scholarly journals Tolerable Risk for Hydrogen Sulfide in Sewage Treatment Plant- STP

Author(s):  
Mohieldeen M. A. Ahmed ◽  
Mohammed H. M. Gaily ◽  
Khalid M.O. Ortashi ◽  
Omer M.A. Al Ghabshawi ◽  
Nagwa F. Bashir ◽  
...  

Hydrogen sulphide is a toxic gas, it can cause a range of physiological responses from simple annoyance to permanent injury and death. There are a number of approaches to deal with the impacts of toxic gases. This study focused on minimizing the hazard exposure for hydrogen sulfide in the different operational zones for activated sludge process in sewage waterplant. Research tools/ approaches conducted were interviews, toxic gas testers, analysis report interpretation &amp; quantitative risk assessment method. The study was conducted on Arabian Peninsula during the period (September 2019- September 2021). The (13) operational locations tested for toxic gas concentrations were inlet chamber, outlet channel, coarse /fine screens, primary sedimentation tank, activated sludge tanks, secondary sedimentation tanks, gas desulfurization unit, disc filters, chlorine dosing unit, sludge dewatering, sludge silos and digester tanks. The study found that the highest concentration for H<sub>2</sub>S in the inlet chamber/ outlet channel. The severity hazards in the sewage treatment plant using activated sludge process are the asphyxiation by H<sub>2</sub>S was extremely high can cause harm to public health, followed by the radiation hazard followed by electrical hazard, then (working at height, mechanical, traffic, health, chemical, physical, ergonomic, environmental, microbial and natural). The frequency of hazards occurrence is asphyxiation by H<sub>2</sub>S was extremely high followed by the radiation hazard and health hazard including the infection with Covid 19 virus followed by mechanical hazard then (electrical, traffic, ergonomic, natural, chemical, physical and natural). Control measures were recommended to minimize the risk of asphyxiation by H<sub>2</sub>S in the working environment at the STP.

1988 ◽  
Vol 20 (4-5) ◽  
pp. 143-152 ◽  
Author(s):  
M. Tendaj-Xavier ◽  
J. Hultgren

Bromma sewage treatment plant is the second largest plant in Stockholm with a design flow of 160,000 m3/d. The wastewater is treated mechanically, chemically by pre-precipitation with ferrous sulphate, and biologically by the activated sludge process. The requirements for the plant are 8 mg BOD7/l, 0.4 mg P/l and 2 mg NH4+-N/l. The requirement for ammonia refers to the period July-October. In order to meet those rather stringent requirements, the biological step was expanded 3 years ago with 6 new sedimentation tanks. The 6 new tanks have the same area as the 6 old ones but they have only a depth of 3.7 m compared with the depth of the old tanks, 5.7 m. Experience from the first years of operation of the new tanks is that these tanks are more sensitive and less efficient than the older ones. It seems that the effluent suspended solids concentration from the old tanks is less influenced by rapid flow variations than the concentration in the effluent from the new secondary sedimentation tanks. During the nitrification period denitrification takes place to some degree in the secondary sedimentation tanks. This may cause loss of solids and it has been observed that the deeper old tanks usually produce an effluent of better quality and seem to be less influenced by denitrification than the new ones.


1991 ◽  
Vol 23 (4-6) ◽  
pp. 907-916 ◽  
Author(s):  
M. Terashi ◽  
S. Hamada

In the activated sludge process, the cause of filamentous bulking is often the filamentous bacteria Type 021N. At the Kitaminato sewage treatment plant, it was found that when the DO in the aeration tank decreased, filamentous bulking occurred. If the low DO condition is allowed to continue, anaerobic degraded organic matter is produced which creates a favorable condition for the multiplication of Type 021N. Entosiphon sp. is reported to show resistance to low DO; however, sometimes before filamentous bulking occurs, Entosiphon sp. itself multiples. Also if Entosiphon sp. increases and Cinetochilummargaritaceum, of the Ciliophora, multiples, then bulking by Type 021N has been seen not to occur. Cinetochilummargaritaceum has low resistance to hydrogen sulfide; therefore, hydrogen sulfide must not be present in the aeration tank and this means that bulking by Type 021N can not become serious. However, if filamentous bulking becomes serious, only increasing the DO level in the aeration tank will not cause the disappearance of the filamentous bulking. At this stage, if we allow 30% of the final effluent to flow back into the grit chamber, then Type 021N decreases. This is because Trithigmostomacucullulus, of the Ciliophora, increases to 3,000 number/ml, and it ingests Type 021N.


2017 ◽  
Vol 1 ◽  
pp. 1
Author(s):  
Zhan Yang

Activated sludge process is the most widely used technology in sewage bioremediation up to now. However, there is also a serious problem with this technology, that is, a great amount of sludge will be left over. In view of this situation, a study has been carried out through the domestic activated technology for sludge treatment and also research on the effective sludge treatment. They made use of the microbial decomposition to decompose the oxide by using the means of physical, chemical, biological, etc. to minimize the effluent from the sewage treatment plant and thus, reduced the amount of sludge produced.


2009 ◽  
Vol 4 (2) ◽  
Author(s):  
S. M. Faheem ◽  
M. A. Khan

A study was conducted on filamentous bacteria implicated in bulking and foaming problems in activated sludge process of sewage treatment plant in Dubai, United Arab Emirates over a period of six months. To determine morphological characteristics of diverse filaments, foam and mixed liquor samples were collected and studied using various simple and differential staining techniques. Fluorescent in situ hybridization analysis was carried out in mixed liquor samples with nocardioform group specific probes using VIT kit (Vermicon Identification Technology, Vermicon, Munich). The dominant filamentous bacteria identified from mixed liquor and foam samples included: A long branched form of Gram varibale nocardioform actinomycetes species, Thiothrix, Eikelboom Type 021N, Sphaerotilus natans, Beggiatoa and Nostocoida limicola type I. Occasionally attached growth forms of Eikelboom type 0041/0675 like filaments were observed in mixed liquor and foam samples especially during warm weather. All filamentous bacteria identified were found in both the samples throughout the study period. FISH analysis successfully identified filamentous and non-filamentous morphotypes of nocardioform group members. It is concluded that specific filamentous bacterial population in mixed liquor and foaming activated sludge was constant and not dependent on variable wastewater characteristics.


2017 ◽  
Vol 1 (1) ◽  
pp. 1
Author(s):  
Zhan Yang

Activated sludge process is the most widely used technology in sewage bioremediation up to now. However, there is also a serious problem with this technology, that is, a great amount of sludge will be left over. In view of this situation, a study has been carried out through the domestic activated technology for sludge treatment and also research on the effective sludge treatment. They made use of the microbial decomposition to decompose the oxide by using the means of physical, chemical, biological, etc. to minimize the effluent from the sewage treatment plant and thus, reduced the amount of sludge produced.


1993 ◽  
Vol 28 (11-12) ◽  
pp. 231-237
Author(s):  
M. Ichikawa ◽  
K. Simizu ◽  
K. Iwahori

A diagnosis expert system for the activated sludge process was developed in conformity to our experience and reported studies. Using the biota observed by microscopic and data measurement easily obtained, i.e. pH or DO etc., the process treatability or the activated sludge condition was diagnosed and evaluated by this system. In this paper, the effectiveness of the diagnosis expert system was investigated using the microscopic and measurement results from both the actual sewage treatment plant and the bench-scale experiment. As a result, the low loading and the progress of nitrification were presumed in the case of the actual plant and the variations of treatment condition depending on DO set values were evaluated satisfactorily in the case of the bench-scale experiment. Therefore, it was shown that this system was applicable to the diagnosis of the activated sludge process.


1990 ◽  
Vol 22 (7-8) ◽  
pp. 123-129 ◽  
Author(s):  
Jörg Londong ◽  
Stefan Zander

Sewage from 700,000 PE, roughly half of which is discharged by industry, is treated at the Buchenhofen plant operated by the WWMA, using a conventional, activated-sludge process without specific nutrient elimination. A draft management plan has been prepared for the receiving stream of the treatment plant, the Lower Wupper. The chief forms of use for the waters are fixed in binding agreements. The use entailing the strictest limiting values is recreational fishing, which demands surface water quality class II. Very substantial demands, which must be regarded as at least equivalent to state-of-the-art technology, are imposed on the Buchenhofen facility. The Institut für Siedlungswasserbau, Wassergütewirtschaft und Abfalltechnik at the University of Stuttgart was commissioned to formulate realistic purification objectives for the treatment plant and to prepare expansion concepts. At Buchenhofen, the single-stage activated sludge process with nitrification and preliminary de-nitrification has proved to be the most effective method for eliminating nitrogen while simultaneous precipitation followed by flocculation-filtration is the best process for eliminating phosphorus. For purely scientific reasons, however, the extreme demands in terms of ammonium and nitrite rule out expansion of a treatment plant of this size. The proposed designs therefore require validation through commercial-scale testing. Only after a 6- to 12-month test series has been evaluated will a draft design be prepared for approval, ultimately enabling the plant to be expanded and to fulfil the management planning objective of achieving surface water quality class II in the Wupper.


2016 ◽  
Vol 78 (7-4) ◽  
Author(s):  
Norul Ashikin Norzain ◽  
Shafishuhaza Sahlan ◽  
Fatah Ab Halim ◽  
Norhaliza Abdul Wahab

Activated sludge process is an important stage in Wastewater Treatment Plant (WWTP). In this study, model of the activated sludge process from Bunus Regional Sewage Treatment Plant Kuala Lumpur, Malaysia is developed. This paper focuses on modelling and model reduction of the WWTP system. The model with best fits of higher than 80% and the order of less than 10 is selected. For modelling purposes, data obtained is stimulated and modelled using System Identification technique which employ linear model ARX. For model reduction purposes, the high order model is reduced using model order reduction (MOR) of a combination of Singular Perturbation Approximation (SPA) and Frequency Domain Gramian based Model Reduction (FDIG) method. From the modelling results obtained, the ARX model with best fit of 85.11% is selected. Meanwhile, for the MOR FD-SPA technique, a 9th order model is selected with  reduction error between frequencies 0.05 rad/s and 1.4 rad/s.


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