Application of nano-electrode platinum [Pt] and nano-wire titanium [Ti] for increasing electrical energy generation in microbial fuel cells of synthetic wastewater with carbon source [Acetate]

The microbial fuel cells [MFCs] are a kind of systems through which the anaerobic bacteria along with the oxidation of simple or complicated organic matter in the wastewater can generate the electric power. This is a modern approach used in generation of the clean and renewable energy. In this research, two pilot laboratories of double-chamber microbial fuel cells were made. One of them contained platinum electrode and simple nano-wire Titanium and the other had nano-electrode Platinum and nano-wire with equal volume of 1 liter. They were launched in 4 Hydraulic Retention Time [2.5, 3.5, 4.5 and 5.5 hrs.] and increased in 4 steps of organic loading rate with synthetic wastewater with carbon source [acetate] and temperature [20 +/- 5°C]. The voltage and electric current was measured by means of digital multimetre. The performance of the two reactors in generation of electricity was investigated based on the polarization curve. Maximum voltage and current output were, respectively, 1425 mV and 13.1 mA, and the maximum power density and current density were, respectively 78 mW/nr and 67.3 mA/m[2] and columbic efficiency were achieved in 34.6% in reactor with nano-electrode Platinum and nano-wire Titanium [in HRT 4.5 hr and external resistance was 10[KT]. In addition, the maximum removal rate of COD in organic loading rate 3.99 Kg COD/m day is equal to 98.28% for nano-electric and nano-wire and 72.5% for simple electrode and wire

An investigation on the role of flocculation processes in geo-chemical and biological cycle of estuary [case study: gorganrood river]

The present investigation provides a thorough study of eliminating soluble and colloidal .elements of copper, iron, magnesium and zinc during estuarine mixing of Gorganrood River water with Caspian Sea water in Iran. The processes of flocculation were carried out in 10 aquariums in order to furnish the salinity in an interval of 0.3 - 4.4 ppt. The obtained result is indicative of non- conservative behavior of studied metals. Higher flocculation resulted in a lower salinity and vice-versa. The obtained results indicated that most metal were eliminated during the initial mixing of fresh water with sea water at 0.6 - 1.0 ppt salinity interval. The trend of flocculation rates of elements in the river were obtained as follows: Fe [97.33%]> Mn [91.66%] >Zn [72.72%] > Cu [52.63%].The annual average elimination of soluble elements of iron [Fe]. Manganese [Mn], zinc [Zn] and copper [Cu] from Gorganrood river to Caspian Sea decreases from 1040.68, 59.1498, 302.26, 263.64 tons per year to 27.75, 124.88, 83.255, 124.88 tons per year, respectively. According to the cluster analysis, parameters such as salinity, temperature, electrical conductivity, Eh and suspended solid materials do not have any impact on flocculation of elements. The only parameter that influences the flocculation of elements is the pH. This research illustrates that estuarine processes are effective mechanisms in self- purification of heavy metals from water resources. Metal speciation studies that are carried out by Eh-pH software show that studied metals are present as solid [in case of Cu], free ions [Fe and Mn] and finally hydroxides [Zn]

Procedures of starting up and implementing of subsurface wetlands

Background and Purpose: Subsurface flow wetlands are one of the successful treatment methods used for municipal and industrial wastewater treatment, and are economical in terms of energy consumption and workforce. Much research has been conducted on wetland operation output in wastewater treatment, but no enough information is available on their start-up and maintenance. The present study investigates the circumstance of starting up and implementing a wetland

Methods and Materials: In this experimental study, two subsurface flow wetlands with a two-day detention time and two pretreatment units were built. The former was similar to Primary Settling tank with a 4-hour detention time and the latter was similar to anaerobic pond equipped a with digestion pit with a two-day detention time in a pilot scale. The wastewater [BoD5 = 250 mg/l, Tss=320 mg.l and ph=7.2] from municipal network in Sabzevar, Iran was used for irrigation; the pilot implementation and maintenance took one year

Results: Pilot operation indicated that the principal factors in implementing subsurface flow wetland were temperature, nonpenetrateability of the bed, and wastewater ingredients. However, pretreatment and bed obstruction were the limiting parameters of the wetland maintenance

Conclusion: Pretreatment of the subsurface flow of wetlands does not yield a high output; and if anaerobic ponds equipped with digestion pits are used, the treatment output is significantly enhanced, and the wetland operation will face minimum barriers

Selection of wastewater treatment process based on the analytical hierarchy process and fuzzy analytical hierarchy process methods

This paper presents an application of the analytical hierarchy process and fuzzy analytical hierarchy process methods for selecting the best wastewater treatment process. The analytical hierarchy process is one of the best ways for deciding among the complex criteria structure in different levels, and the fuzzy analytical hierarchy process is a synthetic extension of the classical method when the fuzziness of the decision makers are considered. After reviewing aerobic treatment processes operated in Iran's industrial estates and determining the main criteria used for treatment process evaluation, they are arranged in a hierarchy structure. Selection of the best wastewater treatment process is a multi-criteria decision making problem. Conventional methods are inadequate for dealing with the imprecise or vague nature of linguistic assessment. To overcome this difficulty, the fuzzy analytical hierarchy process is proposed for dealing with the vagueness of decision makers' judgments. The alternatives consist of extended aeration, absorption bio-oxidation, integrated fixed-film activated sludge, sequencing batch reactor, aerated lagoon. Based on the general condition of industrial estate's wastewater treatment plants, technical/administrative, economic and environmental criteria and their sub-criteria are weighted and then criteria evaluated and priorities of alternatives have been done by analytical hierarchy process and fuzzy analytical hierarchy process methods by the use of triangular fuzzy numbers. Finally, selection of the best process and ranking of these five processes are carried out by these foregoing methods, and some sensitivity analyses are conducted to show the results' sensitiveness to the changes of the weights of the evaluation criteria

Removal of triethylamine vapor from waste gases by biotrickling filter

Sampling of triethylamine in the cold-box unit in an auto-manufacturing company in Iran has indicated the average concentration of 430 mg/m[3] in the emission duct. In this study a biotrickling filter was used for treatment of triethylamine in air stream. Triethylamine removal efficiency [K/L] pattern was evaluated by changing volumetric loading [L], superficial gas velocity [U[o]], empty bed gas retention time [EBRT] and recirculation liquid flow rate [V[L]], while operating at constant temperature of 25 +/- 1 Degree C. For finding the effect of EBRT on the triethylamine removal efficiency, tests were performed at EBRT of 156 s, 52s and 31s and a constant liquid recirculation velocity of 3.466 m[3]/m[2]/h. Results showded that for a test period of 65 days, triethylamine removal efficiencies of more than 98% were obtained for EBRT of 156s and loading rates of less than 48 g/m[3]/h. With an EBRT of 52s removal efficiencies of > 90% were obtained for loadings of < 57 g/m[3]/h and maximum removal capacity was 53.4 g/m[3]/h at volumetric loading of 64 g/m[3]/h. Also with an EBRT of 31 s the maximum removal capacity was 53.6 g/m[3]/h at volumetric loading of 68 g/m[3]/h. Thus in the range of implemented EBRTs the proper absorption of triethylamine from gas to liquid phase took place and the elimination efficiency was shown to be dependent on microorganisms activity rate. The effect of liquid flow rate on the triethylamine removal efficiency was investigated by changing VL in the range of 3.46 to 10.40 m[3]/m[2]/h at EBRT=31 s and influent triethylamine concentration of 600 mg/m[3]. Results showed that the triethylamine removal efficiency was nearly independent of the liquid recirculation rate

Evaluation of spatial and seasonal variations in surface water quality using multivariate statistical techniques

In this study, spatial and seasonal variations of water quality in Haraz River Basin were evaluated using multivariate statistical techniques, such as cluster analysis, principal component analysis and factor analysis. Water quality data collected from 8 sampling stations in river during 4 seasons [Summer and Autumn of 2007, Winter and Spring of 2008] were analyzed for 10 parameters [dissolved oxygen, Fecal Coliform, pH, water temperature, biochemical oxygen demand, nitrate, total phosphate, turbidity, total solid and discharge]. Cluster analysis grouped eight sampling stations into three clusters of similar water quality features and thereupon the whole river basin may be categorized into three zones, i.e. low, moderate and high pollution. The principle component analysis/factor analysis assisted to extract and recognize the factors or origins responsible for water quality variations in four seasons of the year. The natural parameters [temperature and discharge], the inorganic parameter [total solid] and the organic nutrients [nitrate] were the most significant parameters contributing to water quality variations for all seasons. Result of principal component analysis and factor analysis evinced that, a parameter that can be significant in contribution to water quality variations in river for one season, may less or not be significant for another one

Kinetic analysis of enhanced biological phosphorus removal in a hybrid integrated fixed film activated sludge process

Hybrid integrated fixed film activated sludge is a promising process for the enhancement of nitrification, denitrification and phosphorus removal in conventional activated sludge systems that can be used for upgrading biological nutrient removal, particularly when they have space limitations or need modifications that will require large monetary expenses. In this research, successful implementation of hybrid integrated fixed film activated sludge process at temperate zone wastewater treatment facilities has been studied by the placement of fixed film media into aerobic, anaerobic and anoxic zones. The primary objective of this study was to investigate the incorporation of enhanced biological phosphorus removal into hybrid integrated fixed film activated sludge systems and study the interactions between the fixed biomass and the mixed liquor suspended solids with respect to substrate competition and nutrient removal efficiencies. A pilot-scale anaerobic-anoxic-oxic configuration system was used. The system was operated at different mean cell residence times and influent chemical oxygen demand/total phosphorus ratios and with split influent flows. The experimental results confirmed that enhanced biological phosphorus removal could be incorporated successfully into hybrid integrated fixed film activated sludge system, but the redistribution of biomass resulting from the integration of fixed film media and the competition of organic substrate between enhanced biological phosphorus removal and denitrification would affect performances. Also, kinetic analysis of the reactor with regarding to phosphorus removal has been studied with different kinetic models and consequently the modified Stover-Kincannon kinetic model has been chosen for modeling studies and experimental data analysis of the hybrid integrated fixed film activated sludge reactor

Investigation of intermittent chlorination system in biological excess sludge reduction by sequencing batch reactors

The excessive biological sludge production is one of the disadvantages of aerobic wastewater treatment processes such as sequencing batch reactors. To solve the problem of excess sludge production, oxidizing some of the sludge by chlorine, thus reducing the biomass coefficient as well as the sewage sludge disposal may be a suitable idea. In this study, two sequencing batch reactors, each with 20 L volume and controlled by on-line system were used. After providing the steady state conditions in the reactors, sampling and testing of parameters were done during 8 months. The results showed that during the solid retention time of 10 days the kinetic coefficient of Y and Kd were 0.58 mg biomass/mg COD and 0.058/day, respectively. At the next stage, different concentrations of chlorine were used in the reactors intermittently. Results showed that 15 mg chlorine/gMLSS in the reactor was able to reduce the yield coefficient from 0.58 to 0.3 mg biomass/mg COD. In other words, the biological excess sludge was reduced about 48%. But the soluble chemical oxygen demand increased slightly in the effluent and the removal percentage decreased from 95% in the blank reactor to 55% in the test reactor

Fate of intermediate biodegradation products of triethyl amine in a compost-based biofiltration system

Biofiltration of Triethylamine [TEA] vapor used as a catalyst in casting operations was evaluated in this study. The unit consisted of a 6-L three-stage biofilter containing a mixture of compost and wood chips [40:60 v/v] as the filter medium. Seed microbial population from municipal activated sludge was acclimated for a period of three weeks prior to the actual experimental runs. In the startup period, high pH values up to 10 was observed due to alkaline nature of TEA and inadequate formation of biofilm and low overall biodegradation. Steady increase of organic-N concentration along with gradual upward trend of pressure drop indicated sound establishment of microbial population. Operational parameters studied included loading rate [6-116 g/m[3]/h], hydraulic detention times [40-60 s], temperature [30 +/- 1°C], and humidity [50-55%]. Results indicated effluent ammonia concentrations meeting standards of 25 ppm can be obtained after 2.5 months of operation. Optimal organic loading rates [OLRs] of 90 +/- 14 g/m3/h for Hydraulic Retention Time [HRT] value of 48 s were suggested. Under these conditions, elimination capacity of 71 +/- 3 g/m3/h and removal efficiency 81 +/- 14% were achieved. Mass balance was performed on different forms of nitrogen products for a constant inlet concentration of 180 ppm TEA with a relatively stable removal efficiency of about 90% maintained for over a month. Both liquid [leachate] and gas [different sections, inlet, and outlet] phase measurements were made for the purpose of performing calculations. Ammonium- N and Nitrate-N were dominant in the first and third sections of the reactor, respectively. Cumulative TEA-N mass balance over a 2-month period indicated an equal proportion breakdown into ammonia- N, nitrate-N, and ammonium and organic-N. The fact that up to 30% of TEA-N could not be accounted for in the leachate and gas measurements can be attributed to incorporation into the cellular constituents

Natural and human-Induced impacts on coastal groundwater

Groundwater is the main source of potable water in most areas of Mazandaran province, like Sari and Babol city. Thus the safety of groundwater supplies is very important in these regions. Unfortunately attention to groundwater quality has remained limited in Iran. In recent years, the growth of industry, technology, population, and water use has increased the stress upon both land and water resources of Mazandaran province. The main pollutants of groundwater in Mazandaran province are domestic, industrial and agricultural wastewater discharges. In addition, contribution of municipal and rural solid wastes in deterioration of groundwater quality of the Mazandaran province is considerable. The quality of several water wells in Mazandaran province was investigated in this research. In tested water wells, the concentrations of Cu, Cr, Zn and NO3 are within WHO standard limits, but Pb, Se and Cd concentrations are often exceeding the WHO maximum permissible standard values. Results show that the current quality of groundwater in Mazandaran province does not present immediate health related concerns. However, the quality of water wells in Mazandaran province is not reliable because of relatively high rate of various pollutants discharges into groundwater resources. Consequently, establishment of both monitoring programs and appropriate regulations to minimize uncontrolled discharges into groundwater resources is ecessary for conservation of this valuable source of water supply in Mazandaran province

Evaluation of the quality and self purification potential of Tajan River using Qual2E model

Tajan River is among significant rivers of Caspian Sea water basin. Pollution sources that threaten the quality of water in Tajan River may be classified in to two categories namely point and non-point sources. Major pollutants of latter category are Mazandaran wood and pulp, Paksar dairy products and Sari Antibiotic production factories, as well as 600-dastgah residential area. On the other hand, non-point sources whose waste is considered as a distributed load consist of Sari municipal wastewater and agriculture-related pollutants that are drained towards the river. In order to model the quality of river flow, Qual2E model is taken in to consideration. Considering TDS, the river quality is completely acceptable in cold seasons. However, in spring and summer the value of this parameter is increased and this causes some restrictions in the use of this water for irrigation of specific sensitive crops. Agricultural activities and consequent irrigated waters are the major causes of higher reported TDS values in warm seasons. Current status of DO is completely acceptable and this is highly related to the relative high value of width on depth ratio along the river. BOD and COD locate in a fairly poor condition. Quality deterioration is more noticeable in cold seasons. Higher rate of precipitation and consequent greater runoff generation towards the river basin justify the relative increase of mentioned parameters in fall and winter. Generally, non-point pollution sources are more contributed in deterioration of Tajan River water quality