Feasibility of utilizing moving bed biofilm reactor to upgrade and retrofit municipal wastewater treatment plants

In this study, feasibility of upgrading and retrofitting municipal wastewater treatment plants was investigated at laboratory scale using Moving Bed Biofilm Reactor [MBBR] process. For this purpose, an aerobic pilot was operated for nearly one year in different conditions, in which a moving bed carrier with a specific biofilm surface area of 500 m[2]/m[3] and a filling rate of 60% was utilized. System efficiency in removal of BOD[5] and COD was examined at different hydraulic retention times [HRTs] of 1, 1.5, 2, 2.5, 3 and 4 h. The obtained results indicated high ability of the system to tolerate organic loading and to remain stable at a high food to microorganism [F/M] ratio. The system produced effluents with good quality at low HRTs and led to an average BOD[5] removal efficiency of nearly 88% during the operational period. The Organic Loading Rate [OLR] applied to the system had a range of 0.73-3.48 kgBOD[5]/m[3].day and 2.43-11.6 gBOD[5]/m[2].day, at which the reactor showed a good performance and stability. In general, it was concluded that [MBBR] can be an excellent alternative for upgrading and optimizing municipal wastewater treatment plants

Study on high-strength anaerobic landfill leachate treatability by membrane bioreactor coupled with reverse osmosis

One of the most important concerns in Tehran municipal landfill is the production of leachate and its potential for water resources pollution, this study was undertaken to examine feasibility of biological and physico/chemical treating of high-strength landfill leachate that was collected from Tehran municipal landfill. Average COD of the leachate in aerobic submerged membrane bioreactor is 68000 mg/L. The reactor with a working volume of 175 L, having membrane module [Hollow fiber] with pore size of 0.1 microm coupled with reverse osmosis with pore size of 0.001 micron was used in this study. The dissolved oxygen [DO] concentration was maintained at 3.2 mg/L and solid retention times [SRTs] and hydraulic retention times [HRT] were controlled at 55 and 15 days respectively, the average Membrane Bioreactor effluent COD was 1733 mg/L with average removal efficiency of 97.46%. The average NH4 -N removal efficiencies was 99%. On the other hand, an almost complete nitrification was achieved during this period. PO[4] -P concentration in the effluent was low and its average removal efficiency was as high as 90%; especially during the operation period. The averages reverse osmosis [RO] effluent COD was 335 mg/L with average removal efficiency of 99.13%. PO[4]-P concentration in the RO effluent was 0.86 mg/L and its average removal efficiency was 99.33%. The use of Membrane technologies, more especially reverse osmosis offers the best solution of achieving full purification with average COD removal efficiency of 99% and solving the problem of water resources pollution

DI-[2-ethylhexyl] phthalate oxidative degradation by fenton process in synthetic and real petrochemical wastewater

Di-[2-Ethylhexyl] phthalate [DEHP] belongs to the class of phthalate esters and is used as an additive in many products including plastics, paints and inks or as a solvent in industrial formulations. The degradation of DEHP in aqueous solution using oxidative Fenton reaction [H[2]O[2]/Fe[2+] was carried out in this study. It was found that H[2]O[2] concentration, Fe[2+] concentration, and pH were the three main factors that could significantly influence the degradation rates of DEHP. The highest degradation percentage [85.6%] of DEHP was observed within 60 min at pH 3 in H[2]O[2]/Fe[2+] system. The results of our study suggested that the concentration with 90 mg/L H[2]O[2] 5 mg/L Fe[2+], and 20 mg/L DEHP in the solution at pH 3 were the optimal conditions. The optimized reaction parameters were preceded for treatment of real wastewater obtained from a petrochemical plant

Legal criteria and executive standards of solid waste disposal subjected to solid waste management act

This research work attempts to compare the legal and technical criteria of locating household and municipal landfills and discuss them along with legal and technical principles. For this purpose, it was attempted to discuss and compare the related most important national and international standards. Due to say, employing the legal standards of locating household and municipal landfills in corporation with managerial decision making is considered as the most significant issues. Thus, selection of evaluation legal methods of and weighting the criteria of locating the landfills were technically investigated. The main landfill location of Tehran [Kahrizak] was investigated in order to analyze the analytical hierarchical process of its impacts resulted from environmental problems along with the legal aspects of the main landfill site's by the means of Delphi, AHP and Expert Choice techniques, in conflict with the rules adopted from waste act, enacted executive guidelines and content of the published references on Guidelines of Department of the Environment. Ultimately, regarding the questionnaires, recommendations of the learnt and through the items resulted from investigation and analysis of hierarchical process; the following 4 conclusions were achieved: 1] Education and discipline of people as well as the authorities who enforce the rules; 2] Investigation and amendment of Waste Management Act clauses; 3] Receiving the costs of waste management from waste producers and 4] Setting up waste exchange market to utilize the wastes economically. Considering the results [investigation and amendment of Waste Management Act clauses] was selected and recommended as the best option. As a result of further technical investigations on the Waste Management Act, the necessity of employing the criteria of impact evaluation in amending the clauses of Waste Management Act was also recommended

[Investigating the hygiene of anzali drinking water resources for corrosion and precipitation potentials using corrosion indexes]

Corrosion is a physical and chemical reaction occurring between a substance and its surrounding environment leading to the change in the substance properties. Nowadays, corrosion has become one of the biggest issues in water quality control and can financially damage the water pipes and other water transmission and distribution installations. In addition, the penetration of heavy metal into water as a result of corrosion can be a threat to the consumers' health conditions. Because of such negative health effects, regular chemical quality control of water seems mandatory. To investigate the corrosion or precipitation potentials of drinking water in Anzali, which is supplied by Guilan water treatment plant and deep water wells. To do so, parameters including pH, temperature, calcium hardness, alkalinity and Total Dissolved Solid [TDS] were measured and based on their values, four indices including Langelier Saturation Index, Ryzner Saturation Index, Aggressive index and Pokurious index were determined. As revealed, the average values for Langelier Saturation, Ryzner Saturation, Aggressive and Pokurious indices were respectively[-0.89], [9.29], [12.4] and [8.82]. The results of the present study indicate that Anzali water resources have corrosion potential and are corrosive and thus can threaten the consumers' health status in the long term

Role of metal species in flocculation rate during estuarine mixing

Flocculation can be considered as an effective mechanism in self-purification of metals during estuarine mixing. In the present investigation, flocculation of metals during mixing of Minab River water with the Strait of Hormuz [The Persian Gulf] water is studied for the first time. Flocculation behavior of metals [except for Pb] is governed by dissolved organic carbon. The source of dissolved organic carbon is terrigenous in the estuarine waters of study area. The general pattern of flocculation of studied metals is manganese [180 micro g/L] > zinc [88 micro g/L]> nickle [73 micro g/L]> copper [30 micro g/L]> lead [19 micro g/L]. The results of present study show that metal species are a very important factor in overall flocculation rate. It is found that solids and oxides have the highest and lowest flocculation levels, respectively. Eh-pH diagram indicated that lead is present as lead oxide in Minab River water and the least flocculation rate is attributed to this element. The results also showed that flocculation rate of metal species could be as solids > free ions = hydroxides > oxides. The amount of metal flocculation is about 30.5, 6.6, 25.3, 10.4 and 62.5 ton/y for zinc, Pb, Ni, Cu and Mn, respectively

Investigation of using fixed activated sludge system for removing heavy metals [Cr, Ni and Pb] from industrial wastewater

The operation of fixed activated sludge system for treatment of wastewater containing heavy metal compounds [chromium, lead and nickel], by using of fixed activated sludge [FAS] system is studied in this research. A Plexiglas tank consisted of three sections including a downward-flow aerated reactor, an upward-flow aerated reactor and a gravity sediment unit, fed with the synthetic wastewater. The results showed that COD removal efficiency in the FAS is about 96% and the acclimation time for microorganisms is short. While chromium, lead and nickel removal efficiency in the fixed activated sludge at concentration of 1 mg/lit. is 84%, 75% and 80%, respectively, by increasing concentration of them to 5 mg/lit, the removal percentage increased to 90%,84% and 87%, respectively. When concentration of chromium, lead and nickel increased to 10 mg/lit, the removal efficiency became 85%, 95% and 92%, respectively. Concentration of heavy metals [chromium, lead and nickel] at 50 mg/lit; caused the removal efficiency of 86%, 96% and 95.1%, respectively. By rising concentration of heavy metals up to 100 mg/lit, the removal ratio efficiency became 86%, 97.6% and 97%, respectively. At each stage, increasing of heavy metal concentration [chromium, lead and nickel] caused to decreasing of COD and MLSS removal efficiency at the beginning of period but COD and MLSS removal efficiency re-increased by micro-organisms acclimation to changes. However this increase is less than best previous stage condition of COD removal efficiency and showed a downward trend. Therefore, heavy metal compounds removal in the fixed activated sludge is not just a biological process, indeed some part of these compounds are removed by adsorption on sludge. Altough this part is negligible in comparison with biological removal of these compounds. Heavy metals which are found in the sewage of many industries like petrochemical industries, refinary plants, paper mills and chemical industries, disrupt the wastewater treatment plants performance by affecting microorganisms and synthetic reactions due to their toxicity. Consequently, the concentration of these compounds exceed the maxiJIlum contamination level [MCL] in the effluent of wastewater treatment plants and causes many health and environmental problems. Since the ability of some microorganisms for degrading of heavy metal compounds are proved, biological treatment is widely used for removing heavy metals from industrial wastewaters. Bioreactors with fixed activated sludge beds are one of suitable methods in this subject. In this research, the performance of activated sludge bioreactors with fixed beds is reviewed for removal of three heavy metal compounds i.e. chromium, lead and nickel in industrial wate waters. Fixed activated sludge system [FAS] is a composition of activated sludge system and trickling filter which media are used for forming biofilms in the aeration tank to enhance the treatrnnet performance. A synthetic solution is prepared to provide a wastewater with a COD of 550-600 mg/L

[Determination of the design parameters for making urban wastewater plants in cold regions of Iran]

Indicating the quantities and qualitative characteristics of raw wastewater entering treatment plant is one of the basic fundamentals of correct1 designation of treatment plants. The purpose of this study was to determine the design parameters for making urban treatment plants in cold regions of Iran. This applicative research is based on empirical studies which have descriptively been done in a temporal manner. In this study, three wastewater plants were selected as pilot from cold regions of Chaharmahal va Bakhtiari province i.e. Shahrekord, Broujen and Farsan wastewater plants. The quantative and qualitative characteristics of waste water entering to these wastewater plants were analyzed in a one-year period. In this research as well as measuring the waste water flow entering the plant the temperature, PH in entrance, chemical oxygen demand [COD], 5-days Biochemical oxygen demand [BOD5], suspended Solids [TSS], volatile suspended solids [VSS], Kajaldal Nitrogen [TKN] and phosphate phosphorous [P] were measured in 24-hours compound samples proportional to the wastewater flow. Data were analyzed using t-test and ANOVA. The final results of the research parameters in cold weather regions for BOD5, COD, TSS, VSS, TKN and P has daily been 41, 60, 65, 47, 8.3, and 0.93gr per capita. Average production of wastewater was found 177 liter per capita per day. The obtained results from Max and Min wastewater flow coefficient were 1.76 and 0.29, respectively. No significant differences were found for BOD5, COD, TKN and P between three wastewater plants, but TSS, VSS were significantly higher in Shahrekord [P<0.05]. In the case of using design parameters based on different climates and real characteristics of waste waters, we can obtain higher efficiency in guidance of exploitation from wastewater plants. In order to design plants in cold weather regions like Shahrekord [and most cities in the west of Iran] it is recommended that the per capita production and other design parameters to be considered in the trust range of this research

Improring the performance of Pars oil refinery wastewater treatment system

This study aims to inspect the performance of the wastewater treatment system of the Pars Oil refinery. Quantity and quality of wastewater are determined through samplings and measurements. The performance of system is evaluated considering total suspended solids, total dissolved solids, phosphate, chemical oxygen demand, biochemical oxygen demand, ammonia nitrogen, furfural, oil and pH. For precise comparing the qualitative and quantitative parameters, the wastewater entering the refinery is sampled four times from different places like boilers and from their channels, oil wastewater channels, and solvent wastewater channels. Despite some reforms that has been applied to the treatment system in order to reach the environmental standards, the system cannot treat the wastewater to the discharge standards. From the results of this research the advanced Membrane Bioreactor system for complementary refining along with optimized oil elimination system from wastewater is suggested

Nanofiltration process on dye removal from simulated textile wastewater

Dyestuffs removal from industrial wastewater requires special advanced technologies, since dyes are usually difficult to remove by biological methods. In this study nanofiltration process was used for removal of different dyestuffs from solutions. The rate of dye removal by spiral wound nanofiltration membrane in film thin composite MWCO=90 Dalton, was evaluated for four classes of dyes acidic, disperse, reactive and direct in red and blue dyes medium. Dye absorbance was measured by spectrophotometric method [2120 Standard Method 1998]. Effects of feed concentration, pressure and total dissolved solids concentration were also studied. Results showed that increasing dye concentration lead to higher color removal up to 98% and at different pressures for acidic and reactive blue were up to 99.7%. Different types of dyes had no effect on dye removal and permeate flux. During 2 h. of the operation time, permeate flux decline was increased. Permeate fluxes for different types of red dyes were from 16.6 to 12.6 [L/m[2]/h.] and for blue dyes were from 16.6 to 10.45 [L/m[2]/h.]. Presence of sodium chloride in dye solutions increased dye rejections nearby 100%. Chemical oxygen demand removal efficiencies for reactive blue, disperse blue, direct and disperse red dyes were also approximately 100%

Comparison of adsorption process by GAC with novel formulation of coagulation-flocculation for color removal of textile wastewater

This study evaluates the effectiveness of adsorption process by Granular Activated Carbon [GAC] compared with a novel formulation of coagulation - flocculation process for dye removal from textile wastewater. In this regard, acidic, reactive, disperse and direct red dye are used to prepare the synthetic dye. Dominant wave length for each dye is determined by spectrophotometeric method. Using GAC as adsorbent, equilibrium time and adsorption isotherm of each dye are determined with aid of spectrophotometric method. The results show that GAC can not remove dispersed red dye. Acidic red, direct red and reactive red of 5 mg/L concentration are removed by GAC up to 90%, 88% and 43% in 30, 60 and 120 min. [equilibrium time] respectively. Dyes of 50 mg/L concentration are removed up to 93%, 30% and 51% in 15, 90 and 150 min. respectively. Adsorption obeys Freundlich isotherm for acidic red, BET isotherm for direct red and Langmuir isotherm for reactive red. This investigation presents a novel formulation of coagulation - flocculation for color removal from textile dye solutions and illustrates its efficiency. Novel formulation of coagulation - flocculation remove direct red, reactive red and disperse red of 5 mg/L concentration respectively up to 93%, 91.3% and 57.1%. Also the mentioned dyes of 50 mg/L are removed respectively up to 90.8%, 91.9% and 70.1%

study of feasibility for water purification using vertical porous concrete filter

There is a need to find cheaper and simpler techniques for rural water filtration system in developing countries. Using a filter made of blocks for the water treatment enables one to make vertical filters. It is expected that the amount of land utilized would decrease by more than 70% if vertical filters were used. The operation and washing would be simpler than using horizontal sand filters as filters made of blocks would be used instead. The feasibility study focused on finding adequate materials, compositions and methods of making a block with enough resistance to water pressure, sufficient porosity for water transformation, and using inexpensive, readily available materials. A pilot study was used to determine an appropriate thickness. Testing the porous filter in another pilot study using the low overflow rate of river water showed biological growth in that media and an adequate efficiency of about 90-100% was obtained for decreasing the coliform bacteria. Washing in this filter is possible. The amount of water necessary for backwashing is 2.9% of total amount of water, which is passed

Physicochemical and biological treatability studies of urban solid waste leachate

In this research, physical, chemical and biological treatability of Tehran solid waste leachate was studied. Results indicate that the amount of COD for the fresh raw leachate of Tehran is equal to 66,608 mg/l. The leachate is transferred to an equalization tank for storage and pH control process. After neutralization, leachate is introduced to an up flow and down flow anaerobic reactor. The effluent of anaerobic reactor is conducted to a sequencing batch reactor. Sequence batch reactor [SBR] effluent was pumped in to sand and activated carbon filters, after chemical coagulation and clarification. Results showed that anaerobic reactor with detention time of 3 days had a 35% COD removal and increasing the detention time to 4.5 days would improve the COD removal to 45%. Nutrient adjustment with phosphorus and nitrogen increased the initial 23% efficiency of sequence batch reactor to 44%. The effluent COD of SBR reactor was 21,309 mg/l. Recycling of aerobic reactor effluent with incoming feed to anaerobic reactor reduced the anaerobic reactor influent COD to 20,000 mg/l and this caused 53% and 57% COD removal in the anaerobic and aerobic effluent, respectively. The total systems COD performance increased to 80% and SBR effluent COD eventually reduced to 4,000 mg/l. Coagulation, flocculation and sedimentation processes were practiced to make the 4,000 mg/l effluent COD comply with environmental standards of Iran. The optimum coagulant found to be ferric chloride with the dosage of 50 mg/l at pH of 12, which reduced 10% of COD to an amount of 3,676 mg/l. The effluent was stored in a tank and then pumped in to pressure sand filter and afterwards to activated carbon filter. The COD removal was three and 90% for sand and activated carbon filters, respectively. The total process reduced the remaining COD to 36 mg/l, which is in compliance with environmental standards of Iran