Effects of different pairing configurations of woodchips and steel chips in dual media treatment systems on nutrient removal and organics and iron leaching

In a densely populated area, a large wastewater treatment plant (WWTP) has been constructed in the underground. The plant is practically “invisible” to visitors and neighbours, and the ground level is used as a park and sport facilities in order to avoid the “not in my backyard” phenomenon. The WWTP has a 5-stage biological nutrient removal system utilizing the denitrifying PAO (dPAO) with a step feed in order to treat the weak sewage with higher nutrient removal requirement. Although the underground installation could be expected to increase plant operating temperature, the temperature increase was only 1°C. The polished final effluent from a sand filter produced average TN and TP concentrations of 5.11 mg/L and 0.91 mg/L, respectively with SS concentrations of 0.61 mg/L, indicating that the dPAO system combined with sand filter effectively produced a high quality effluent.

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Examples for the Upgrading of Existing Activated Sludge Plants for Nutrient Removal

Water Science & Technology ◽

10.2166/wst.1990.0236 ◽

1990 ◽

Vol 22 (7-8) ◽

pp. 113-121

Author(s):

W. Maier

Keyword(s):

Activated Sludge ◽

Nutrient Removal ◽

Sewage Treatment ◽

West Germany ◽

Sewage Treatment Plants ◽

Effluent Standards ◽

Near Future

In view of the new effluent standards in West Germany, including nitrification and phosphorus elimination, many of the existing sewage treatment plants will have to be rebuilt or expanded. Another demand which will have to be dealt with in the near future is denitrification. Under consideration of the large BOD5-loads which were taken into account when designing the plants, many of them nitrify during the summer or can be easily converted to operate with nitrification. Principles for planning the upgrading of such plants have been laid down in order to achieve the required effluent concentrations. The application of these principles is demonstrated with examples of upgraded plants.

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Upgrading Wastewater Treatment Plants for Biological Nutrient Removal

Water Science & Technology ◽

10.2166/wst.1990.0229 ◽

1990 ◽

Vol 22 (7-8) ◽

pp. 53-60 ◽

Cited By ~ 1

Author(s):

B. Rabinowitz ◽

T. D. Vassos ◽

R. N. Dawson ◽

W. K. Oldham

Keyword(s):

Wastewater Treatment ◽

Nutrient Removal ◽

Wastewater Treatment Plants ◽

Design Flow ◽

Biological Nutrient Removal ◽

Nitrogen And Phosphorus ◽

Conventional Activated Sludge ◽

Recent Developments ◽

Removal Technology ◽

Biological Nitrogen

A brief review of recent developments in biological nitrogen and phosphorus removal technology is presented. Guidelines are outlined of how current understanding of these two removal mechanisms can be applied in the upgrading of existing wastewater treatment plants for biological nutrient removal. A case history dealing with the upgrading of the conventional activated sludge process located at Penticton, British Columbia, to a biological nutrient removal facility with a design flow of 18,200 m3/day (4.0 IMGD) is presented as a design example. Process components requiring major modification were the headworks, bioreactors and sludge handling facilities.

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Optimization of Nutrient Removal in Stockholm

Water Science & Technology ◽

10.2166/wst.1991.0191 ◽

1991 ◽

Vol 24 (7) ◽

pp. 103-111 ◽

Cited By ~ 1

Author(s):

G. Brattberg ◽

L.-G. Reinius ◽

M. Tendaj

Keyword(s):

Nutrient Removal ◽

Sewage Treatment ◽

Water Source ◽

Chemical Precipitation ◽

Phosphorus Load ◽

Sewage Treatment Plants ◽

Limiting Nutrient ◽

Baltic Proper ◽

Mechanical Stage ◽

The Baltic

Stockholm was founded at the point where the waters of Lake Mälaren emerge into the Baltic Sea. Lake Mälaren is the water source of the water works of Stockholm. The Lake also receives water from one of the sewage treatment plants. The outlet from the two other sewage treatment plants are in the inner part of the archipelago. During 1968-73 the treatment was improved, after which the phosphorus load to the receiving water significantly decreased. The total P concentration in the surface water has decreased since 1970 and phosphorus has replaced nitrogen as the most limiting nutrient throughout the entire archipelago within 50 km from Stockholm. To further reduce the eutrophication a continued reduction of the phosphorus load is most effective. For the Baltic proper as a whole, where primary nitrogen limitation is present, it is important to reduce the supply of nitrogen to the greatest possible extent. The treatment plants in Stockholm are located in subsurface rock-chambers. The treatment includes mechanical, biological and chemical treatment. In the mechanical stage the sewage is treated in screens, grit chambers and primary sedimentation. The biological stage is a conventional activated sludgeprocess. For the chemical precipitation ferroussulphateis added before the screens. The sludge is stabilized in anaerobic digesters and dewatered in centrifuges before disposal on farmland. To meet more stringent requirements on nitrification and nitrogen removal several projects are going on to optimize the nutrient removal. The aim of these investigations is to improve the plants' performance within the existing plant.

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Nutrient Removal in Small Wastewater Treatment Plants

Water Science & Technology ◽

10.2166/wst.1990.0203 ◽

1990 ◽

Vol 22 (3-4) ◽

pp. 211-216

Author(s):

Niels Skov Olesen

Keyword(s):

Wastewater Treatment ◽

Nitrogen Removal ◽

Nutrient Removal ◽

Phosphorus Removal ◽

Wastewater Treatment Plants ◽

Ferrous Sulphate ◽

Practical Solution ◽

Sensitive Technique ◽

Pumping Station ◽

Denitrification Reactor

In some areas of Denmark nutrient removal is required even for very small wastewater plants, that is down to 500 pe (pe = person equivalents). The goal for the removal is 80% removal of nitrogen and 90% removal of phosphorus, or in terms of concentrations: 8 mg nitrogen/l and 1.2 mg phosphorus/l. The inlet concentrations are typically 40 mg N/l and 10 mg P/l. The paper presents the results from two such plants with a capacity of 800 pe. Phosphorus removal is made by simultaneous precipitation with ferrous sulphate. Nitrogen removal is carried out using the recirculation method. Both plants were originally rotor aerated oxidation ditches. They have been extended with a denitrification reactor and a recirculation pumping station. At present both plants have been in activity for about 3 years and with satisfactory results. Average concentrations of nitrogen (summer) and phosphorus is 7 mg/l and 0.9 mg/l respectively. Nitrogen removal seems to be a practical solution on these small plants. It is,though, sensitive to temperature and highly oxidized rain water. Phosphorus removal seems to be an easily run and relatively non-sensitive technique at least when using simultaneous precipitation.

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Experiences with sludge settleability in different process alternatives for nutrient removal

Water Science & Technology ◽

10.2166/wst.1996.0321 ◽

1996 ◽

Vol 33 (12) ◽

pp. 137-146 ◽

Cited By ~ 5

Author(s):

Kjær Andreasen ◽

Lars Sigvardsen

Keyword(s):

Nutrient Removal ◽

Plant Layout ◽

Filamentous Microorganisms ◽

Positive Effect ◽

Sludge Settleability ◽

Settling Characteristics ◽

P Removal

SVI and DSVI were measured three times at almost 100 Danish nutrient removal plants and the filamentous microorganisms were subsequently characterized in the laboratory. Information about the plant layout and the operation was collected by means of a questionnaire. In general, the sludge settleability index becomes worse by the introduction of nutrient removal. Among nutrient removal plants the best settling characteristics are found among plants with biological P removal and the poorest among the plants that perform simultaneous denitrification. When compared to iron products, aluminium products in some cases seem to reduce the filament number and improve the settling characteristics in plants that apply simultaneous precipitation for P removal. Selectors may have a positive effect on the filament number but the effect may not be enough to prevent bulking.

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Survey of filamentous populations in nutrient removal plants in four European countries

Water Science & Technology ◽

10.2166/wst.1998.0645 ◽

1998 ◽

Vol 37 (4-5) ◽

pp. 281-289 ◽

Cited By ~ 26

Author(s):

Dick H. Eikelboom ◽

Andreas Andreadakis ◽

Kjaer Andreasen

Keyword(s):

Nutrient Removal ◽

Seasonal Pattern ◽

Plug Flow ◽

Phosphate Removal ◽

Particulate Fraction ◽

Biological Nutrient Removal ◽

Process Conditions ◽

Minor Importance ◽

Filamentous Microorganisms ◽

Short Period

A joint EU research project aimed at solving activated sludge bulking in nutrient removal plants was initiated in 1993. The project started with a survey of the size and composition of the filamentous population in nutrient removal plants in Denmark, Germany, Greece and the Netherlands. The results show that biological nutrient removal process conditions indeed favour filamentous microorganisms in their competition with floc forming organisms. An increase in the size of the filamentous population resulted in a deterioration of the settling properties of the biomass, except for plants with Bio-P removal conditions. It is assumed that in the latter case the dense clusters of Bio-P bacteria increase the weight of the flocs, and compensate for the effect of the larger number of filaments. Although exceptions frequently occur, the following sequence in decreasing filamentous organism population size was observed for the process conditions indicated: - completely mixed + simultaneous denitrification; - completely mixed + intermittent aeration/denitrification; - alternating anoxic/oxic process conditions, with an anaerobic tank for biological phosphate removal (Bio-Denipho); - alternating anoxic/oxic process conditions (Bio-Denitro); - predenitrification The surveys provided little information about the effect of nutrient removal in plants with plug flow aeration basins. Simultaneous precipitation with aluminium salts nearly always resulted in a low number of filaments and a good settling sludge. The size of the filamentous organism population showed a seasonal pattern with a maximum in winter/early spring and a minimum during summer (in Greece: during autumn). This seasonal variation is primarily caused by the effect of the season on the population sizes of M. parvicella, N. limicola and Type 0092. M. parvicella is by far the most important filamentous species in nutrient removal plants. In Denmark only, Type 0041 also frequently dominates the filamentous population, but seldom causes severe bulking. Considering their frequency of occurrence, approx. 10 other filamentous micro-organisms are of minor importance. Growth of some of these species, viz. those which use soluble substrate, can be prevented by the introduction of Bio-P process conditions. M. parvicella and Type 0041 (and probably also Actinomycetes and the Types 1851 and 0092) seem to compete for the same substrates i.e. the influent particulate fraction. Most of the differences in composition of the filamentous microorganism population can be explained by whether or not premixing of influent and recycled sludge is used. In general, premixing for a short period of time followed by anoxic conditions favours Type 0041. M. parvicella seems to proliferate if the particulate fraction is first hydrolysed or if it enters the plant via an oxic zone. It is concluded that bulking in nutrient removal plants is mainly caused by filamentous species requiring the particulate fraction for their growth.

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