research developments in the on-site treatment of...

Research developments in the on-site treatment of wastewater

Dr. Edmond O’Reilly – [email protected] Dr. Eoghan Clifford – [email protected] Mr. Shane Fox (NUI Galway) Dr. Michael Rodgers (RMEnv Ltd) http://www.nuigalway.ie/civileng/Facilities/tuam/index.html

College of Engineering and Informatics Ryan Institute for Environment, Marine and Energy Research

mailto:[email protected]�

mailto:[email protected]�

http://www.nuigalway.ie/civileng/Facilities/tuam/index.html�

Overview

– Background – Nutrient removal on-site

• Nitrogen; phosphorous

– On-site disinfection – Pilot scale test facilities

• Water Research Facility; Other on-site facilities

– Technology development

– The future …


Background – on-site wastewater treatment systems


Single house systems Larger on-site systems Conventional septic tank + percolation

Secondary treatment systems Secondary treatment systems

Secondary treatment with tertiary treatment Secondary treatment with tertiary treatment

Generally groundwater discharge Generally surface water discharge

Guidelines: CEN 12566; EPA Code of Practice for single houses (2010)

Guidelines: EPA Code of Practice: WWT systems for communities, business, leisure centres and hotels (1999)

Water Services (Amendment) Act 2012: Registration of domestic wastewater treatment systems

Wastewater Discharge (Amendment) regulations 2010: Discharges above 5 m3/day licensed/authorised by EPA

Background – drivers and legislation

– Water Framework Directive (2000/60/EC) – “New Groundwater Directive”(2006/118/EC) – Challenges include

• Maintain or restore water bodies to “good status” – Nitrogen, phosphorous and pathogens of concern.

• Quality of drinking water abstracted; particularly from private wells

• Need for low maintenance, low energy systems that can achieve required standards

• Areas where difficult on-site conditions prevail

• Monitoring: what, how frequently and where?


Nutrient removal - nitrogen

– Not always required though often necessary near sensitive waters – Two step removal process

• 1: Conversion of ammonium-nitrogen (NH4-N) to nitrate-nitrogen (NO3-N); – Nitrification (require low carbon and high dissolved oxygen)

• 2: Conversation of nitrate-nitrogen (NO3-N) to nitrogen gas (N2) – Denitrification (require electron donor and low dissolved oxygen)

– Can occur in percolation systems • lack of organic carbon and subsoil permeability can be limiting factors

– Package WWTPs can be specifically designed to achieve denitrification • low cost biofilm process; where carbon is limiting ….


Nutrient removal – nitrogen horizontal flow biofilm reactor (HFBR)

Septic tank or primary settled influent

Step feed: • approx 33% daily flow • introduced about ⅔ down the depth of the reactor

About 67% daily flow pumped onto the top sheet

0.5 – 1.8 m deep



– Minimal mechanical parts → low energy and low maintenance

– Easily upgraded from nitrification to denitrification system

– With a step feed mechanism carbon in the influent wastewater can be used as an electron donor

– Total energy costs: € 0 - 20/year



– Minimal mechanical parts → low energy and low maintenance

– Easily upgraded from nitrification to denitrification system

– With a step feed mechanism carbon in the influent wastewater can be used as an electron donor

– Total energy costs: € 0 - 20/year

BOD5 (COD) TN

System Loading rate (g/m2/d) % removal Loading rate

(g/m2/d) % removal

HFBR 141.5 97.4 15.7 61.7 RF with forced aeration (5.6) 73 - -

St Sand Filter 22 99 2.4 27 Soil Filter with added

carbon layer 8.4 83 - 93 1.8 67

Constructed wetlands - - 8.1 – 14.1 55 - 80


Nutrient removal – nitrogen where carbon is limiting

– Where carbon is limiting recent work has focused on the use of, and economics of alternative electron donors

• Organic media (woodchip, biopolymers, cardboard …)

• Autotropic denitrification – use of sulphur-based media)

Septic tank effluent/ primary settled WW

Secondary treatment system (media can be used at this stage also)

Denitrifying Reactor (carbon or sulphur based media)

Effluent / further treatment

Areas for research • Cost of media • Replacement frequency • Ease of reactor operation • Need for recirculation – and thus higher energy costs


Nutrient removal - phosphorus


– Sensitive areas – Discharge to (or close to) a water source

– High up within a catchment

– Two removal mechanisms in on-site wastewater treatment • 1: Biological removal of phosphorus

– P uptake through plant growth (limited removal)

• 2: Physical/chemical removal of phosphorus – Adsorption through filter material in wetlands or sand/soil filters

– dedicated adsorption technologies

Pathogen removal

– Not always required though can be necessary when: • discharge near drinking water sources; • discharge to surface waters; • discharge to a highly permeable soil; • discharge near bathing waters or aquaculture farms

– Challenges include: • the provision of cost effective systems, • the cost, frequency and location of monitoring (some parameters are extremely

expensive to monitor) • the necessity for high quality up stream treatment • one technology may not be effective against all pathogens


Pathogen removal

– Technologies • UV technologies • sand and soil filtration • wetlands

– Research • Novel slow sand filters that require reduced maintenance • Use of MBRs and gamma radiation (cost effectiveness being an issue currently) • New monitoring/analysis techniques • Novel pulsed UV technologies

– Work on the maintenance and monitoring requirements that can ensure good performance but are sustainable at a domestic level is required


Overview of the Water Research Facility


PFBR system

2 x primary settlement tanks + balance tank

Pilot scale research



PFBR system


Tertiary treatment processes




PFBR system


Tertiary treatment processes

Control cabin




Human Machine Interface


Human Machine Interface

• Human Machine Interface • Full automation of plant • Live readings from all sensors • Data logging • Remote interrogation/operation


• Plug and play design • Fully automated • Manual and automatic sampling • Media filtration

• Sand • Activated carbon

• Adsorption columns • Disinfection • Novel technologies – seaweed, new chlorine systems etc




• Testing of new screens, filters etc. • Test secondary wastewater treatment systems

Raw/primary treated wastewater

• Test new water/wastewater tertiary treatment systems

• Development of new sensor and control equipment

Secondary treated wastewater

• Development of disinfection systems • Overall water/wastewater facility energy

management/efficiency

Tertiary treated wastewater (similar to source water for

drinking water)

• Access to primary and secondary sludge • Pilot scale trials on sludge equipment and

sludge to energy technology Sludge & biosolids


In-house technology development (facilitated by having a large scale research site)

Horizontal Flow Biofilm Reactor: single house treatment system – Pilot scale trials at the WRF – Commercially licensed in Europe and USA

Pumped Flow Biofilm Reactor: wastewater treatment system – WRF enabled full scale trials – Current installations in Co. Mayo (200PE) and Moneygall Co. Offaly (750PE) – Commercial license at an advanced negotiation stage

Air Suction Flow Biofilm Reactor: wastewater treatment system – Pilot scale trial underway @ 2 sites (1 of which is the WRF)

Samplers: novel water sampling devices – patent application underway – Work at the WRF and Newport, Co. Mayo led to this concept

Sensors/WWTP control systems – patent disclosure underway



Pumped Flow Biofilm Reactor: wastewater treatment system – Moneygall Co. Offaly (750PE)

– Collaboration between

• 3rd level institution

• industrial partner

• local authority





Advantages of the PFBR: • Low energy requirement • Low maintenance requirement • Low sludge yield • Ease of operation • Stable process

Parameter Influent Balance Tank

Effluent Clarifier

% removal

Biochemical oxygen demand 5-day (BOD5) 163 (44.2) 4 (4.6) 98%

Suspended solids (SS) 141 (95.8) 5 (4.9) 97%

Ammonium-nitrogen –filtered (NH4-N) 10.0 (2.2) 2.9 (1.2) 71%

Nitrate-nitrogen – filtered (NO3-N) - 5.5 (1.4) -

Total Nitrogen – unfiltered (TNt) 13.6 (2.5) 10.6 (1.3) 22%



– Initial results (after two months operation)


Estimated biological load: 578PE (@ 40 g BOD/PE.d) Estimated energy usage: 21 kWh/PE.yr (or € 3.60/PE.yr @ € 0.17/kWh)

Possible focus for further research and developmental work

Nitrogen removal:

– The use of passive technologies, with step-feed mechanisms to achieve nitrogen removal

– The potential of primary settled solids as a carbon source for denitrification

– The use of biodegradable polymers as a carbon source for denitrification

– Further development of autotrophic denitrification processes



Phosphorous removal:

– Significant work is required on the use of adsorption materials for on-site phosphorous removal. The logistics and cost of media replacement can be

– Biological phosphorous removal processes require further development before widespread use in single house wastewater treatment systems



Pathogen removal:

– Technology combinations that could enable discharge of on-site effluents to surface waters

– Improved pre-treatment of wastewaters to ensure effective pathogen removal

– Development of cost-effective monitoring of systems where disinfection is required

– Further work on the development of filtration technologies as effective means of pathogen removal


Examples of technology development/validation with industry

• Low temperature anaerobic digestion for wastewater treatment (NUI Galway Microbiology technology/EI Funding)

• Bioplastics and their use in the waste/water sectors (Littlefoot Ltd/NUI Galway Collaboration)

• Verification of a new wastewater technology for domestic and small scale wastewater installations (NUI Galway/Georgia Tech Ireland/Waterloop Ireland Ltd/ EI Funding)

Initial M & E testing before final deployment

Full testing for technology verification


• Efficiency of a new DAF system for wastewater treatment (Kensol Ltd/EI Funded) • Verification of a phosphorous adsorption system for wastewater treatment (CWT Ltd/EI

Funded) • A new rapid sand filter, that minimises down time at wastewater treatment facilities

(AquaSol Ltd/EI Funded) • A new slow sand filter for water and wastewater treatment (Lir Water Treatment Ltd/EI

Funded)

Technology design & operation optimisation

Measure and reduce energy costs, maintenance


Examples of technology development/validation with industry

Examples current research projects in the water/wastewater area at NUI Galway

• Comparison of disinfection technologies with a focus on developing new methods for virus detection (NUI Galway, Marine Institute AIT – EPA Funded)

• Development of a pulsed-UV system for emphasising cryptosporidium removal (AIT, NUI Galway – EPA Funded)

• Treatment of odours and gases using a novel biological reactor (SFI Funded) • Development of new sensors with control algorithms for water & wastewater treatment

plants (EI Funded Feasibility Study)


• Commercial scale PFBR system at Moneygall, Co. Offaly (EI Funded) • Real time remote control of WWTPs, with an emphasis on meeting discharge limits using pH,

ORP, Conductivity and O2 sensors (IRCSET Funded) • Development of new mathematical models for the passive aeration systems such as the

PFBR and ASF-BR (NUI Galway Funded) • Dewatering and subsequent energy generation from waste biosolids; development of new

dewatering techniques (EI/NUI Galway Funded)


Examples current research projects in the water/wastewater area at NUI Galway

Other ongoing projects (both fundamental research and applied commercial research)

Summary of research areas/potential collaboration

Fundamental understanding required (nutrient

removal/recovery, emerging contaminants …)

Microbial ecology/chemistry studies can enable

better engineering of reactors

Applied research and technology

development /optimisation

Meeting wastewater discharge limits while

reducing costs?

Enabling of real time control and

monitoring (e.g. Virtual sensors)

Sludge/Biosolids treatment and energy

recovery

New materials & nanomaterials with

Vast potential in water/wastewater

treatment


Main funding modes/research links & collaborating organisations



Thank you

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