Nitrogen Reduction – Volume Demand

1992 ◽  
Vol 25 (4-5) ◽  
pp. 233-240
Author(s):  
T. Palmgren
Keyword(s):  
Suspended Solids ◽  
Age Factors ◽  
Reduction Rate ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Aeration Tank ◽  
Nitrogen Reduction ◽  
Solids Concentration ◽  
Yearly Average ◽  
Nitrification Process

Due to the slow growth of nitrification bacteria at low temperatures, nitrogen reduction normally requires long hydraulic retention time during winter. Important for the nitrification process is the aerated sludge age. Factors influencing the sludge age are aerated volume, mixed liquor suspended solids concentration, organic loading and sludge yield. In an existing plant you cannot easily expand the volume and the load is difficult to decrease. But the suspended solids concentration can be increased by running the biological step with the contact stabilisation process. At the Käppala Association sewage treatment plant in Lidingö just outside Stockholm, one of the six aeration tanks has been reconstructed for full scale nitrogen removal experiments. In this tank the old aeration system has been replaced with rubber membrane diffusers. Further more there are several zones separated by walls in the tank. The tank can thereby be run with great flexibility. By running it with the contact stabilisation process, the sludge age has been improved by a factor between 1.5 and 2 and thereby it succeeds in keeping the nitrification bacteria in the system even during snow melting. At temperatures of about 9 °C and hydraulic retention times of less than 3 hours in the contact zone there has been a nitrification degree of up to 50 to 60 %. The experiment was conducted with a stabilisation zone of up to half the total volume of the aeration tank. The main purpose for the experiments during the winter seasons was to improve nitrification. Keeping the nitrifiers in the system had been a crucial problem during previous years. When the nitrifiers were lost with an increased flow and decreased temperature the nitrification process didn't restart until the temperature was increased and the load decreased. Usually this didn't occur until the middle of the summer meaning a loss of nitrification for up to six months. In Sweden there is a goal set for 50 % nitrogen reduction for the plants in the Stockholm region. At Käppala we manage to keep 60 to 70 % nitrogen reduction during the warm season, that is from July to December. If we can keep up the nitrification the whole year we can achieve 50 % as a yearly average under normal conditions even though we can't keep the nitrogen reduction rate as high during the cold season.

The Infuence of the Depth of the Secondary Sedimentation Tanks on the Sedimentation Efficiency at Bromma Sewage Treatment Plant

1988 ◽  
Vol 20 (4-5) ◽  
pp. 143-152 ◽  
Author(s):  
M. Tendaj-Xavier ◽  
J. Hultgren
Keyword(s):  
Activated Sludge ◽  
Suspended Solids ◽  
Ferrous Sulphate ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Design Flow ◽  
Activated Sludge Process ◽  
Solids Concentration ◽  
Rapid Flow

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.

The use of dynamic BNR and two-dimensional clarifier modelling to investigate nitrogen removal at Eastern Treatment Plant, Melbourne, Australia

1999 ◽  
Vol 39 (6) ◽  
pp. 89-96
Author(s):  
J. R. Messenger ◽  
J. C. Smith ◽  
M. J. Tetreault ◽  
C. Vitasovic ◽  
S. Zhou ◽  
...  
Keyword(s):  
Transfer Rate ◽  
Suspended Solids ◽  
Oxygen Transfer Rate ◽  
Treatment Plant ◽  
Aeration Tank ◽  
Two Dimensional ◽  
Solids Loading ◽  
Solids Concentration ◽  
The Impact ◽  
Denitrification Process

The use of process and two-dimensional clarifier modelling to investigate the implications of upgrading Melbourne Water's Eastern Treatment Plant to a nitrification/denitrification process is discussed. Results indicate that the existing clarification capacity is sufficient for the increased solids loading arising from operation at a nitrifying sludge age but that the existing diffuser system may need to be replaced in order to achieve the required oxygen transfer rate. The impact of step feeding into unaerated zones to reduce the aeration tank suspended solids concentration and to achieve denitrification is discussed and the installation of baffles to improve the performance of peripheral feed clarifiers is suggested.

Isolation and Identification of Nitrobacteria Adapted to Low Temperature

2012 ◽  
Vol 518-523 ◽  
pp. 406-410 ◽  
Author(s):  
Yun Hao ◽  
Xiu Guang Jiang ◽  
Qing Tian ◽  
Ai Yin Chen ◽  
Bao Ling Ma
Keyword(s):  
Low Temperature ◽  
Removal Efficiency ◽  
Nitrate Removal ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Ammonia Nitrogen ◽  
Aeration Tank ◽  
Isolation And Identification ◽  
Nitrification Process

In this study, a scientific method which can be used to improve nitrification process at low temperature in the sewage treatment plant was introduced. The activated sludge samples were taken from aeration tank of the sewage treatment plant when the outside temperature was below 0°C (water temperature below 12 °C). Five kinds of nitrobacteria strains with cold-resistance and higher activity of ammonia degradation were isolated from aeration tanks. The physiological properties showed the five strains were identified into Sphingobacteriaceae、Rhodanobacter sp.、Pseudomonas sp.、Pandoraea sp. and Perlucidibaca piscinae. All of the strains could convert ammonia-nitrogen or NO2- into NO3- in the medium at 10°C. The ammonia and nitrate removal efficiency could be reached 80.9% and 80.3% respectively. Comparing to the unvaccinated one, the removal efficiency can be increased by 50%, which proved the isolated nitrobacteria could be applied to biological nitrification process of sewage treatment at low-temperature.

Low Cost Packaged Sewage Treatment Plant for Production of High Quality Effluent at Small Works

1993 ◽  
Vol 27 (5-6) ◽  
pp. 405-412 ◽  
Author(s):  
B. Chambers ◽  
J. Whitaker ◽  
A. F. Elvidge
Keyword(s):  
Suspended Solids ◽  
Low Cost ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Ammonia Nitrogen ◽  
Aeration Tank ◽  
Effluent Quality ◽  
Demonstration Plant ◽  
The Uk

In the UK there are over 7000 small works which treat the sewage from populations of less than 10,000. Many of these works are at risk of non-compliance with effluent quality consents and options for improving the standard of treatment are being pursued by many utilities. WRc and Anglian Water Services have developed designs for packaged sewage treatment plants to serve populations in the range of 1000-10,000. A demonstration plant has been constructed at the Waterbeach STW of Anglian Water to serve a population of about 6,500. Target effluent quality is 15:20:5mg/l of BOD, SS and ammonia nitrogen respectively on a 95 percentile basis. Following plant commissioning a process performance evaluation programme was commenced in February 1991. Nitrification was established after about 6 weeks of operation but suspended solids values have been affected by the presence of a stable foam on the surface of the aeration tank. Process modifications have reduced the effect of this phenomenon substantially and effluent quality has improved.

A seven year plan for upgrading the 200.000 p.e. treatment plant of Uppsala, Sweden

1994 ◽  
Vol 29 (12) ◽  
pp. 117-127
Author(s):  
Jan Erik Lind ◽  
Ernst Olof Swedling
Keyword(s):  
Cost Efficiency ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Working Environment ◽  
Regional Environment ◽  
Nitrogen Reduction ◽  
Total Investment ◽  
Close Cooperation ◽  
The Cost

The sewage treatment plant of Uppsala was originally built in 1946 and has since then been extended and upgraded several times up to 1972 when the last major upgrading was completed. In 1987 it was decided to renew the treatment plant for at least another 20-30 years of operation and to upgrade the biological process to include nitrogen reduction. A 7 year plan covering some 18 items with a total investment cost of approximately 120 MSEK was set in action during 1987. The aim was to raise the cost efficiency by introducing modern techniques, new machinery, a better working environment and a better understanding of the processes used. The need to keep the plant in operation during reconstruction work has caused difficulties, delays and unforseen costs but a close cooperation between all parties concerned (operators, contractors, engineers and the regional environment administration) has solved most of the problems. Experiences so far include an improved effluent quality, a better cost efficiency, a healthier and more engaged operating staff. A research team has been engaged to develop and introduce a nitrogen reduction scheme in the activated sludge process. This has been a challenging and fruitful experience.

Treatment of tunnel wash water and implications for its disposal

2014 ◽  
Vol 69 (10) ◽  
pp. 2029-2035 ◽  
Author(s):  
M. Hallberg ◽  
G. Renman ◽  
L. Byman ◽  
G. Svenstam ◽  
M. Norling
Keyword(s):  
Traffic Safety ◽  
Urban Areas ◽  
Suspended Solids ◽  
Treatment Plant ◽  
Particulate Material ◽  
Wash Water ◽  
Polluted Water ◽  
Solids Concentration ◽  
Low Concentrations ◽  
Road Tunnels

The use of road tunnels in urban areas creates water pollution problems, since the tunnels must be frequently cleaned for traffic safety reasons. The washing generates extensive volumes of highly polluted water, for example, more than fivefold higher concentrations of suspended solids compared to highway runoff. The pollutants in the wash water have an affinity for particulate material, so sedimentation should be a viable treatment option. In this study, 12 in situ sedimentation trials were carried out on tunnel wash water, with and without addition of chemical flocculent. Initial suspended solids concentration ranged from 804 to 9,690 mg/L. With sedimentation times of less than 24 hours and use of a chemical flocculent, it was possible to reach low concentrations of suspended solids (<15 mg/L), PAH (<0.1 μg/L), As (<1.0 μg/L), Cd (<0.05 μg/L), Hg (<0.02 μg/L), Fe (<200 μg/L), Ni (<8 μg/L), Pb (<0.5 μg/L), Zn (<60 μg/L) and Cr (<8 μg/L). Acute Microtox® toxicity, mainly attributed to detergents used for the tunnel wash, decreased significantly at low suspended solids concentrations after sedimentation using a flocculent. The tunnel wash water did not inhibit nitrification. The treated water should be suitable for discharge into recipient waters or a wastewater treatment plant.

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.

Estimation of suspended solids concentrations in activated sludge settling tanks

1997 ◽  
Vol 35 (8) ◽  
pp. 127-135 ◽  
Author(s):  
Youngchul Kim ◽  
Wesley O. Pipes ◽  
Paul-Gene Chung
Keyword(s):  
Activated Sludge ◽  
Suspended Solids ◽  
Marked Effect ◽  
Treatment Plant ◽  
Accurate Method ◽  
Volume Index ◽  
Sludge Volume Index ◽  
Solids Concentration ◽  
Exponential Decrease ◽  
Sludge Settling

This is a report of a field study based on data from an activated sludge process in a wastewater treatment plant in Chester, Pennsylvania, USA. The objective was to develop an accurate method for estimation of the average suspended solids concentration (SSB) of the layer of sludge in the settling tanks (the “sludge blanket”). Plant operators estimated SSB by averaging the mixed liquor suspended solids (Sm) and the return sludge suspended solids (Su) concentrations. Measurement of SSB showed that averaging Sm and Su frequently overestimated SSB by a large amount. A different relationship between SSB and parameters which are normally measured for operational purposes was developed. The parameters are Su, the overflow rates and data from the sludge volume index (SVI) measurement. It was found that an increasing overflow rate will result in an exponential decrease in the ratio of SSB to Su. Also, the SVI has a marked effect on the ratio of SSB to Su and thus on the amount of suspended solids which can be stored in the settling tanks. The proposed estimation equation was found to be statistically superior to estimation by averaging the Sm and Su.

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