The use of anaerobic processes for treatment of strong wastewater has been increasing in recent years. Among these processes Upflow Anaerobic Sludge Blanket (UASB ) and Upflow Anaerobic Fixed Bed(UAFB- or anaerobic Bio-Filter) reactors have attracted more attention. This research was carried out to investigate the performance of this system for treatment of sugar wastewater.
Three equal size UAFB bioreactors filled with different size and type of packing were used for experimentation in this study. Some of the most important results are classified as:
Reactors were very sensitive to alkalinity. Best results were obtained when alkalinity was kept at 3000 mg/l by addition of lime and sodium bicarbonate. As expected, temperature had a marked effect on the performance of the reactors, COD reduction was 40% higher at 37° C compared to 24° C.
The reactors performed well up to feed concentrations of 16000 mg/l at 20 hours retention period. It became clear that feed concentration and loading of the reactors should not exceed 20 Kg per cubic meter per day limits.
Changing the mean residence time from 8 to 24 hours showed a remarkable effect on the behavior of the reactors. Stability of the systems was more evident at MRT’s of more than 12 hours.
The study provided a very good basis for comparing the effect of packing in removal efficiency of the system. The reactor filled with standard pall rings made of polypropylene with an effective surface area of 180 m2/m3 performed much superior to reactors filled with PVC packing with surface area of 150 m2/m3 and reactor filled with polyethylene rings of 53 m2/m3. It was also noticed that under low rates of loading, all reactors can produce acceptable results, therefore indicating that packing characteristics are important under higher loading.
Finally it was concluded that UABF system is ideal for treatment of strong wastes, such as sugar production effluents, capable of removal efficiencies up to 85 percent under organic loading of 20 kg COD per cubic meter per day. Although conventional commercial packing could produce higher results, but normal cheap packing can also be used. Therefore this technique provides a powerful tool for controlling strong industrial wastewater.
( M. Farzadkia, Ph.D., M. Shariat, Ph.D., A. Mesdaghinia, Ph.D., S. Nasseri, Ph.D., A. Mahvi, Ph.D. )
1- Tehran University of Medical Sciences, Dept. of Environmental Health Engineering
Keywords : Sludge , Composting , Tehran sewage Abstract :
Anaerobic digestion process is a classical method of sludge stabilization in most wastewater treatment plants in western countries according to their regional conditions. This method is used in Iran for the southern Tehran wastewater treatment plant, which employs activated sludge process.
Anaerobic digestion method utilizes about 40 to 50 percent of capital and annual costs in addition to operation problems, therefore most designers interest to suggest more appropriate options.
Composting of sewage sludge using aerated static piles is a simple and cheap method for sludge stabilization in Europe and United States. According to the hydroclimatological and land conditions, this method may effectively be used in Iran. The main purpose of this study was to determine the feasibility of sewage sludge stabilization by aerated static piles composting designed for Tehran Southern Sewage Treatment Plant.
This research has been completed in four steps through a bench scale system. The results of this research demonstrated that this process has significant ability of sludge stabilization, if the piles are provided by mixing of sludge, sawdust and woodchips with the volume ratio of 1:1.8 and providing depth and adequate cover.
Microbial quality of resulted compost was evaluated as the class A and PFRP (processes to further reduce pathogens) criteria of USEPA standards for agricultural uses.
Initial estimate of capital and annual costs for a 25 years project consisting of composting and anaerobic digestion units indicated that the present value of composting method is less than half of the present value of anaerobic digestion method for the Southern Tehran Sewage Treatment Plant, showing the long-term economic feasibility of this agotenn.
( 1P. Nassiri, Ph.D., 2M. Abbaspour, Ph.D., 3S. Taefi Aghdam, M.S. )
1- Tehran University of Medical Sciences, Dept. of Occupational Health 2- Sharif University of Technology 3- Islamic Azad University
Keywords : Power plant , Process , Noise pollution , Frequency analysis Abstract :
Noise is one of the major environmental pollutants in the power plants.
This desciptive, cross sectional study has been carried out at the 1320 MW power plant situated in the province of Tehran. The acoustic environment was described by sound pressure level. Speech interference level (SIL) values for workers in different sections were also determined.
Moreover isosonic contours were drawn in open area of the power plant where the F.D. fans gas section were located. The results indicated that the SPL generally amounted to levels higher than 85 dbA, the permissible recommended level for 8 hours exposure.
Spectral analysis of the noise indicated that high SPL exceeded the permissible level in some octave-band frequencies in some parts with regard to the determined SIL values which were more than the maximum vocal effort ; communication between workers and /or supervisors were appraised to be very difficult or impossible.
One of the major reasons of excessive noise is due to the structure-born noise and reflection from adjacent equipments and boundries.
Study of environmental radioactivity in the air, soil and agricultural products is very important for their biological effects and public health views.
In this study 65 samples of soil, wheat and rice from Isfahan’s farms were collected. After preparing the samples, alpha and gamma radioactivity were measured. Spectrometry technique was used for qualitative determination of all the radioelements found in the samples. For gamma spectrometry, Na-I and Ge-Li , and for alpha counting Silicon surface barrier detector were used.
The results showed that not only the natural radioelements, but artificial raidonuclides, such as Cs-137 which is one of the nuclear fallout products; were found in the samples.
The results showed that the mean concentration activity in the soil, wheat and rice were 772.3, 124.6 and 55.05 Bq/kg , respectively. This showed that, the radioactivity in the soil samples were about 14 times higher than rice and 6 times higher than wheat samples.
( M. Soltanian, Ph.D., A. Mesdaghinia, Ph.D., S. Nasseri, Ph.D., F. Vaezi, Ph.D. )
Tehran University of Medical Sciences, Dept. of Environmental Health Engineering
This study was conducted for determination of Upflow Anaerobic Sludge Blanket(UASB) reactor performance in treatment of petroleum wastewater.
The reactor volume was 100 liters. For initial start-up, reactor was seeded by a cultured seed that was taken from anaerobic lagoons of industrial slaughter-house of Kermanshah and Gharasu River muds in downstreams of Kermanshah refinery. A mixture of petroleum wastewater and mollasses was used as substrate during reactor start-up. Concentration of mollasses was 2500 mg/l as COD in each liter of reactor feed.
The start-up was followed by maintaning reactor temperature and HRT in 35° C and 24 hours respectively.
Granulation was completed after 117 days and reactor removed 89.76 percent of TCOD influent. The height of reactor did not affect in wastewater treatment. The COD removal efficiency of reactor in HRT of 24 hours for petroleum wastewater treatment was more than 90 percent.
For hydraulic retention time of 18,12 and 9 hours, COD removal efficiency was 86.99, 84.92 and 82.11 percent, respectively. During reactor operating in HRT of 6 hours, reactor encountered sludge washout and was unstable. After 35 days of operation in this condition, COD removal efficiency falled to 60 percent.
The results showed that optimum HRT for treatment of petroleum wastewater by the UASB reactor is 9 hours.
( 1Gh. Omrani, Ph.D., 2P. Mahasti, M.S. )
1- Tehran University of Medical Sciences, Dept. of Environmental Health Engineering 2- Islamic Azad University
According to UNEP guidelines, the best method for hazardous waste classification is through qualitative and quantitative approach.
In this study a list of 125 hazardous waste substances identified by UNEP, EEC and Canada were observed and compared according to their origins, characteristics and disposal methods in Iran. Results showed that pesticides are the most dangerous substances, in term of their toxicity.
In 60.71% of these waste materials, besides toxicity, some other effects of hazardous materials were recognized. Chemicals and petrochemicals wastes with 82.14% and 43.57% , respectively, showed the highest production rates and food industries with 5.35% hazardous wastes production had the minimum importance. Also 95.75% of these substances were considered as recycleable.
Results confirmed that 46% of dangerous and toxicant wastes should be firstly treated and then disposed with extra caution through sanitary land fill methods. About 39.28% of these materials should be disposed by using special incinerators.
( M. Tabibian, Ph.D. )
Tehran University , Faculty of Environment
Keywords : Planning , Land , Spatial planning , Regulations , Structure of organisation Abstract :
The consideration of spatial planning, and the creation of a relevant branch within the Plan and Budget Organization of Iran, took place at a time when there was not real commitment to this kind of planning, either in academic circles, or among the managers of the Organization.
Because of years of enforcement of sectorial planning, the idea of spatial planning, as a new approach to planning, was not welcomed by the responsible authorities; hence, this approach has never played a relevant role in the decision making process of the macro socio-economic and development strategies of the country.
Spatial planning in Iran began in 1974. The primary aim of the spatial plans was targeted towards the resolution of issues that needed urgent solution. These included: population growth; rapid expansion of cities; gradual disappearance of traditional activities; excessive use of resources beyond their capacity, and the abandonment of area with high potentials.
Planing, management, and use of the environment is a dynamic process, and its effects are to be perceived and evaluated through time. Although spatial planning is still at its early stages in Iran, the existance of significant natural potentials and opportunities,and the richness of the environment encourage us, more than ever, to prepare a spatial plan for the environment.
The preparation of a plan, based on objectives that would allow the rational use of resources and the protection of the environment, depends upon a thorough revision of the development strategy. decisions, and regulations of the past, together with a proper evaluation of the impact of policies already implemented. Further, it would require: accurate definitions of planning policies in general, and of spatial planning in particular; the coordination between different sectors; and, finally, a proper definition of the objectives regarding spatial planning.
Under these conditions, the extension of spatial planning to all government`s areas and levels in the country would be possible through the revision and correction of each section within the planning system.
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