Performance of activated sludge diffusion for biological treatment of hydrogen sulphide gas emissions

2013 ◽  
Vol 68 (9) ◽  
pp. 1932-1939 ◽  
Author(s):  
Vera L. Barbosa ◽  
Richard M. Stuetz
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Hydrogen Sulphide ◽  
Biological Treatment ◽  
Suspended Solids ◽  
Wastewater Treatment Plants ◽  
Broad Application ◽  
H2s Removal ◽  
Treatment Performance ◽  
Solids Concentration

Odours from wastewater treatment plants are comprised of a mixture of various gases with hydrogen sulphide (H2S) often being the dominant constituent. Activated sludge diffusion (ASD) as a biotreatment system for odour abatement has been conducted for over 30 years but has limited broad application due to disagreement in the literature regarding the effect that ASD may have on wastewater treatment performance. The effects of continuous H2S diffusion at 25 ppmv, with weekly peaks of approximately 100 ppmv, on H2S removal efficiency and wastewater treatment performance was evaluated over a 2-month period using an activated sludge pilot plant. H2S removal averaged 100% during diffusion at 25 ppmv, and 98.9% during the 100 ppmv peak periods. A significant increase in mixed liquor volatile suspended solids concentration (P < 0.01) was observed during H2S diffusion, which may be due to an increase in H2S-degrading microorganisms. There was no adverse effect of H2S on nitrification throughout the ASD trials. Ammonia (NH3) removal was slightly better in the test receiving H2S diffusion (87.6%) than in the control (85.4%). H2S diffusion appeared to improve robustness of the AS biomass to operational upsets.

Relationship for Clarification Efficiency of Circular Secondary Clarifiers

1992 ◽  
Vol 26 (9-11) ◽  
pp. 2539-2542 ◽  
Author(s):  
N. S. Voutchkov
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Suspended Solids ◽  
Wastewater Treatment Plants ◽  
Full Scale ◽  
Solids Concentration

This paper discusses a regression-based model describing clarification efficiency of circular activated sludge secondary clarifiers. Surface overflow rate was found to be well correlated with effluent suspended solids, sidewater depth and settled sludge volume at three full scale wastewater treatment plants during a six month study. Relationship was verified to be sufficiently accurate for prediction of effluent suspended solids concentration over a six month period at another three treatment plants.

Evaluating the treatment performance of a full scale Activated Sludge Plant in Islamabad, Pakistan

2012 ◽  
Vol 7 (1) ◽  
Author(s):  
S. S. Fatima ◽  
S. Jamal Khan
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plant ◽  
Suspended Solids ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Full Scale ◽  
Operational Parameter ◽  
Mixed Liquor ◽  
Treatment Performance

In this study, the performance of wastewater treatment plant located at sector I-9 Islamabad, Pakistan, was evaluated. This full scale domestic wastewater treatment plant is based on conventional activated sludge process. The parameters which were monitored regularly included total suspended solids (TSS), mixed liquor suspended solids (MLSS), mixed liquor volatile suspended solids (MLVSS), biological oxygen demand (BOD), and chemical oxygen demand (COD). It was found that the biological degradation efficiency of the plant was below the desired levels in terms of COD and BOD. Also the plant operators were not maintaining consistent sludge retention time (SRT). Abrupt discharge of MLSS through the Surplus Activated sludge (SAS) pump was the main reason for the low MLSS in the aeration tank and consequently low treatment performance. In this study the SRT was optimized based on desired MLSS concentration between 3,000–3,500 mg/L and required performance in terms of BOD, COD and TSS. This study revealed that SRT is a very important operational parameter and its knowledge and correct implementation by the plant operators should be mandatory.

Increased performance of secondary clarifiers using dynamic distribution of minimum return sludge rates

2009 ◽  
Vol 60 (9) ◽  
pp. 2439-2445 ◽  
Author(s):  
A. Lynggaard-Jensen ◽  
P. Andreasen ◽  
F. Husum ◽  
M. Nygaard ◽  
J. Kaltoft ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Suspended Solids ◽  
Considerable Increase ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Total Flow ◽  
Equal Distribution ◽  
Solids Concentration ◽  
Hydraulic Load ◽  
And Control

Most wastewater treatment plants have several secondary clarifiers or even more sets of clarifiers including several secondary clarifiers, and in practice it is a well known problem that equal distribution of the load to the single clarifier (or set of clarifiers) is very difficult—not to say impossible—to obtain. If the problem is neglected, quite a big percentage of the total clarifier capacity—measured as the max. allowed hydraulic load—can be lost. Further, return sludge rates are seldom controlled by any other means than as a (typically too high) percentage of the inlet to the wastewater treatment plant—giving a varying and too low suspended solids concentration in the return sludge, which again can lead to an unnecessary use of polymer in the pre-dewatering of the surplus sludge taken from the return sludge. A control of the return sludge rate divided into two parts - control of the total return sludge flow and control of how the total flow shall be distributed between the secondary clarifiers - is able to solve the mentioned problems. Finally, as shall be demonstrated on full scale wastewater treatment plants, a considerable increase of the hydraulic capacity of the treatment plants can be obtained.

scholarly journals Reliability of removal of selected pollutants in different technological solutions of household wastewater treatment plants

2017 ◽  
Vol 35 (1) ◽  
pp. 141-148 ◽  
Author(s):  
Michał Marzec
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Suspended Solids ◽  
Wastewater Treatment Plants ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Total Suspended Solids ◽  
Hybrid Reactor ◽  
Limit Values

AbstractThe reliability of removal of selected contaminants in three technological solutions of the household sewage treatment plants was analysed in this paper. The reliability of the sewage treatment plant with activated sludge, sprinkled biological deposit and hybrid reactor (activated sludge and immersed trickling filter) was analyzed. The analysis was performed using the Weibull method for basic indicators of impurities, BOD5, COD and total suspended solids. The technological reliability of the active sludge treatment plant was 70% for BOD5, 87% for COD and 66% for total suspended solids. In the sewage treatment plant with a biological deposit, the reliability values determined were: 30% (BOD5), 60% (COD) and 67% (total suspended solids). In a treatment plant with a hybrid reactor, 30% of the BOD5and COD limit values were exceeded, while 30% of the total suspended solids were exceeded. The reliability levels are significantly lower than the acceptable levels proposed in the literature, which means that the wastewater discharged from the analysed wastewater treatment plants often exceeds the limit values of indicators specified in currently valid in Poland Regulation of the Minister of Environment for object to 2000 population equivalent.

Tracking influent inorganic suspended solids through wastewater treatment plants

2006 ◽  
Vol 54 (8) ◽  
pp. 101-109 ◽  
Author(s):  
G.A. Ekama ◽  
M.C. Wentzel ◽  
S.W. Sötemann
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Suspended Solids ◽  
Wastewater Treatment Plants ◽  
Settling Tank ◽  
Treatment Plant ◽  
Primary Sludge ◽  
Unit Operations ◽  
Sludge Digestion ◽  
N Removal

From an experimental and theoretical investigation of the continuity of influent inorganic suspended solids (ISS) along the links connecting the primary settling tank (PST), fully aerobic or N removal activated sludge (AS) and anaerobic and aerobic sludge digestion unit operations, it was found that the influent wastewater (fixed) ISS concentration is conserved through primary sludge anaerobic digestion, activated sludge and aerobic digestion unit operations. However, the measured ISS flux at different stages through a series of wastewater treatment plant (WWTP) unit operations is not equal to the influent ISS flux, because the ordinary heterotrophic organisms (OHO) biomass contributes to the ISS flux by differing amounts depending on the active fraction of the VSS solids at that stage.

scholarly journals The present situation and trends of wastewater treatment in small settlements and rural areas of Lithuania

2019 ◽  
pp. 243-250
Author(s):  
Regimantas Dauknys
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Surface Waters ◽  
Rural Areas ◽  
Biological Treatment ◽  
Wastewater Treatment Plants ◽  
Present Situation ◽  
Treatment Facilities ◽  
Biological Filters ◽  
Activated Sludge Systems

This article presents the wastewater treatment in small settlements and rural areas ofLithuania, including descriptions of capacity and loading of wastewater treatment plants(WWTPs), types of treatment facilities, and development trends of biological treatmentfacilities. In 2000 Lithuania had 597 WWTPs with capacity up to 1000 m3/d, 95% of them arethe biological treatment plants. Today the most of these WWTPs are unloaded due to thetendency to centralise wastewater treatment in rural areas of Lithuania that were in the eightand ninth decades.In small settlements and rural areas of Lithuania the aeration facilities are predominant. In theeight and ninth decades practically only the activated sludge systems were built. The situationbegan to change in the last decade of the last century: the biological filters and soil filtrationfacilities with discharge into surface waters were applied more frequently, so the building ofaeration facilities started to decrease.

Operational and control practices to improve the performance of small wastewater treatment plants in Catalonia

2000 ◽  
Vol 41 (1) ◽  
pp. 53-56 ◽  
Author(s):  
C. Camos ◽  
S. Martorell ◽  
A. Rey ◽  
D. Güell ◽  
J. Robusté ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Suspended Solids ◽  
Wastewater Treatment Plants ◽  
Solids Separation ◽  
And Control ◽  
Separation Problems

Observations during routine wastewater treatment plants (WWTP) controls in Catalonia suggest that in small Activated Sludge (AS) plants suspended solids separation problems could reach a special intensity. In order to evaluate their incidence, filamentous scums, clarifier floating solids, rising sludge, deflocculation and bulking incidences occurring in 34 small WWTP were controlled for a year. To improve the efficiency of these plants, analyses of mainly suspended solids separation problems were systematically performed.

Ten Years Experience with a Highly Loaded Activated Sludge Plant

1984 ◽  
Vol 16 (12) ◽  
pp. 649-660
Author(s):  
P Balmér ◽  
S Hallquist ◽  
M Hernebring
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Residence Time ◽  
Suspended Solids ◽  
Treatment Plant ◽  
Volume Index ◽  
Sludge Volume Index ◽  
Solids Concentration ◽  
Cell Residence Time ◽  
Highly Loaded

The Rya wastewater treatment plant in Gothenburg, Sweden serves 640 000 population equivalents. It is an extremely highly loaded activated sludge plant without presetting with a mean cell residence time of about 0.5 days. Ten years experience proves that the plant is capable of removing about 70% of the BOD load. The effluent BOD is mainly caused by non settleable suspended solids due to the partly dispersed growth of the activated sludge. The low mean cell residence time and the high suspended solids concentration in the aeration basin influent gives an activated sludge with low viability and in mass balance studies it was determined that only 12% of the influent COD and about 40% of the BOD was oxidized by the activated sludge. The activated sludge has consistently had a very low sludge volume index and the settling basins could thus be very highly loaded. The surplus activated sludge could be thickened to solids concentrations over 6%. After dewatering the sludge was either lime treated or co-composted with bark. The plant is manned only eight hours five days a week. During unmanned time there are standby personnel. Data is presented on man power, energy and chemical use, and on costs.

Occurrence and reduction of pharmaceuticals in the water phase at Swedish wastewater treatment plants

2012 ◽  
Vol 66 (4) ◽  
pp. 783-791 ◽  
Author(s):  
P. Falås ◽  
H. R. Andersen ◽  
A. Ledin ◽  
J. la Cour Jansen
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Nitrogen Removal ◽  
Biological Treatment ◽  
Wastewater Treatment Plants ◽  
Trickling Filter ◽  
Screening Programs ◽  
Research Institutes ◽  
Influent Water ◽  
Human Usage

During the last decade, several screening programs for pharmaceuticals at Swedish wastewater treatment plants (WWTPs) have been conducted by research institutes, county councils, and wastewater treatment companies. In this study, influent and effluent concentrations compiled from these screening programs were used to assess the occurrence and reduction of non-antibiotic pharmaceuticals for human usage. The study is limited to full-scale WWTPs with biological treatment. Based on the data compiled, a total of 70 non-antibiotic pharmaceuticals have been detected, at concentrations ranging from a few ng/L to several μg/L, in the influent water. The influent concentrations were compared with the sale volumes and for many pharmaceuticals it was shown that only a small fraction of the amount sold reaches WWTPs as dissolved parent compounds. Pharmaceuticals with low reduction degrees at traditional WWTPs were identified. Further comparison based on the biological treatment showed lower reduction degrees for several pharmaceuticals in trickling filter plants compared with activated sludge plants with nitrogen removal.

Real time control of a combined UASB-activated sludge wastewater treatment configuration

2002 ◽  
Vol 45 (4-5) ◽  
pp. 279-287
Author(s):  
C.M. Polito-Braga ◽  
M. von Sperling ◽  
A.R. Braga ◽  
R.T. Pena
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Real Time ◽  
Control Strategy ◽  
Suspended Solids ◽  
Biomass Concentration ◽  
Upflow Anaerobic Sludge Blanket ◽  
Anaerobic Sludge ◽  
Successful Implementation ◽  
Solids Concentration

This paper presents a combined wastewater treatment configuration composed by an Upflow Anaerobic Sludge Blanket (UASB) reactor followed by an Activated Sludge (AS) system. A control strategy has been developed for this innovative (especially for domestic sewage) treatment configuration and tested in a real pilot-scale system called STEPAA – Wastewater Treatment System by Anaerobic and Aerobic Processes. The proposed UASB–AS control strategy, including fault detection and recovery, and its successful implementation in real time is presented. This novel control strategy was developed to keep the final effluent suspended solids concentration in the range specified by the State environmental agency, in spite of incoming load disturbances. The control strategy is based on two cascaded PI (Proportional + Integral) controllers, which manipulates the recycling rate into the AS-reactor to control the effluent suspended solids concentration. A 2-dimensional nonlinear mapping (an empirical look-up table), which gives the sludge waste rate as a function of the influent flowrate and AS-reactor biomass concentration, is used to keep the AS-reactor biomass concentration in a range that guarantees a good substrate removal without inconveniences to the AS-settler operation (and consequently to the solids removal). Experimental results are provided to demonstrate the system performance.

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