DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Co-digestion of Wastewater-Grown Filamentous Algae With Sewage Sludge Improves Biomethane Production and Energy Balance Compared to Thermal, Chemical, or Thermochemical Pretreatments

Journal Article · · Frontiers in Energy Research
ORCiD logo [1];  [2];  [3];  [2];  [2];  [2];  [4]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  2. Columbus State University, Columbus, GA (United States)
  3. Univ. of Texas, San Antonio, TX (United States)
  4. Vernadsky Crimean Federal University, Simferopol (Republic of Crimea); Water Technologies Research and Production Company, Simferopol (Republic of Crimea); Water of the Crimea State Unitary Enterprise of the Republic of Crimea, Simferopol (Republic of Crimea)

Wastewater algal treatment systems show improved economic viability and enhanced energy return on investment when the algal biomass is converted to biofuel. One biofuel option is to anaerobically digest the algae to generate bio-methane. This method is appropriate for filamentous algae that are typical of turf scrubbers®, because they have relatively low lipid content. But unbalanced carbon to nitrogen (C/N) ratio and the resistance of algal biomass to biodegradation can limit it conversion into bio-methane. To evaluate options to improve algal derived bio-methane production, an indigenous assembly of macro-algae was established and cultivated in CO2-infused secondary wastewater effluent, then harvested and either anaerobically digested using pretreatments or co-digested with sewage sludge. Results were used to develop methane production kinetic models and perform an AD system energy balance analysis in order to evaluate the feasibility of pretreatment and co-digestion for a scaled process. Dominated by Ulothrix and Oedogonium periphyton biomass production rates averaged 3.7±0.4 g VS m-2 d-1 (±1SD) and increased by 62 % in the second half of the 14 day cultivation experiment. Ultimate methane yield from harvested biomass (306±13 mL gVS-1) was improved through thermal pretreatment by 15%, dilute acid by 5%, dilute alkali by 17%, acid- and alkali-assisted thermochemical pretreatments by 23 and 27%, respectively. However, all pretreatment methods had negative impact on energy balance parameters except alkali-assisted thermochemical pretreatment, which provided only a minor positive effect. In contrast, co-digestion of algal biomass with sewage sludge enhanced methane yield and reached maximum value of 401±3 mL gVS-1 at algae to sludge ratio of 20% to 80%. Most importantly, co-digestion strongly improved AD system energy balance. Net Energy Ratio and Net Energy Efficiency increased from 2.8 and 73% for algae as sole substrate to 4.3 and 81%, respectively, for an algae to sludge ratio of 20%:80%. Moreover, the Net Energy Recovery during co-digestion reached 39% compared to only 26% and 33% when algae or sewage sludge were processed as single-substrates. Thus, co-digestion of algae with sewage sludge serves as an attractive option for extracting bioenergy from biomass harvested from filamentous algal polyculture treatment systems.

Research Organization:
Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
Sponsoring Organization:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Office of Sustainable Transportation and Fuels. Bioenergy Technologies Office (BETO)
Grant/Contract Number:
AC05-76RL01830
OSTI ID:
1525900
Alternate ID(s):
OSTI ID: 1529546
Report Number(s):
PNNL-SA-139910
Journal Information:
Frontiers in Energy Research, Vol. 7; ISSN 2296-598X
Publisher:
Frontiers Research FoundationCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 23 works
Citation information provided by
Web of Science

References (67)

Algal Turf Scrubbing: Cleaning Surface Waters with Solar Energy while Producing a Biofuel journal June 2011
A Rapid Method of Total Lipid Extraction and Purification journal January 1959
The effects of alternative pretreatment strategies on anaerobic digestion and methane production from different algal strains journal March 2014
Phytoremediation of agriculture runoff by filamentous algae poly-culture for biomethane production, and nutrient recovery for secondary cultivation of lipid generating microalgae journal December 2016
Anaerobic digestion of lipid-extracted Auxenochlorella protothecoides biomass for methane generation and nutrient recovery journal May 2015
Effects of inoculum size, light intensity, and dose of anaerobic digestion centrate on growth and productivity of Chlorella and Scenedesmus microalgae and their poly-culture in primary and secondary wastewater journal November 2016
Bioprospecting of microalgae for integrated biomass production and phytoremediation of unsterilized wastewater and anaerobic digestion centrate journal May 2015
Synergistic co-digestion of wastewater grown algae-bacteria polyculture biomass and cellulose to optimize carbon-to-nitrogen ratio and application of kinetic models to predict anaerobic digestion energy balance journal December 2018
Production of lipid-containing algal-bacterial polyculture in wastewater and biomethanation of lipid extracted residues: Enhancing methane yield through hydrothermal pretreatment and relieving solvent toxicity through co-digestion journal February 2019
Bioenergy from wastewater resources: Nutrient removal, productivity and settleability of indigenous algal-bacteria polyculture, and effect of biomass composition variability on methane production kinetics and anaerobic digestion energy balance journal December 2018
Impacts of thermal pre-treatments on the semi-continuous anaerobic digestion of waste activated sludge journal April 2007
Mechanism of Methane Fermentation journal March 1952
Carbon-to-nitrogen and substrate-to-inoculum ratio adjustments can improve co-digestion performance of microalgal biomass obtained from domestic wastewater treatment journal November 2017
Contribution of Wastewater Treatment Plant Effluents to Nutrient Dynamics in Aquatic Systems: A Review journal May 2009
Phosphorus removal from wastewater using an algal turf scrubber journal March 1996
A controlled stream mesocosm for tertiary treatment of sewage journal May 1996
Anaerobic digestion of straw and corn stover: The effect of biological process optimization and pre-treatment on total bio-methane yield and energy performance journal December 2016
Eutrophication of U.S. Freshwaters: Analysis of Potential Economic Damages journal January 2009
Influence of different pre-treatment routes on the anaerobic digestion of a filamentous algae journal February 2013
The use of thermochemical and biological pretreatments to enhance organic matter hydrolysis and solubilization from organic fraction of municipal solid waste (OFMSW) journal March 2011
Taxonomic, Phylogenetic, and Ecological Diversity of Methanogenic Archaea journal August 2000
Microalgae recycling improves biomass recovery from wastewater treatment high rate algal ponds journal December 2016
Methane production from marine, green macro-algae journal January 1983
Eutrophication and harmful algal blooms: A scientific consensus journal December 2008
The effects of substrate composition, quantity, and diversity on microbial activity journal May 2010
Dynamic Transition of a Methanogenic Population in Response to the Concentration of Volatile Fatty Acids in a Thermophilic Anaerobic Digester journal February 2006
Treatment of swine manure effluent using freshwater algae: Production, nutrient recovery, and elemental composition of algal biomass at four effluent loading rates journal February 2006
Dewatering as a non-toxic control of nuisance midge larvae in algal wastewater treatment floways journal November 2014
Influence of temperature and pretreatments on the anaerobic digestion of wastewater grown microalgae in a laboratory-scale accumulating-volume reactor journal June 2014
Ultrasound pretreatment of filamentous algal biomass for enhanced biogas production journal June 2014
Phosphorus removal using nanofiltration membranes journal July 2011
Substrate Type and Free Ammonia Determine Bacterial Community Structure in Full-Scale Mesophilic Anaerobic Digesters Treating Cattle or Swine Manure journal November 2015
Comparison of seven types of thermo-chemical pretreatments on the structural features and anaerobic digestion of sunflower stalks journal September 2012
Treatment of dairy manure effluent using freshwater algae: Algal productivity and recovery of manure nutrients using pilot-scale algal turf scrubbers journal November 2008
A modified single solution method for the determination of phosphate in natural waters journal January 1962
Electric Energy Consumption of the Full Scale Research Biogas Plant “Unterer Lindenhof”: Results of Longterm and Full Detail Measurements journal December 2012
Alkaline thermal sludge hydrolysis journal February 2003
Bioassay for monitoring biochemical methane potential and anaerobic toxicity journal January 1979
Wastewater treatment and algal production in high rate algal ponds with carbon dioxide addition journal February 2010
Wastewater treatment high rate algal ponds for biofuel production journal January 2011
Evaluation of methane production and macronutrient degradation in the anaerobic co-digestion of algae biomass residue and lipid waste journal May 2012
Comparing pretreatment methods for improving microalgae anaerobic digestion: Thermal, hydrothermal, microwave and ultrasound journal November 2015
Long-term anaerobic digestion of microalgae grown in HRAP for wastewater treatment. Effect of microwave pretreatment journal February 2014
Biogas production from microalgae grown in wastewater: Effect of microwave pretreatment journal August 2013
Updated world map of the Köppen-Geiger climate classification journal January 2007
Phycoremediation coupled production of algal biomass, harvesting and anaerobic digestion: Possibilities and challenges journal December 2013
Relationship between microbial activity and microbial community structure in six full-scale anaerobic digesters journal December 2012
Influence of mechanical and thermochemical pretreatments on anaerobic digestion ofSpirulina maxima algal biomass journal October 1983
Municipal wastewater sludge as a sustainable bioresource in the United States journal July 2017
The effect of thermal pretreatment on the anaerobic biodegradability and toxicity of waste activated sludge journal January 1984
Increased pond depth improves algal productivity and nutrient removal in wastewater treatment high rate algal ponds journal April 2014
Microalgae as a Feedstock for Biofuel Precursors and Value-Added Products: Green Fuels and Golden Opportunities journal November 2015
Selective electrode measurement of ammonia in water and wastes journal June 1973
Investigation of anaerobic digestion of Chlorella sp. and Micractinium sp. grown in high-nitrogen wastewater and their co-digestion with waste activated sludge journal September 2015
Hydrolysis of macromolecular components of primary and secondary wastewater sludge by thermal hydrolytic pretreatment journal October 2009
Energy use and energy intensity of the U.S. chemical industry report April 2000
Anaerobic co-digestion of algal sludge and waste paper to produce methane journal January 2007
Microalgal biomass production pathways: evaluation of life cycle environmental impacts journal January 2013
The techno-economic potential of renewable energy through the anaerobic digestion of microalgae journal January 2011
Enhancement of methane production from Cotton Stalk using different pretreatment techniques journal February 2018
Operation of a vertical algal biofilm enhanced raceway pond for nutrient removal and microalgae-based byproducts production under different wastewater loadings journal April 2018
Cultivation of algal biofilm using different lignocellulosic materials as carriers journal May 2017
Vertical-algal-biofilm enhanced raceway pond for cost-effective wastewater treatment and value-added products production journal August 2018
Inhibition Effect of Sodium Concentrations on the Anaerobic Digestion Performance of Sargassum Species journal June 2017
Anaerobic co-digestion on improving methane production from mixed microalgae ( Scenedesmus sp., Chlorella sp .) and food waste: Kinetic modeling and synergistic impact evaluation journal September 2016
Effects of Methanogenic Inhibitors on Methane Production and Abundances of Methanogens and Cellulolytic Bacteria in In Vitro Ruminal Cultures journal February 2011
Microbial community structure and dynamics during anaerobic digestion of various agricultural waste materials journal April 2013