroleum hydrocarbons in the first test and degraded 86.67% and, 80.60% of diesel fuel, respectively. The secondary experiment was performed to investigate the toxicity effect of diesel fuel at high concentration [10000 ppm]. Only one strain was capable to degrade 85.20% of diesel fuel at the same time [15 days]. Phenotype and phylogeny analysis of this strain was characterized and identified as dieseldegrading bacteria, based on gram staining, biochemical tests, 16S rRNA gene sequence analysis. These results indicate that this new strain was Bacillus sp. and could be considered as Bacillus Cereus with 98% 16 S rRNA gene sequence similarity. The results indicate that native strains have great potential for in situ remediation of diesel-contaminated soils in oil refinery sites

[USBF performance in treating sugar industries wastewater]

Upflow Sludge Blanket Filtration [USBF] system is a modification of the conventional activated sludge process that incorporates an anoxic zone with an upflow sludge blanket filtration clarifier in one bioreactor. It has no inherent capacity limits and is used in a wide range of applications in municipal, industrial and agricultural wastewater treatment. The main objective of this study was to evaluate the performance of a continuous USBF reactor for the treatment of sugar industrial wastewater. Sixty liter laboratory pilot scale plant was made of plexiglass consists of 14 liter anoxic zone, 38 liter aerobic zone and 8 liter clarifier. Used molasses for raw wastewater was obtained from Varamin Sugar Company. During the study, the wastewater has been initially fed to anoxic zone of the bioreactor. It mixed with recycled activated sludge returned from the clarifier and the mixed liquor entered into aerobic zone of the bioreactor. From aeration zone, the mixed liquor passed through the sludge zone at the bottom of the clarifier which was then separated by upflow sludge blanket filtration and then the clear water discharged from the system. To complete the internal circulation loop, collected activated sludge at the bottom of the clarifier was recycled to the anoxic zone. Experimental studies indicated that average removal efficiency of COD with HRTs from 21 to 26 hours in the aerobic zone and from 8 to 10 hours in the anoxic zone were from 77 to 97 percent depended on input feed [1000 to 30000 mg/L]. USBF as an advanced biological process had a proper COD removal efficiency for the biological treatment of sugar industries wastewater compared to other researchers methods

Biodegradation of aromatic amine compounds using moving bed biofilm reactors

Three moving bed biofilm reactors were used to treat synthesized wastewater of aromatic amine compounds including aniline, para-diaminobenzene and para-aminophenol that are found in many industrial wastewaters. The reactors with cylindrical shape had an internal diameter and an effective depth of 10 and 60 cm, respectively. The reactors were filled with light expanded clay aggregate as carriers and operated in an aerobic batch and continuous conditions. Evaluation of the reactors' efficiency was done at different retention time of 8, 24, 48 and 72 h with an influent COD from 100 to 3500 mg/L [filling ratio of 50%]. The maximum obtained removal efficiencies were 90% [influent COD=2000 mg/L], 87% [influent COD=1000 mg/L] and 75% [influent COD=750 mg/L] for aniline, para-diaminobenzene and para-aminophenol, respectively. In the study of decrease in filling ratio from 50 to 30 percent, 6% decrease for both para-diaminobenzene and para-aminophenol and 7% increase for aniline degradation were obtained. The removal efficiency was decreased to about 10% after 15 days of continuous loading for each of the above three substrates. In the shock loading test, initially the COD removal rate was decreased in all reactors, but after about 10 days, it has been approached to the previous values. Finally, biodegradability of aromatic amines has been proved by nuclear magnetic resonance system

Degradation of aromatic compounds using moving bed biofilm reactors

For biological treatment of water, there are many different biofilm systems in use. Examples of them are trickling filters, rotating biological contactors, fixed media submerged biofilters, granular media biofilters and fluidized bed reactors. They all have their advantages and disadvantages. Hence, the Moving Bed Bioflim Reactor process was developed in Norway in the late 1 980s and early 1990s to adopt the best features of the activated sludge process as well as those of the biofilter processes, without including the worst. Two cylindrical moving bed biofilm reactors were used in this study working in upflow stream conditions. Experiments have been done in aerobic batch flow regime. Laboratory experiments were conducted at room temperature [23-28°C] and synthetic wastewater comprising a composition of phenol and hydroquinone in each reactor as the main organic constituents, plus balanced nutrients and alkalinity were used to feed the reactor. The ratio of influent to effluent COD was determined at different retention times. The results indicated that the removal efficiency of each selected compound is affected by the detention time. At low phenol and hydroquinone concentration [from 700 to 1000 mg/L] maximum removal efficiency [over 80%] was obtained. By thither increasing in COD loading rate up to 3000 mg/L, a decrease in COD removal rate was occurred. In the reactor containing pyrogallol in COD of 1500 mg/L, the removal rate decreased to 10 percent because of its toxicity for microorganisms

Particulate polycyclic aromatic hydrocarbons in Urban Air of Tehran

Polycyclic Aromatic Hydrocarbons are ubiquitous in the urban atmosphere and one of the most atmospheric pollutants to be identified as suspected carcinogens .The objective of this study was to compare particulate PAH profiles from several sites across Tehran. Atmospheric concentrations of Polycyclic Aromatic Hydrocarbons in Tehran were evaluated to study particulate PAH profiles in different sites. The particles size distributions were unimodal with a fine mode diameter [PM<0.49 micro m]. Five sites were selected in residential areas and one site in rural area for representing various situations and role of motor vehicles in producing Polycyclic Aromatic Hydrocarbons. Organics on the filter were extracted with acetonitrile and a group of 16 Polycyclic Aromatic Hydrocarbons was selected for evaluation. PAH identification was done by High Performance Liquid Chromatography. Total PAH concentration associated with particles collected on the six-stage cascade impactor stages and after-filter in different sites ranged between 0.132 to 234.3 ng/m[3]. The mean concentrations of Polycyclic Aromatic Hydrocarbons, collected on each stage were: 4.17 ng/m[3] for PM[10-7.2] micro m, 5.69 ng/m[3] for PM[7.2-3] micro m, 11.95 ng/m[3] for PM[3-1.5] micro m, 9.18 ng/m[3] for PM[1.5-0.95] micro m, 2.82 ng/m[3] for PM[0.95-0.49] micro m and 47.91 ng/m[3] for PM < 0.49 micro m respectively

Interaction's effect of organic material and aggregation on extraction efficiency of TPHS from petroleum contaminated soils with MAE

Microwave-Assisted Extraction [MAE] is a type of low-temperature thermal desorption process that its numerous advantages have caused a wide spread use of it. Microwave heating is a potentially attractive technique as it provides volumetric heating process to improve heating efficiencies as compared with conventional techniques. The ability to rapidly heat the sample solvent mixture is inherent to MAE and the main advantage of this technique. Presently MAE has been shown to be one of the best technologies for removing environmental pollutants specially PAHs, phenols and PCBs from soils and sediments. Five different mixtures and types of aggregation [Sand, Top soil, Kaolinite] besides three concentrations of crude oil as a contaminant [1000, 5000 and 10000 mg/L] were considered. The results indicated that regardless of aggregation, the presence of humus component in soil reduces the efficiency. Minimum and maximum efficiencies were for sandy soil [containing organic components] and kaolinite [without any organic content], respectively. According to the results of this research when some amount of humus and organic materials are available in the matrix, it causes the extraction efficiency to perform as a function of just humus materials but not aggregation. Increasing the concentration of crude oil reduced the efficiency with a sharp steep for higher concentration [5000-10000 mg/L] and less steeper for lower concentration [1000-5000 mg/L]. The concentration of the contaminant, works just as an independent function with extraction time and aggregation factors. The extraction period of 10 min. can be suggested as an optimum extraction time in FMAE for PAHs contaminated soils

Use of sequencing batch reactors [SBRs] in treatment fiber wastewater

Wood fiber industries are producing large amounts of wastewater, which are discharged into the environment everyday. This type of wastewater with high pollution potential in suspended solids, COD and color, are required to be treated before entering to the receiving environment. North part of Iran is covered by huge land of forests. Several pulp and paper industries are located in the area. One of these industries is Iran Wood Fiber Company in which many researches have been done in both laboratory and pilot scale by the main author in recent years. One of the studies was to investigate the Sequencing Batch Reactors [SBRs] efficiency for treating the wastewater. Considering parameters such as influent COD, detention time, nutrient concentration, and their effects on COD, turbidity and total solids removal efficiency of the system, four serial SBRs in laboratory scale were investigated. The results of the system with 10 hours detention time, 1000-2500 mg/L COD and 100:5.1:1 C/N/P had the best efficiency with 92, 84, 52% removal for COD, turbidity and total solids, respectively. Pilot scale plant studies using SBRs were also done in the company. The results indicated good removal efficiencies that also discussed in this paper