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First IWA-Bulgarian Young Water Professionals First IWA-Bulgarian Young Water Professionals ConferenceConference

WASTEWATER TREATMENT TECHNOLOGIES – STATE OF WASTEWATER TREATMENT TECHNOLOGIES – STATE OF ARTART

Prof. D.Sc. Eng. Roumen ArsovProf. D.Sc. Eng. Roumen ArsovUniversity of Architecture, Civil Engineering and GeodesyUniversity of Architecture, Civil Engineering and Geodesy

Bulgarian Water AssociationBulgarian Water Association

Sofia, 17 May 2012Sofia, 17 May 2012

Wastewater Treatment technologies – State of ArtWastewater Treatment technologies – State of Art

The term “Best Available Technologies” – BAT is in use more The term “Best Available Technologies” – BAT is in use more than 20 years, but it was legally introduced by the Water than 20 years, but it was legally introduced by the Water Framework Directive Framework Directive 2000/60/ЕС2000/60/ЕС, Article 10, 2(a)., Article 10, 2(a).

DefinitionsDefinitions Technologies, insuring achievement of the standards Technologies, insuring achievement of the standards

requirements and being proved their technical, economical and requirements and being proved their technical, economical and social efficiency.social efficiency.

““Best Available Technique is the most efficient and most Best Available Technique is the most efficient and most progressed stage in development of the applied technology of progressed stage in development of the applied technology of wastewater treatment which was developed in such a scale wastewater treatment which was developed in such a scale enabling the employment of the technology under enabling the employment of the technology under economically, economically, socially and technicallysocially and technically acceptable conditions and it is at the acceptable conditions and it is at the same time the most effective technique for water protection” same time the most effective technique for water protection” (according to the Czech Republic governmental Decree No (according to the Czech Republic governmental Decree No 227/2007227/2007).).

PPrinciples of contemporary wastewater treatment technologies are known rinciples of contemporary wastewater treatment technologies are known for about a century and the term “contemporary” nowadays concerns plenty for about a century and the term “contemporary” nowadays concerns plenty of of technological arrangements (layouts)technological arrangements (layouts) and and constructive modificationsconstructive modifications of of the relevant technological units, stimulated by the relevant technological units, stimulated by developments in ecological developments in ecological and technical standards, materials, equipment and construction technologies and technical standards, materials, equipment and construction technologies

Biological Wastewater Treatment TechnologiesBiological Wastewater Treatment Technologies are in the core of the are in the core of the contemporary Best Available Technologies (BAT), applicable to municipal contemporary Best Available Technologies (BAT), applicable to municipal wastewater treatment wastewater treatment

The following two main divisions of municipal wastewater biological The following two main divisions of municipal wastewater biological treatment are in use nowadaystreatment are in use nowadays::

Intensive BiotechnologiesIntensive Biotechnologies With suspended biomassWith suspended biomass With attached biomassWith attached biomass

Extensive BiotechnologiesExtensive Biotechnologies Constructed wetlandsConstructed wetlands Biological lakes and lagoonsBiological lakes and lagoons Send bed trickling filtersSend bed trickling filters Hybrid biological systemsHybrid biological systems

Intensive Biotechnologies with Suspended BiomassIntensive Biotechnologies with Suspended Biomass

Principal layout of activated sludge systemPrincipal layout of activated sludge system

Principal layout of nitrogen and phosphorus biological removalPrincipal layout of nitrogen and phosphorus biological removal

Anaerobicbioreaktor

Anoxycbioreactor

Aerobicbioreactor

Secondary

Clarifier

Recirculation of NO3-

Recirculation of activated sludge

Principal layout of nitrogen biological removal and phosphorus chemical Principal layout of nitrogen biological removal and phosphorus chemical precipitation precipitation

Anoxicbioreactor

Aerobic bioreactor Secondarycalrifier

Recirculation of NO3-

Recirculation of activated sludge

Al2(SO4)3

Intensive Biotechnologies Intensive Biotechnologies with Suspended Biomasswith Suspended Biomass

General view of aerated tank - construction type “Carousel”General view of aerated tank - construction type “Carousel”

General view of aerated tanks – construction type “Plug flow”General view of aerated tanks – construction type “Plug flow”

Scheme of Sequencing Batch Reactor - SBRScheme of Sequencing Batch Reactor - SBR

General view of aerated tanks – technological typeGeneral view of aerated tanks – technological type SBR SBR

(Hisarya WWTP, Bulgaria)(Hisarya WWTP, Bulgaria)

Scheme of membrane biological reactor - MBRScheme of membrane biological reactor - MBR

Membrane Biological Reactor (MBR) construction Membrane Biological Reactor (MBR) construction

Scheme (left) and general view (right) of Upflow Sludge Blanket Reactor – USBRScheme (left) and general view (right) of Upflow Sludge Blanket Reactor – USBR

Scheme of granule biomass – bioreactor type USBRScheme of granule biomass – bioreactor type USBR

Recommended most efficient area of application of aerobic and anaerobic Recommended most efficient area of application of aerobic and anaerobic biotechnologiesbiotechnologies

Intensive Biotechnologies Intensive Biotechnologies with Attached Biomasswith Attached Biomass

Technological layout of trickling filterTechnological layout of trickling filter

General view of trickling filter with plastic carrierGeneral view of trickling filter with plastic carrier

General view of trickling filter with reactive distribution systemGeneral view of trickling filter with reactive distribution system

Scheme of rotating biological contactors – RBCScheme of rotating biological contactors – RBC

General view of Rotating Biological Contactors (RBC)General view of Rotating Biological Contactors (RBC)

Moving Bed Biological Reactor (MBBR) construction Moving Bed Biological Reactor (MBBR) construction

Extensive BiotechnologiesExtensive Biotechnologies

EU COMPENDIUMEU COMPENDIUM forfor

Design and construction ofDesign and construction ofextensiveextensive wastewater wastewater

treatment technologies for treatment technologies for small settlements small settlements (500 - 5000 (500 - 5000 PEPE))

Extensive Biotechnologies with Suspended BiomassExtensive Biotechnologies with Suspended Biomass

Schemes of facultative lagoon (left) and Schemes of facultative lagoon (left) and biological lakes cascade (right)biological lakes cascade (right)

Extensive Biotechnologies with Suspended BiomassExtensive Biotechnologies with Suspended Biomass

General view of aerobic and anaerobic biological lakes and General view of aerobic and anaerobic biological lakes and lagoonslagoons

Extensive Biotechnologies with Attached BiomassExtensive Biotechnologies with Attached Biomass

Scheme of send bed trickling filterScheme of send bed trickling filter

Technological schemes of constructed wetlandsTechnological schemes of constructed wetlands with vertical flow (top)with vertical flow (top)

with horizontal flow (down)with horizontal flow (down)

Scheme (left) and general view (right) of Scheme (left) and general view (right) of constructed wetlandsconstructed wetlands

Driving Forces for Best Available Technologies (BAT) Driving Forces for Best Available Technologies (BAT) DevelopmentDevelopment

LegislationLegislation Historical trend for pollution removal: SS, BOD, N and P (up to Historical trend for pollution removal: SS, BOD, N and P (up to

now), pharmacy micro pollutants (under investigations), S (future)now), pharmacy micro pollutants (under investigations), S (future)

Climate change and water stress – a prerequisite for:Climate change and water stress – a prerequisite for: Change of paradigm: from “wastewater as a problem” towards Change of paradigm: from “wastewater as a problem” towards

“wastewater as a resource”“wastewater as a resource” Stimulation of wastewater recycling and reuse technologiesStimulation of wastewater recycling and reuse technologies Stimulation of decentralized sewer systems developmentStimulation of decentralized sewer systems development Urine separation and treatment technologiesUrine separation and treatment technologies

Requirements for energy efficiencyRequirements for energy efficiency

Is there a rational sense in wastewater reuse?Is there a rational sense in wastewater reuse?

Necessary water for food productionNecessary water for food production - - 1000 1000 mm33/PE/PE..yearyear

Necessary water for drinkingNecessary water for drinking - - 1 1 mm33/PE/PE..yearyear

Municipal wastewater productionMunicipal wastewater production – – 30 - 6030 - 60 mm33/PE/PE..yearyear

There is a rational sense in water resources pollution There is a rational sense in water resources pollution prevention, prevention, becausebecause

Untreated wastewater would pollute the following natural Untreated wastewater would pollute the following natural water resources volumes (in BODwater resources volumes (in BOD55 base) base): :

AboutAbout 11 000 – 20 000 11 000 – 20 000 mm33//PEPE..yearyear in sensitive zonesin sensitive zones

AboutAbout 5 000 5 000 – – 10 000 10 000 mm33//PEPE..yearyear in less sensitive zonesin less sensitive zones

ThereforeTherefore, , 1 1 PEPE would pollute fromwould pollute from 90 90 toto 750 750 times more times more natural water resoursecenatural water resoursece than these used for potable than these used for potable needsneeds (100 – 180 (100 – 180 ll//capcap..dd))

Necessity ofNecessity of wastewater recycling and reusewastewater recycling and reuse stimulates stimulates technologies development for their treatmenttechnologies development for their treatment

Scheme of general concept for wastewater recycling and reuseScheme of general concept for wastewater recycling and reuse

General view of infiltration ponds (California)General view of infiltration ponds (California)

Scheme of urine separation systemScheme of urine separation system

Tendency for WWTPs energy efficiencyTendency for WWTPs energy efficiency

General view of co-generation devices for biogas utilizationGeneral view of co-generation devices for biogas utilization

What is the share of the wastewater energy potential in What is the share of the wastewater energy potential in respect to overall energy consumption per 1 PErespect to overall energy consumption per 1 PE? ?

((some figures bysome figures by K. Svardal & H. Kroiss, WS&T, 2011K. Svardal & H. Kroiss, WS&T, 2011))

Specific power consumption on the base of focil fuelSpecific power consumption on the base of focil fuel - - 5-10 5-10 kW/PEkW/PE

Specific power in human food consumptionSpecific power in human food consumption - - 0,11 0,11 kW/PEkW/PE

Specific power in polluted wastewaterSpecific power in polluted wastewater - - 0,0225 0,0225 kW/PEkW/PE

OnlyOnly 5 % 5 % of wastewater of wastewater heat recuperationheat recuperation is economically feasible is economically feasible

Therefore wastewater can not be considered as a reliable source of Therefore wastewater can not be considered as a reliable source of energy since they content energy since they content no more thanno more than 0,44 % 0,44 % of domestic energy of domestic energy consumption of 1 PEconsumption of 1 PE

What is the share of the wastewater energy potential in What is the share of the wastewater energy potential in respect to overall energy balance of the WWTPrespect to overall energy balance of the WWTP

Specific power for aeration at the big Specific power for aeration at the big ( (overover 50 000 50 000 PEPE) ) WWTPs, WWTPs, depending of the technology applieddepending of the technology applied – – 1,0-1,9 1,0-1,9 W/PEW/PE (3 - (3 - 1515 W/mW/m33))

Total specific power at the bigTotal specific power at the big ( (overover 50 000 50 000 PEPE) ) WWTPs, depending WWTPs, depending of the technology appliedof the technology applied – – 1,7-3,1 1,7-3,1 W/PEW/PE

Specific power in polluted wastewaterSpecific power in polluted wastewater - - 22,5 22,5 W/PEW/PE

Specific electric power which could be obtained by biogas Specific electric power which could be obtained by biogas utilization,utilization, depending of the technology applieddepending of the technology applied – – 0,9-2,1 0,9-2,1 W/PEW/PE ((with with 25-37%25-37% co-generators efficiency) co-generators efficiency)

Стремеж към енергийна ефективностСтремеж към енергийна ефективност

What is the share of the wastewater energy potential in What is the share of the wastewater energy potential in respect to overall energy balance of the WWTP - respect to overall energy balance of the WWTP -

continuationcontinuation

Therefore at big WWTPsTherefore at big WWTPs ( (overover 50000 50000 PEPE)),, utilization of the biogas utilization of the biogas for electricity production is technically possible and economically for electricity production is technically possible and economically feasible,feasible, for covering of the vast of the power needsfor covering of the vast of the power needs

Generated electricity production could be increased byGenerated electricity production could be increased by:: Increasing of organic content of the sludge, treated in the high rate Increasing of organic content of the sludge, treated in the high rate

digesters by stimulation of primary sedimentationdigesters by stimulation of primary sedimentation Optimization of design of the high rate digestersOptimization of design of the high rate digesters Increasing of the co-generators efficiencyIncreasing of the co-generators efficiency

At the middle sized and small WWTPsAt the middle sized and small WWTPs ( (underunder 20 000 20 000 PEPE) ) the the energy balance is negativeenergy balance is negative - ( - (fromfrom -27 -27 toto -32 -32 W/PEW/PE), ), which makes which makes biogas capture and utilization economically infeasiblebiogas capture and utilization economically infeasible

BASIC FEEDBACK AND CONCLUSIONSBASIC FEEDBACK AND CONCLUSIONS

““Best Available Technologies” (BAT) are these, which are implemented in Best Available Technologies” (BAT) are these, which are implemented in the current practice, based on advanced technological achievements the current practice, based on advanced technological achievements

Technological processes, applied with the BAT are known for about a Technological processes, applied with the BAT are known for about a century and the term century and the term “new”“new” concerns mainly concerns mainly the plenty of technological the plenty of technological modifications, based on modifications, based on developments in legislation, materialsdevelopments in legislation, materials, , construction technologies and equipmentconstruction technologies and equipment

The most power factors influencing BAT development is legislationThe most power factors influencing BAT development is legislation

Ecological and technological standardsEcological and technological standards developments are the most developments are the most influencing factors for stimulation of the BAT development in comparison influencing factors for stimulation of the BAT development in comparison with these of “climate change” and “wastewater as energy and fresh water with these of “climate change” and “wastewater as energy and fresh water resourceresource

Trends towards achievement of the WWTPs energy efficiency is a Trends towards achievement of the WWTPs energy efficiency is a contemporary icontemporary imperativemperative

The WWTP energy consumption depends mainly on the pollution load The WWTP energy consumption depends mainly on the pollution load rather than on wastewater flowrate rather than on wastewater flowrate ((Briscoe, Wasser-Abwasser, 1995)Briscoe, Wasser-Abwasser, 1995)

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