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.

Biological odour control by diffusion into activated sludge basins

2000 ◽  
Vol 41 (6) ◽  
pp. 127-132 ◽  
Author(s):  
R. P. Bowker
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
High Strength ◽  
Air Stream ◽  
Fine Bubble ◽  
Treatment Facilities ◽  
Odour Control ◽  
Odour Emissions ◽  
Air Streams

Diffusion of odourous air into activated sludge basins is an effective and economical approach for odour control at wastewater treatment plants. Over 30 facilities in North America practice this technique. Most of these applications are for dilute or moderate strength air streams with relatively low hydrogen sulfide (H2S) levels. Unfortunately, the lack of data documenting the effectiveness of the process and concerns for blower corrosion have limited its acceptance as a method for controlling odour emissions. This paper presents a compilation and review of wastewater treatment facilities that are currently using activated sludge diffusion. Performance data are tabulated, and information on operation and maintenance of the blower/diffuser systems are summarized. New data are presented that compare the effectiveness of coarse vs. fine bubble diffusers for treatment of a high strength, high-H2S air stream from sludge holding tanks at Concord, NH. Designand performance information is presented on a dedicated odour control system installed at Phoenixville, Pennsylvania in 1996 that collects high-H2S air streams from an influent chamber and primary clarifiers and diffuses it into a mechanically-aerated activated sludge basin. A cost-effectiveness analysis is presented for a blower/diffuser system installed exclusively for odour control. Methods used to overcome initial operational problems are discussed.

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.

scholarly journals Activated Sludge Systems as Diferential Equations: A Fresh View on the Classical Models for Wastewater Treatment Plants

2014 ◽  
Vol 6 (2) ◽  
pp. 49-53
Author(s):  
Horea Olosutean ◽  
Letiţia Oprean
Keyword(s):  
Wastewater Treatment ◽  
Differential Equations ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Early Stage ◽  
Theory And Practice ◽  
Supplementary Data ◽  
Classical Models ◽  
Activated Sludge Models ◽  
Activated Sludge Systems

Abstract Present in the theory and practice of wastewater treatment for over 50 years in consistent numbers, activated sludge models are widely used by plant operators. The early stage models, based on differential equations were synthetized and reinterpreted, presenting new insides that can help to a better understanding of the processes involved in the wastewater treatment. A consistent symbology is presented, for a much homogenous perspective, and the obvious similarities between several equations from the models are pointed out. The incomplete information from the models is emphasized, showing their amount of providing supplementary data for plant operators and researchers in the field, as well as the causes leading to their drawbacks and the effects derived from these drawbacks.

Feasibility of contact aeration method for small-scale domestic wastewater treatment system in rural China

2012 ◽  
Vol 7 (2) ◽  
Author(s):  
T. Kuyama ◽  
M. Mizuochi ◽  
H. Koyanagi ◽  
T. Wako
Keyword(s):  
Wastewater Treatment ◽  
Rural Areas ◽  
Wastewater Treatment Plants ◽  
Rural China ◽  
Domestic Wastewater ◽  
Treated Wastewater ◽  
Small Scale ◽  
Billing System ◽  
Domestic Wastewater Treatment ◽  
Treatment Facilities

This study examines the feasibility of the contact aeration method for utilisation in small-scale domestic wastewater treatment facilities in various rural areas of China, where the national government starts to address the water pollution issue. Three pilot facilities using the contact aeration method with different capacities were constructed, operated and monitored in Chongqing city and Jiangsu province. In order to evaluate the feasibility of the constructed facilities, the quality of treated wastewater and the operational cost were monitored. Results obtained from the monitoring showed that BOD and COD effluent concentrations achieved quality targets in all facilities. As for the other pollutants, quality targets were met for most of the period. Operational costs of facilities bettered those set for the facility in the town of Baiyang and new village of Zhaojia, but exceeded them for the facility in the village of Dongbei. The main reasons for the differences were the electricity billing system and operational system for each facility. In order to promote small-scale aeration-based domestic wastewater treatment plants in rural China in the future, the issue of what constitutes efficient facility maintenance first needs to be addressed.

scholarly journals Behavior of Glyphosate in Wastewater Treatment Plants

2020 ◽  
Vol 74 (3) ◽  
pp. 156-160 ◽  
Author(s):  
Thomas Poiger ◽  
Martina Keller ◽  
Ignaz J. Buerge ◽  
Marianne E. Balmer
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Surface Waters ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Treated Wastewater ◽  
Excess Sludge ◽  
Strong Adsorption ◽  
Raw Wastewater ◽  
Herbicide Glyphosate

The herbicide glyphosate is frequently detected in surface waters and its occurrence is linked to agricultural as well as urban uses. Elevated concentrations downstream of wastewater treatment plants (WWTPs) suggest that municipal wastewater is an important source of glyphosate in surface waters. We therefore conducted a study at a typical municipal WWTP in Switzerland to characterize the seasonality of glyphosate occurrence, the removal efficiency, and the processes involved in glyphosate removal. Glyphosate was present in raw (mechanically treated) wastewater during the whole study period (April to November). A lab incubation experiment with activated sludge indicated negligible degradation of glyphosate. Lack of degradation combined with strong adsorption lead to substantial enrichment of the compound in the sludge. Due to this enrichment and the long residence time of activated sludge (several days, compared to hours for wastewater itself), concentrations in treated wastewater show comparatively little variation, whereas concentrations in raw wastewater may fluctuate considerably. Overall removal efficiencies were in the range of 71–96%. This behavior could be described qualitatively using a numerical model that included input of glyphosate via raw wastewater, adsorption to activated sludge, and export via treated wastewater and excess sludge, but excluded degradation processes.

scholarly journals Removal and transformation of pharmaceuticals in wastewater treatment plants and constructed wetlands

2013 ◽  
Vol 6 (1) ◽  
pp. 97-117 ◽  
Author(s):  
E. Lee ◽  
S. Lee ◽  
J. Park ◽  
Y. Kim ◽  
J. Cho
Keyword(s):  
Wastewater Treatment ◽  
Constructed Wetlands ◽  
Surface Waters ◽  
Biological Treatment ◽  
Wastewater Treatment Plants ◽  
Wastewater Effluent ◽  
Trace Organic Compounds ◽  
Initial Transformation ◽  
The Stability ◽  
D Value

Abstract. Since trace organic compounds such as pharmaceuticals in surface water have been a relevant threat to drinking water supplies, in this study the removal of pharmaceuticals and transformation of pharmaceuticals into metabolites were investigated in the main sources of micropollutants such as wastewater treatment plants (WWTPs) and engineered constructed wetlands. Pharmaceuticals were effectively removed by different WWTP processes and wetlands. Pharmaceutical metabolites with relatively low log D value resulted in the low removal efficiencies compared to parent compounds with relatively high log D value, indicating the stability of metabolites. And the constructed wetlands fed with wastewater effluent were encouraged to prevent direct release of micropollutants into surface waters. Among various pharmaceuticals, different transformation pattern of ibuprofen was observed with significant formation of 1-hydroxy-ibuprofen during biological treatment in WWTP, indicating preferential biotransformation of ibuprofen. Lastly, transformation of pharmaceuticals depending on their structural position was investigated in terms of electron density, and the electron rich C1 = C2 bond of carbamazepine was revealed as an initial transformation position.

Expansion of Advanced Wastewater Treatment Facilities at Washington, D.C.

1988 ◽  
Vol 20 (4-5) ◽  
pp. 303-313
Author(s):  
W. F. Bailey ◽  
T. G. Shea
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Filter Press ◽  
Fluid Bed ◽  
Treatment Facilities ◽  
Advanced Wastewater Treatment ◽  
Activated Sludge Systems

Advanced wastewater treatment facilities at Washington D.C.'s Blue Plains plant are being expanded and upgraded to provide increased capacity. In order to continue meeting the very stringent discharge limitations, modifications will be made to the secondary and nitrification activated sludge systems, wastewater filters, disinfection system, and plant instrumentation. Major upgrades are planned for sludge processing including construction of centrifuge and filter press dewatering facilities, mechanical composting and fluid bed incineration.

Operational Indicators to Manage the Replacement of Electromechanical Equipment in Wastewater Treatment Facilities

2021 ◽  
pp. 1-20
Author(s):  
Vicent Hernández-Chover ◽  
Lledó Castellet-Viciano ◽  
Francesc Hernández-Sancho
Keyword(s):  
Wastewater Treatment ◽  
Biological Treatment ◽  
Wastewater Treatment Plants ◽  
Replacement Policy ◽  
Optimal Management ◽  
Specific Domain ◽  
Different Types ◽  
Acquisition Costs ◽  
Treatment Facilities ◽  
Electromechanical Equipment

Optimal management is usually at the top of the concerns in the context of water infrastructures. In the specific domain of wastewater treatment plants (WWTPs), European Directive 91/271 established the need of implementing a biological treatment of wastewater leading to an intensive construction of WWTPs in several European countries, which now present important problems of maintenance. These facilities are composed of different types of assets, which should be managed efficiently in order to optimize the performance of the processes as well as the maintenance and replacement costs of the equipment. In fact, the deterioration of these assets increases the operational risk and endangers the continuity of the service of these WWTPs. In this paper, the authors combine multicriteria methodologies (MCDM) and economic aspects of the equipment to define an appropriate technical–economical replacement policy. With the aim of developing a reference procedure in the wastewater sector, an approach has been made to blower pump, which is an equipment widely used in WWTPs to provide a continuous air flow to the reactor facilitating the elimination of organic matter and the nutrients contained in the wastewater. The proposal integrates aspects such as acquisition costs and corrective maintenance, interest rate, and amortization based on the condition of the equipment.

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.

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