Integrating algal biomass production and wastewater treatment

Professor Howard Fallowfield

Health and Environment Group, School of the Environment, Flinders University, Adelaide, South

Australia

Howard.fallowfield@flinders.edu.au

Algae for wastewater treatment and added value. Can algae feed, clean and fuel the world?

RMIT University Workshop, 27th October 2015

A brief history of algal biotechnology

Glycerol & edible fat production (diatoms) Burlew Report

Energy from algal biomass; Liquid transport fuels

Energy and GHG abatement

Oswald, HRAP

Rationale for integrating wastewater treatment and

algal biomass (energy) production

Sustainable Development of Algal Biofuels in the United States (2012), National Research Council of the National

Academies

Noted: The quantity of water (whether freshwater or saline water) required for algae cultivation

– 1 L of gasoline equivalent of algal biofuel estimates suggest require 3.15 - 3,650 L of freshwater

Supply of the key nutrients for algal growth—nitrogen, phosphorus, and CO2.

– Algal biofuel @ 5% replacement of U.S. demand for transportation fuels – Equivalent to 44 -107% of the TN and – 20 - 51 % of TP current use in the United States.

Further concerns with ‘defined’ media culture of microalgae: Phosphorus

http://phosphorusfutures.net/

http://www.infomine.com/investment/metal-prices/phosphate-rock/all/

Further concerns with ‘defined’ media culture of microalgae: Nitrogen

Impact of Rising Natural Gas Prices on U.S. Ammonia Supply, United States Department of Agriculture, WRS0702 (2007)

http://www.potashcorp.com/overview/nutrients/nitrogen/overview/ammonia-cost-and-natural-gas-price-comparison

Sustainable Development of Algal Biofuels in the United States (2012), National Research Council of the National Academies

Recommendation: Sustainable development of algal biofuels would require research, development, and demonstration of the following: • The use of wastewater for cultivating algae for fuels or the

recycling of harvest water, particularly if freshwater algae are used.”

Sustainable Development of Algal Biofuels in the United States (2012), Committee on the Sustainable Development of Algal Biofuels; Board on Agriculture and Natural Resources, Division on Earth and Life Studies; Board on Energy and Environmental Systems, Division on Engineering and Physical Sciences; National Research Council of the National Academies, pp344. Prepublication Copy available at http://www.nap.edu/catalog.php?record_id=13437

Algal ponds

High rate algal ponds

High rate algal ponds (HRAP): Characteristics

• Shallow (30 – 60 cm) meandering channel design

• Mixed by simple paddlewheel • Mean surface velocity 0.2 m s-1

• Maintains solids – algal cells in suspension - maximising O2 production for treatment

• Homogenous chemical environment

• Shorter retention times for treatment (5 – 12d)

– Reduced evaporative loss – Less land area required

Richmond Calif.

Holister, Calif

HRAP Inlet wastewater composition (Kingston on Murray; anaerobically pre-treated)

Composition of septic tank treated effluent fed as influent to the HRAP

Parameter Mean ± SD Median n

BOD5 (mg L-1) 197 ± 47.7 200 48

NH4-N (mg L-1) 87.9 ± 11.7 87.8 46

NO2-N+NO3-N (mg L-1) 0.41 ± 0.64 0.31 46

PO4-P (mg L-1) 12.6 ± 3.3 12.5 44

Suspended solids (mg L-1) 107.3 ± 37.5 101 48

log10 E. coli 100ml-1 6.347 ± 0.374 6.398 48

Conductivity (µS cm-1) 1169 ± 182 1181 12

Simplified process cycle

South Australia: Domestic Wastewaters

Study site

Kingston on Murray Flinders University 500 km return

Kingston on Murray Project South Australia

(Nancy Cromar, Neil Buchanan, Paul Young)

Kingston on Murray

36 d; 1.2m

7.5 d

Reuse

South Australia: Community Waste Management Schemes (CWMS)

Normally 3,000L; 24h detention, 60-70% SS & 30% BOD5 removed

5 cell - Waste stabilisation ponds

Kingston on Murray HRAP: Overview Township • Population 150 – 300 • Effluent treated 12 m3 /d Climate • Irradiance 8.3 MJm-2 (June – winter) to 28.1 MJm-2 (January –

summer) • 3.8°C minimum July to 31.8°C maximum in January, HRAP • Surface area 200m2

• Operated at 0.32 – 0.55m depth • THRT 5d • Mixing 0.2m/s

Albazod & Algal Productivity (g/m2/d) mean ±standard deviations & ranges

Albazod

Productivity

(g/m2/d)

Algal

Productivity

(g/m2/d)

Mean ± sd

(Range)

Mean ± sd

(Range) Deep-Cold 6.4±5.0

(1.52-13.9) 3.37± 2.92 (0.92-8.35)

Shallow-Hot 49.5±33.9 (12-113)

25.31±17.71 (7.17-60.9)

Annual - All depths

34.5±34.4 (0.9-127)

20.7±20.6 (0.55-76.3)

Net daily biomass energy production

Kingston on Murray HRAP wastewater treatment performance

(n=120)

Inlet (pre-treated in septic tanks)

% Removal

BOD5 (mg/L) 204 92.3

NH4-N (mg/L) 89.9 69.1

TN (mg/L) 91.2 53.5

PO4-P (mg/L) 15.6 16.4

E.coli (MPN/100ml) 6.36 1.74*

*log10 reduction value

Outcomes HRAP system treatment: • in 4 - 8 days compared with 66 days required by the 5 cell lagoon system

• using 40 – 50% less surface area

• with only 11- 30% of the earthworks of CWMS lagoon system

• construction cost of the HRAP system 40 – 55% that of a conventional

lagoon system • reduces evaporative loss of the treated wastewater (12 – 17%) compared

with 30% for the conventional CWMS; resulting in more water being available for beneficial reuse in rural communities.

• Will be approved by the SA Department of Health as an alternative pond system for application in rural communities

Melbourne Water Corporation & Smart Water Fund

Melbourne

Algae for Energy and Wastewater Treatment

Project 8OS-8085

(Michael Taylor, Neil Buchanan)

Research objectives • Determine

– biomass productivity – species – proximate composition

• Determine wastewater treatment

potential – BOD5, nutrient removal – E.coli removal l

• Provide data for LCA

Covered anaerobic lagoon

AGL Power station

HRAPs

HRAP Influent

Raw wastewater influent

Study design

• Effect of the addition of CO2 to wastewater on algal productivity and wastewater treatment.

• Depth – retention time study.

• Longitudinal data set – algal productivity and wastewater treatment.

(1) Effect of CO2 Addition

Wastewater

AGL gas scrubbers, removal of H2S & CO2

North high rate algal pond, inflow enriched with CO2

South high rate algal pond, inflow ‘native’ wastewater

Effect of CO2 Addition

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

50.0

Prod

uctiv

ity (g

DM

/m2/

day)

Month

North Pond

South Pond

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Mea

n %

sol

uble

tota

l nitr

ogen

rem

oval

North pond South pond

(2) Depth – retention time study

Seasonality

Composition of inlet wastewater N Minimum Maximum Mean Std. Deviation

Suspended solids (mg/L) 49 10 350 53.7 66

Total organic carbon (mg/L) 98 3.59 140.7 19.6 19.1

Total Nitrogen (mg/L) 98 29 88.8 73.6 9.4

Ammonia (mg NH4-N/L) 49 <1 114.3 64.5 29.2

Sum Nitrate/Nitrite (mg NOx-N/L) 49 .02 20.9 5.4 6.1

Soluble Phosphorus (mg/L) 49 3.9 22.4 11.2 4.4

Particulate organic carbon (POC; mg/L)

49 .39 99.3 16.9 17.5

Particulate organic nitrogen (PON; mg/L)

98 <1 18.4 5 4.2

Depth – retention time

(3) Longitudinal study

Intensive livestock wastewaters: Pig slurries

Experience in wastewater treatment using microalgae - UK

Piggery wastewater • Northern Ireland

– Screened pig slurry – 1:9 diluted to enable growth – THRT 4.4d, depth 0.2m – Productivity 18.1 g DM m-2 d-1

• West of Scotland

– Aerobically pre-treated – 11m2, 0.2m, diluted 1:4 – Productivity 18.3 g DM m-2 d-1

• Ammonia toxicity and light attenuation significant problems

Fallowfield, H.J. & Garrett, M.K. (1985) An energy budget for algal culture on animal slurry in temperate climatic conditions . In Energy from Biomass (Eds. Palz, W., Coombs, J. & Hall, D.O.) Applied Science Publishers.

Co-operative Research Centre for High Integrity Australian Pork (Pork CRC)

– Reduce GHG emissions from 8kg CO2–

e / kg pork to 1 kg CO2–e / kg

– 83% pork producers use ponds to treat wastewater

– LCA, GHG emissions reduced by: • covering anaerobic lagoons;

recovering CH4

• Incorporating further algal treatment for:

– Biomass energy – CH4 – High quality reuse water

Piggery wastewaters : Australia

Acknowledgements

Ken Baxter, Gwyneth Elsum, Wade Mosse, Justin Lewis, Tom Murch Members of the PAC

Richard Gayler

Roger Campbell Graeme Crook

Ashraf Abdelmoteleb Ray Komatsu, Jessica Yeung, Damien Connell

Neil Buchanan (30th Dec 1954 – 2nd July 2015)