ali akbar azimi

In drinking water treatments, for coagulation and sedimentation of suspended particles, several coagulants are used such as Alum, PAC and ferric chloride. In spite of their positive effect on turbidity removal, these chemicals cause some problems like corrosion and harmful by-products which result in bad effects on human and environmental health. Therefore, finding and using better and more effective materials without such adverse effects is a necessity. The aim of this research was to study the effect of chemically synthetized sodium ferrate (S.F.) in liquid state for the turbidity removal from Zayandehrud River in two conditions: normal turbidity (less than 100 NTU) and high turbidity (more than 900NTU). This research was performed in four states of 30×60, 40×60, 60×60, and 30×40; in each state, one of the water independent variables effective on water turbidity was changed. These four states were S.F. dosing rate, gentile mixing speed, rapid mixing time and pH. For the experiment design, analysis and optimization of independent variables effective on turbidity removal were used. In addition, the surface response method (RSM-D-Optimal) plus Design Expert-v10 optimization software were used for this study. Finally, in this research, according to the standard methods, the residual total Fe (due to sodium ferrate) was checked in the research in order to ensure that its value was in the allowable range for drinking water. The results showed optimum conditions as: pH of 8.5 and gentle mixing oscillating speed of 60rpm for 7min, 50rpm for 7min and 40rpm for 6min, (instead of 40rpm constant speed for 20min) and rapid mixing time of 30s with 120rpm (instead of  60s, which was conventional in Esfahan water treatment plant). In addition, the results showed that by using only 1.54mg/L of S.F. in the above-mentioned optimum condition, the water turbidity removal efficiencies were 95.17% and 99.07% for normal and high turbidity states, respectively. A comparison was made in this research between using S.F. and poly aluminum chloride (PAC) for both normal and high turbidity. The results showed the better effect of S.F. than PAC. The results also showed that the residual total Fe was in the allowable range before and after the filter (because of the reactivity of ferrate with Fe). From the results of this research, it can be concluded that using S.F. has a positive effect, technically and economically, on water turbidity removal (better effect than conventional chemicals) in both normal and high turbidity. Moreover, the results showed that residual total Fe remains in the allowable range.

The aim of this study is to reduce p-nitrophenol from wastewater using an SBR reactor for biological treatment of sewage and to study the effect of concentration of p-nitrophenol in wastewater on reduction of biomass production and sludge volume index. For this study, two SBR reactors with a volume of 20 liters with on-line control system were used. Once the stable conditions in the reactors are met, sampling and testing of parameters such as COD, MLSS, MLVSS, PH, DO, SV1, SOUR, and p-nitotrophenol (PNP), as well as the rate of reduction in production of biological solids were performed during the 12 months of research. The results showed that for the inserted amount of more than 100 mg/l of PNP, the COD decreased from 772 to 193 mg/l while the COD removal efficiency decreased to 75% and the PNP concentration decreased to 36.7 mg/l. The biodegradable solids decreased by about 49.5% relative to the control reactor. On the other hand, in this dose of PNP, the amount of SOUR was 31 mg O2/h, and VSS and the SVI value was less than 48 ml/g.  For the PNP dose of 150 mg/l, no biosolids was produced in the reactor but COD and PNP levels increased in the effluent. The presence of toxic organic compounds such as p-nitrophenol in high concentrations in the wastewater while reducing the removal efficiency of the organic matter decreases the biological solids and thus reduces the amount of excess sludge.

The compounds which contain nitrogen entering the environment can cause some problems, such as eutrophication for water resources and potential risk for human health because of methemoglobinemia and cancer. Biological techniques are effective in removing nitrate. The aim of this study was to remove nitrate from groundwater using denitrification. The main objectives of this research were determining the reduction of water nitrate based on different retention time and also the effect of using grape extract as organic matter and electron acceptor in biological nitrate removal from water.
In this experimental study, the effect of heterotrophic Pseudomonas separated from Shiraz wastewater treatment plant on removing nitrate from groundwater was investigated at pilot scale using grape extract as carbon source and filamentous media at constant pH (7±0.1) and temperature (20±1 °C). During this study, 2 pilots were made. Pilot number 1 was used for separation and growth of the above mentioned bacteria (Pseudomonas) that are able to remove nitrate. Pilot number 2 was also used for surveying the removal of nitrate by these bacteria. At least, 13 samples were examined in every retention time and each test was repeated for 2 or 3 times. Statistical analysis was performed in SPSS (ver.19) software using one-way repeated measures ANOVA, and Bonferroni tests.
According to the results, nitrate removal rates were 49%, 55%, 67% and, 67% at retention times of 1, 1.5, 2, and 2.5 hours, respectively. The best retention time was 2 hours with 67% removal rate (P The results showed that using grape extract as the carbon source and proper growth of bacteria in filamentous media led to a significant increase in the removal rate.

Background and Improper wastewater and solid waste management in rural areas could be a risk to human health and environment pollution. One percent of Iran’s rural area is connected to the wastewater collection network. Solid waste management in rural areas of Iran is mainly consisted uncontrolled dumping and open burning. The aim of this study is prioritization of wastewater and solid waste separate and combined management strategies in rural areas of Iran. This was a descriptive study. In this study, firstly were determined appropriate and conventional methods for wastewater and solid waste separate and combined management by using national and case studies. Then, using specified criteria and by applying a weighting system, prioritization was conducted and implementation strategies presented for wastewater and solid waste separate and combined management. The first priority for the collection and treatment, wastewater in rural areas are smalldiameter gravity systems and preliminary treatment with complementary treatment by land, respectively. In order to the rural solid waste management, organic compost complementary systems were in first priority. In the wastewater and solid waste combined management, the first priority was compost and biogas production by combining anaerobic UASB reactor and Chinese biogas. Considering for influence of various factors in selecting an appropriate method is very important in order to wastewater and solid waste separate and the combined management of a rural. Therefore, the accordance of presenting strategy with local conditions and facilities should be taken into consideration.

Heavy metals pollution is very important in Environment. Toxicity and accumulation characteristics of these metals are more noticeable for health aspects. Today, using bio-sorbent is more noticeable because these ways are ecofriendly and economic. In this survey, in addition to achieving Ni and Cd bio-sorption by bio-solid, the results of other relative surveys used for comparing the results and bio-sorption affinity discussion. Bio-solid powder produced from municipal excess sludge by drying, grinding and grainsizing. Ni and Cd solutions in 0.25 and 0.75 mille molar have been contacted which 0.5, 1, 2 and 4 grams of biosolid in pH 4, 200 rpm stirring, 24-260C temperature and two hours (continuous 5-420 min in kinetic study) time and samples have been analyzed with atomic absorption spectrophotometer to kinetic and isotherm modeling study and comparing the results. The maximum equilibrium adsorption of metals observed at two hours contact time and increasing of pH up to 4 increased the adsorption rate. The equilibrium data of both metals could be fitted by Langmuir isotherm equation and the maximum adsorption capacity (qmax) for cadmium and nickel are 0.38 and 0.195 mmol/gr dry bio-solid, respectively. The same as other biomasses studied for bio-sorption of heavy metals bio-sorption affinity of bio-solid for Cd is more than Ni. Generally, the bio-sorption affinity of algae and fungi for heavy metals bio-sorption is more than sludge and bacteria that is the result of cellular wall characteristics.

This study evaluated the efficiency of Electrical coagulation process in removal of COD, turbidity, detergent and phosphate from carwash effluent. An experimental study in laboratory scale was carried out and a glass tank with volume of 3 liters (effective volume of 2 liters) containing 4 electrode-page iron and aluminum (AL-AL, AL-Fe, Fe-Fe) were used. Electrodes were connected to a power supply with using bipolar method to convert alternative electricity to direct current. Daily samples were collected from different carwash effluents. Initial pH of samples were reported between 7 to 9.At first different tests were performed on primary samples. Percentage of removal was calculated in range pH and electrical potential of 11, 7, 3 and 30, 20, 10 volts respectively. Reaction times were set 90, 60, 30 minutes with middle intervals of 2 cm. The results showed the efficiency of COD removal in the optimum range of pH=3, voltage of 30 and retention time of 90 minutes with iron electrode was more 93% also the capacity of detergent removal for this process in optimum pH of 7, voltage of 30 retention time of 90 minutes with iron electrode was 94%. The highest phosphate and turbidity removal efficiency in pH of 7 after 90 minutes retention time, voltage of 30, with aluminum electrode reached more than 99%. According to the results obtained electrical energy consumption in aluminum electrodes was less than others. However aluminum is more expensive than iron and the difference in energy consumption between iron and aluminum can be ingnored. Apart from that COD and detergent removal efficiency of iron electrodes is higher than aluminum electrodes therefore, using iron as the electrode is more economical and recommended. Altogether it was found that this method can be use as a safe and convenient method for treating carwash effluent and according to the high removal efficiency of process, effluent can be discharged safely into the environment.

Many industrial & semi industrial countries manage to use SBR in order to industrial & municipal wastewater treatment. Simplicity, flexibility & being economical of this technical biological treatment, lead it to its significance in utilizing for treating of industrial & municipal wastewater.To study this procedure, two units of SBR reactor's cylinder made of poly glass with 20 liter volume are used. For seeding the reactors, artificial wastewater with COD of 600 mg/l & BOD of 600 mg/l is used. Reactors with different solid retention time (SRT) (5, 10, 15, 20 & 25 days) are operated.After providing the steady state in the reactors, during 8 months research, sampling and testing parameters such as COD, BOD, MLSS, MLVSS, MLNVSS, pH, DO, SVI, SOUR & F/M were done.The results show that SRT (5, 10, 15, 20 & 25 days) for 10 days duration is the best results for COD removal efficiency without existence of any bulking, pin point flocks and also foaming & dispersed growth difficulties. In this SRT duration, the amount of SVI has been up to 90 mg/l. This SRT system has been used in growth phase and the amount of F/M is 0.25. In the SRT less than 5 days, inorganic material removal & sludge volume index efficiency (SVI=215 mg/l) due to voluminous foaming generation & also fine coagulation generation resulted from lowness MLSS and dispersed growth occurrence respectively was low and it which shows that the system was operated in log growth phase & the amount of F/M has been1.8. Also in the SRT more than 25 days filamentous bulking phenomenon was aggravated and system efficiency due to bad sludge settle ability (SVI=215 mg/l) was low & because of over growth of filamentous bacteria, sludge can not be settled easily.With the increasing of SRT (more than 20 days), due to entrancing to declining phase and increase of inactive & old bacteria, the rate of oxygen consumption & SOUR reached to 7(mgo2/hr/grVSS), however in a low SRT (5 days), due to entrancing log growth phase & increase of active & young bacteria, the rate of oxygen consumption increased & SOUR reached up to 22 (mgo2/hr/grVSS).

Background and 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. Pilot operation indicated that the principal factors in implementing subsurface flow wetland were temperature, non-penetrateability of the bed, and wastewater ingredients. However, pretreatment and bed obstruction were the limiting parameters of the wetland maintenance. 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.

The efficiency of particle settling in tube settlers can be improved by reducing tube diameter; however, this has limits due to the clogging at low diameters. In this study, effect of reduced tube diameters on enhanced efficiency of tube settlers was investigated. This improvement was achieved by staging of the operation and reducing tube diameter in the last stage of the multi-stage tube settlers. Theoretical analysis indicated that the efficiency of tube settlers would improve if tube settlers were used in different stages in series and that if their diameter was reduced in the last stage. The predictions from the theoretical analysis were tested in a pilot study. One- and two-stage tube settler pilot plants were used to remove water turbidity caused by clay in the first and second phases of tests with and without adding coagulant, respectively. The tube diameter in the one-stage tube settler were 5.0 cm, and those in those the first and second stages of the two-stage tube settler was 5.0 and 1.2 cm, respectively. The results of both phases showed that the two-stage tube settler was more efficient than the one-stage for turbidity removal with no clogging observed because the majority of the particles had been removed in the first stage.

The excessive biological sludge production is one of the disadvantages of aerobic process such as SBR. So the problem of excess sludge production along with its treatment، and disposal in aerobic processes in municipal and industrial waste water can be seen in many parts of the world even in our country. to solve the problem of excess sludge production، reducing in by oxidizing some of the sludge by Ozone is a suitable idea، thus reducing the biomass coefficient as well as the sewage sludge disposal. In this study، Two SBR reactors with of 20 liter being controlled by on-line system are used. After providing the steady state in the reactors، along the 8 month research sampling and testing parameters such as COD، MLSS، MLVSS، DO، SOUR، SVI، residual ozone and Yield coefficient were done. The results showed that during the solid retention time of 10 days the kinetic coefficient of Y and Kd was 0. 58 (mg Biomass / mg COD) and 0. 058 (1/day) respectively. At the next stage of research، different concentrations of ozone in one liter of the returned sludge to reactor were used to reduced the excess biological sludge production. The results showed that the 20 mg ozone per gram of MLSS in one liter of the returned sludge to reactor is able to reduce Yield coefficient from 0. 58 to 0. 28 (mg Biomass/mg COD)، In other words، the biological excess sludge by 52 %. but the soluble COD increased slightly in the effluent and the removal percentage decreased from 92 in blank reactor to 64 in test reactor. While the amount of SVI and SOUR in this consumed ozone concentration reduced 9 mgO2/h. gVSS and 20 ml/g respectively. No sludge was seen in the 25 mg ozone concentration per gram of MLSS in one liter of the returned sludge to reactor.