Integrating algal biomass production and wastewater treatment
Professor Howard Fallowfield
Health and Environment Group, School of the Environment, Flinders University, Adelaide, South
Australia
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)