Recent Advances in Membrane Technology Dr Bob Lovitt Swansea University - Membranology Ltd Pressure driven Membrane technologies Current markets

• Desalination – Now the dominant technology • Food processing – Beverages • Cider, beer, wine. (clarification, beverage recovery) – Milk • Massive influence on the industry with many new products – Vegetable processing • Being considered for natural product recovery • Waste water treatment – Water reuse – Recovery from wastes streams Water Treatment Products Membrane Markets

MF and UF for Water treatment RO/NF membranes Desalination costs

Capital expenditure in the power industry Current Drivers and Limitations • Costs – Energy – Membrane replacement – Capital costs – Osmotic pressure

• Fouling – Avoiding fouling – Cleaning

New demands • Environmental technology – More water reuse • Decontamination of water • Metals • Organics ( endocrine conjeners, pesticides, priority pollutants – Resource recovery • Metals (Rare earth metals) • Nutrients (P, N, K) • Organic acids (fatty acids from AD systems) • Product recovery from aqueous environments – Natural product recovery • Pigments • Bioactives (Low molecular weight) peptides, amino sugars) • Flavours (Tea) – Algal biorefinary • Nutrient formulation • Harvesting • Algal component fractionation

Advances in Membrane technology • Drivers for membrane process development – New demands • Regulatory push • Resources recovery/circular economy • Waste reduction – New processes and applications • MBR • Hybrid applications – New membrane materials – Better understanding of theory • New separation strategies • Management of fouling Membrane separations and transport processes

Requires a detailed knowledge of the process environment • Membrane surfaces • Solutions properties • Complex interactions bewteen particles/ surfaces in the liquid environment Membrane reactors • MF/UF based membrane systems • Inside-out MBR.

• Outside-in MBR. – Intensified water recovery and sludge separation Membrane Bioreactors

• Basic Concept . Cell/Enzyme Separation

Spent/transformed Feed Reactor Feed

Cell Recycle Advantages ……….. and disadvantages • Initial filtration step in product recovery and water recycle • Additional costs – As cells do not interfered with recovery • Capital cost and vice-versa • Energy for pumping

• Relatively robust • Effective membrane • Physical separation with no additions management: a must • No phase change in most systems • Cleaning and regeneration need • Perfusion Reactor care

– Reduced inhibition • Operational complications – High cell concentration • Gas disengagement – High volumetric productivity • Fouling avoidance – Manipulation of the system with product formation and little growth • Gassing system possible MBR

Membrane Bioreactor Design 9

10 6

11 P P P P P 15 14 5 Sterilisation of feed 2 17 21 20 3 16 by membrane filtration 1 13 4 Inoculation from batch Feeding strategies 18 P manual control using 19 P P 8 alkali consumption as a 7 measure of activity. 12 Feed control by pump Figure.2 A diagram of membrane cell-recycle bioreactor: (1) Feed tank (100L), (2) Feed on permeate flow and membrane (Filtering area: 0.2 m2), (3) Bioreactor (26L) (4) Heat exchanger, (5) Product membrane (1 m2), (6) the alkali tank (6L, 2 N NaOH), (7) Centrifugal pump, (8) Peristaltic pump, level control (9) Nitrogen gas in and out, (10) Inoculums input, (11) Liquid level indicator/transmitter, (12) Cell Limits to operation bleed, (13) Feed tank heating/cooling, (14) Diaphragm valve, (15) Pressure gauge, (16) membrane filtration Solenoid/Pinch valve, (17) Pressure indicator/transmitter, (18) Flow meter indicator/transmitter, (19) Temperature indicator/ transmitter, (20) pH sensor, (21) Weight cell sensor. Total volume of conditions, fouling by the fluid to circulate through the system was 36L including the volumes of bioreactor and medium and cells connections. Membrane Bioreactor Membrane bioreactors: Comparative productivity. Membrane Bioreactors: enhanced product recovery & water recycle

MF/UF Cell NF/RO product Separation concentration purification

Concetrated Reactor Concentrated Feed Spent transformed Feed

Cell bleed Cell Recycle Water/medium recycle Hybrid membrane systems

• Freeze desalination RO/Freezing – Overcoming osmotic pressure limitations for water recovery

• Membrane/ stripping Ammonia stripping – Concentrates materials to facilitate stripping

• Membrane/ion exchange – Boron removal

• Combined membrane systems for refineries

Microalgae Biorefinery Options

Regional economics, demands, resources - all play a role in the best strategy and spectrum of products to be produced. Microalgae Biorefinery Options Membrane technology

Regional economics, demands, resources - all play a role in the best strategy and spectrum of products to be produced. Membrane integration • Nutrient recovery and fractionation – e.g. Fractionation of digester fluids Benefits of membrane technology Membrane technology

•Suitable technology for pre-treatment and separation •Technology quite well developed but not widely industrially applied for waste processing

Benefits of membrane filtration include:

•Physical separation (water does no change phase)

•No additives (chemicals and/or other materials) are added other than when membranes are manufactured

•There is a wide range of membrane process based on the membrane pore size

•Filtration allows manipulation of the nutrient content, when combined with leaching and acidification using MF or selective separation and concentration using subsequent NF and RO processes Advantages and commercial benefits of nutrients recovery •Reduced demand on WWTP as reduced carbon is extracted so reducing costs and energy requirements of oxidation and CO2 Algae release

•The extraction of reduced carbon (as VFA) for reuse and substitution of VFA’s derived from petrochemicals reducing reliance on fossil carbon for chemicals of favourable nutrients

•Ammonia recovery would save CO2 production Nutrient and enhance the formation of a potentially recovery valuable product if in a concentrated form

•Phosphate is a finite resource is becoming increasingly expensive (800% rise between Fig.2. Schematic diagram of advantages of the 2006 to 2008, $50 to $400) with a current value process Zacharof &Lovitt, Water Science &Technology, of over $500 per tonne Under review, 2014

Although its production is carbon neutral it’s been achieved by mining causing environmental and social issues.

Integration of AD with algal production

CO2, Heat, Power O2 Engine

Water Cell debris Fine solids Coarse Food MF MF Algae AD filtratio PBR Waste Nutrient harvesting etc. n

Dewatered Protein course solid recovery

N and P Protein Compost O2 Power minerals Feed Export Options Nutrient Recovery Methodology: Filtration

P-69

Membralox Ceramic Microfiltration (MF) membrane P-3 Pore size: 0.2μm Pressure gauge (0-4 bar)

P-6

Pressure valve

P-12 P-11

V-1

Feed Vessel

Heat Exchanger

E-4 Pressure gauge P-4 (0-4 bar)

E-2

P-5 Drain P-10 P-7 P-8 P-2 Valve E-3 V-3 Valve V-2 Regenerative Regenerative E-5 Pump E-1 Pump DiagramK eofnne t K12 RG550 Picture of the processing system the processing system Permeate composition Table 1: The influence on nutrient composition of a multi-step acidic and non-acidic DF. Both experiments 1 and 2 started with an initial filtration step (A) and are independent of each other. Experiment 1 was a two step recovery process with A1 being obtained under acidic conditions. In experiment 2 was a three step recovery process with B2 obtained through non-acidic DF and C2 through acidic DF.

Treatmen NH3-N Std Dev PO4-P Std Dev Sample N:P t mM (%) mM (%)

A (initial permeate) 48.99 7.8 1.34 15.3 36.6

1 B1 (acidic DF) 19.36 2.2 2.31 3.5 8.4 B2 (non-acidic DF) 26.00 7.0 0.83 5.6 31.5 2 C2 (acidic DF) 14.45 8.0 1.72 1.6 8.4

Nanofiltration: small molecule recovery

• The most sophisticated and powerful method for small molecule recovery

• Will require combined use of several membranes to make NF work – Tea flavour recovery – Vegetable waste processing – Potato processing – Peptide recovery Produce recovery using Integrated membrane-freeze-thaw process Heat Engine Power O2 Food Waste H2O AD or etc. Coarse Fine solids MF NF/RO Acidogenic clarified filtration clarified solution Reactor solution Low salt Freezer Dewatered Contaminated Concentrates, Ice course solid and differential crystallisation N and P Fatty acid Clean Compost minerals salts water Net energy from CHP = 405 kWh/te, Energy required to freeze 1 te water contain 2 % solids at 25oC = 119 kWh Energy required to freeze 1 te using MFT process 56 kWh assuming 50% efficiency, (i.e.15% available energy from CHP) Membranology: Spin of the University in 2013

• Membrane and fluid characterisation • Process innovation • Laboratory equipment • Consultancy • Continuing professional development

Undertaken several small projects and Innovate UK grants • Mainly with water processing and resources recovery systems Thanks very much ! Aknowledgements. – Myrto Zacherof – Michael Gerardo – Paul Williams – Darren Oatley-Radcliffe