Presentation 29. april 2009Presentation 29. april 2009

Model-based optimization of the water treatment of recirculated

fish farms

Kenneth F. Janning

Content of presentation

What is a recirculated fish farm?What is a recirculated fish farm?

Process water treatment technologies used Process water treatment technologies used

in recirculated fish farmsin recirculated fish farms

Market potentialsMarket potentials

Why use of biofilters in recirculated fish Why use of biofilters in recirculated fish

farmsfarms

Identified bottlenecks Identified bottlenecks

ModelModel--based optimisationbased optimisation

R & D R & D

What is a recurculated fish farm?

Problem:Problem:

Water Quality (fish)Water Quality (fish)

Water Quality (water Water Quality (water

treatment kinetics)treatment kinetics)

TAN TAN mg (NHmg (NH44--N+NHN+NH33--N)/lN)/l

QQinin QQoutout

Fish tankFish tank

FiltrationFiltration

Biological water Biological water

treatmenttreatment

QQininmm33/d/d

Recirculated fish farms

37

Sludge deposit

Aeration

2

104

1

5

COD89

11

6

Microfiltration

UV treatmentFiltration CO2 stripping

NH4

Biological COD removal

Nitrification

Sludge dewatering

Fish tanks

Treatment technologies used in fully recirculated fish farms

Denitrification

IT

Market potential, Aquaculture

Aquaculture production of fish in 1970: 0.7 kg/capita*

Production of fish in 2006: 7.6 kg/capita (6.9% annual growth production) or 51.6 mio. tons per year*

Production of fish in land-based and sea- based production facilities in 2008 constitutes more than 50% of the total fish consumption*

Growth in world population and reduction in natural fish capture will lead to investments in Aquaculture in the range of 20-40 Bill. USD within the next 20 years*

Danish Aquaculture production to be increased from 40,000 tons/year (today) to 115,000 tons/year in 2015

*FAO State of the world fisheries and aquaculture, 2008

Why use biofilm technology in Aquaculture

AdvantagesAdvantages

Biofilters are ideal for removal of soluble substancesBiofilters are ideal for removal of soluble substances

Biofilters can maintain its biological capacity under Biofilters can maintain its biological capacity under

variable nutrient and flow conditionsvariable nutrient and flow conditions

The slowgrowing nitrifiers do not get washed outThe slowgrowing nitrifiers do not get washed out

Compact and simple designCompact and simple design

Integration of several processes like cooling, COIntegration of several processes like cooling, CO22stripping, aeration and aerobic oxidation stripping, aeration and aerobic oxidation

Why use biofilm technology in Aquaculture

DisadvantagesDisadvantages

Nitrification sensitive towards organic overloadNitrification sensitive towards organic overload

Overgrowth of media (biofilm control)Overgrowth of media (biofilm control)

Detachment (biofilm control)Detachment (biofilm control)

Long innoculation periodLong innoculation period

Diffusion limited reaction rates limits the efficiency Diffusion limited reaction rates limits the efficiency

when biofilters needs to keep ammonia concentration when biofilters needs to keep ammonia concentration

very lowvery low

Which types of biofilters is being used in Aquaculture

Trickling filtersTrickling filters

Submerged fixedSubmerged fixed--bed filtersbed filters

Moving bed biofilm reactors (MBBR)Moving bed biofilm reactors (MBBR)

Fluidized bed filtersFluidized bed filters

Water Quality Demand in Aquaculture

E.H.Eding et al. (2006). E.H.Eding et al. (2006). Design and operation of nitrifying trickling filters in recirculDesign and operation of nitrifying trickling filters in recirculating ating

aquaculture: A reviewaquaculture: A review. Aquaculture Engineering, vol.34, pp. 234. Aquaculture Engineering, vol.34, pp. 234--260260

Relation between Water Quality Demand and biofilter kinetics

E.H.Eding et al. (2006). E.H.Eding et al. (2006). Design and operation of nitrifying trickling filters in recirculDesign and operation of nitrifying trickling filters in recirculating ating

aquaculture: A reviewaquaculture: A review. Aquaculture Engineering, vol.34, pp. 234. Aquaculture Engineering, vol.34, pp. 234--260260

rrAA= 0,25 gTAN/m= 0,25 gTAN/m22/d /d necessarynecessary = 100 = 100 mm22rrAA= 0,22 gTAN/m= 0,22 gTAN/m22/d /d necessarynecessary = 113 = 113 mm22rrAA= 0,14 gTAN/m= 0,14 gTAN/m22/d /d necessarynecessary = 178 = 178 mm22

Load variation (COD, NH4-N) in AquacultureProblem, load variationProblem, load variation

Addition of easily degradable organic matter, heterotrophic Addition of easily degradable organic matter, heterotrophic

bacteria grows up quicklybacteria grows up quickly

As a rule of thumb, when BODAs a rule of thumb, when BOD5 5 > 5> 5OO22 organic matter penetrates organic matter penetrates

the biofilm further than oxygen which removes the possibility fothe biofilm further than oxygen which removes the possibility for r

the nitrifying biofilm from growingthe nitrifying biofilm from growing

Overgrowth of a nitrifying biofilmOvergrowth of a nitrifying biofilm

Population dynamics in Aquaculture biofilters

Population dynamics in Aquaculture biofilters

Bovendeur et al. (1990). Bovendeur et al. (1990). FixedFixed--biofilm reactors in aquacultural water recycle systems: Effect obiofilm reactors in aquacultural water recycle systems: Effect of organic f organic

matter elimination on nitrification kinetics. Water Research, vomatter elimination on nitrification kinetics. Water Research, vol.24, No. 2, pp. 207l.24, No. 2, pp. 207--213213

Rate of nitrification

g NH4-N/m2/d

TemperatureAlkalinity and pH

Load variation (fish feed)

COD concentration

Hydraulics

Surface efficiency

Biofilter media

O2-concentration

NH4-N concentration

Why use modeling for recirculated fish farms?

Purpose of model-based modelling

Challenges Biological water treatment in recirculated Aquaculture

Understanding of pollution load and treatment performance (fish-feed strategy vs. Biofilter kinetics)

How to obtaining constant Water Quality in aquaculture plants

Improved operation strategies (monitoring and control)

Better treatment technologies

Model-based optimisation a powerful tool to test operation strategies, control, cost of operation etc., but most of all it is a strong learning tool for almost any user

Recirculated aquaculture biofilm model (WEST)

Multilayer (10) dynamic biofilm model

1D biofilm model

Transport into biofilm by diffusion

Attachment-detachment processes included

Dynamic biofilm thickness prediction

Hydraulic film diffusion included

All ASMs can be used (bacterial Monod kinetics applied)

Advantage-disadvantage using the WEST biofilm model

Challenges

Complicated to configure (manual or guide needed for quick configuration)

Model speed quite slow compared to activated sludge modelling (but maybe quick compared to other biofilm model simulators

Biofilm model calibration methods...

Benefits

Very user-friendly process interface

Possibility to visualise any concentration or component interactively

Possibility to control the model dynamically

Advanced multi-layer biofilm model

Excellent lear ning tool for scientists, consultants and operators

FP1: GeosminAAU Biotek

FP2: CFD Hydraulic model of recirculated

aquaculture plantAAU Construction

FP3: Processmodel of recirculated aquaculture

plantDTU E&R

TP1: Microbiologic transformation of GeosminTI, aquaculture plants

Research projects:

Technology projects:

TP2: New treatment technologiesDHI, Billund, AKVAgroup, Inter Aqua Advance, Hydrotech

Siemens..

TP3:Monitoring and control

DHI, Oxyguard, Siemens, Bioras

Possible coorporation with foreign university

Innovation Consortium - REFA

Proces modeling project, main activities

Innovation Consortium - REFA

Develop a new ASM modelmatrix specially designed for processes in Aquaculture, including:

1.Carbonate system (CO2 prediction)2.pH prediction based on most dominant buffer systems3.Calculation of ammonia gas concentration4.Use of particle size distribution instead of just soluble/particulate (S and X in ASM)5.Addition of particle dissolve processes 6.Develop new treatment processes like mecanic filtration and gas stripping that can be incorporated in WEST7.Calibrate and validate the developed mathematical model for general engineering use

Thank you for your attention!