Turning recovered algal biomass and oyster shells into resources
Bloom Biomass Utilization
Turning by-products into value
The algal biomass recovered by Bloomo’s water treatment process, and the large volumes of oyster shell produced as a by-product of oyster farming, become high-value resources given the right equipment and assessment methods. With multi-stage conversion into aquaculture feed, soil amendments, construction materials and fertilizer feedstock, and LCA/MRV-based quantification of the carbon balance, aquatic biomass can be brought into the circular economy.
Why biomass utilisation matters now
The problem on the algal biomass side
- Profitability at industrial scale is governed by the cost of the harvesting and drying steps. Centrifugation recovers ≥90% but takes 0.8–1.2 kWh/m³, and spray drying requires ≥3 MJ/kg[1]
- A techno-economic estimate for a 1 ha industrial-scale culture in Portugal (Nannochloropsis oceanica, centrifugation and freeze-drying) puts the biomass production cost at 53.32 €/kg DW[2]. Harvesting and dewatering have also been reported to make up a large share of total cost[3]
- For feed use, how much algae can be included has been reported to differ greatly by species, so species-specific design and processing determine performance[4]
The problem on the oyster shell side
- East and Southeast Asia generate 6–8 million tonnes of mariculture waste a year. Taiwan alone accounts for about 2.2 million tonnes[5]
- The shell makes up about 70% of live weight relative to the edible portion, and disposal cost grows as farming scales up[6]
- About 95% of an oyster shell is CaCO₃[6], and its use as fine concrete aggregate and as a soil amendment has been reported[6][11], but quantitative LCA assessment by operators remains rare
A scientific caveat: oyster shells and carbon fixation
Shell calcification (Ca²⁺ + 2HCO₃⁻ → CaCO₃ + CO₂ + H₂O) also releases CO₂. One study found that, once respiration and calcification are included, shell formation in farmed bivalves is a source of CO₂ and cannot be part of carbon trading[7]; another, which built the carbon flows of calcification into an LCA, estimated a small net uptake[8]. Without long-term use (as a material lasting a century or more, for instance) and appropriate LCA boundaries, carbon fixation cannot simply be claimed. In its development work, Novelgen assesses carbon value only under LCA boundary conditions in line with ISO 14040/14044.
Novelgen’s approach
Novelgen is developing equipment that handles algal biomass and oyster shell together on site, at land-based farms, sewage treatment plants and coastal fishing ports. As the downstream stage connected to Bloomo, it makes solid–liquid separation → drying → grinding and particle sizing continuous, and is designed so that process conditions can be chosen per application.
For feed
Processing conditions that keep purity and protein content high
Biochar
Moisture management and drying designed for pyrolysis
Soil amendment
Particle size and pH adjusted for compounding with oyster shell
Beyond that, Bloomo Cloud Service continuously records throughput, energy input and CO₂ taken up, with the development goal of giving operators MRV data usable for an LCA in line with ISO 14040/14044 and for future carbon-credit calculations (applicable methodologies are under study).
Technical specifications and key figures
Every figure states its source.Research finding / Development target marks values from the academic literature and Novelgen development targets respectively.
Algal biomass processing
Algal biomass processing: details
| Metric | Value | Category | Source |
|---|---|---|---|
| Biomass concentration at PBR outlet | 0.3–0.4% DW (closed system) | Research finding | [3] |
| Solids in slurry after dewatering | 15–25% | Research finding | [3] |
| Moisture after final drying | <5% (long-term storage and transport requirement) | Research finding | [3] |
| Centrifugation energy | 0.8–1.2 kWh/m³ | Research finding | [1] |
| Spray drying energy | About 0.8–1.0 kWh/kg | Research finding | [1] |
| Algal protein content | 40–70 wt% (Chlorella 51–58%, Spirulina 60–71%, Arthrospira 70%) | Research finding | [9] |
| Theoretical CO₂ uptake (photosynthesis) | About 1.83 t CO₂ per tonne of biomass (dry weight); a stoichiometric value assuming 50% carbon, gross rather than net | Research finding | [10] |
Oyster shell as a resource
Oyster shell as a resource: details
Value streams: three recovery routes
Biomass circulation flow
Note: the biomass processing unit is in development. The flow diagram shows the design concept. Uses depend on the source water and regulations; biomass grown in sewage or industrial wastewater is not used for feed.
Aquaculture and livestock feed
Main uses
- Fine-particle feed for larval fish and bivalve seedlings
- B2B supply as a compound feed ingredient
- Feed production alongside RAS
Equipment that pellets the high-protein algae from Bloomo cultivation (40–70 wt%[9]) on site lets feed be produced where it is used (in development). Microalgae serve as a direct nutrient source at the early developmental stages of bivalves and crustaceans, and continuous supply makes density and freshness easier to manage.
Protein, ω-3 PUFA and carotenoid composition can be selected by species (Chlorella, Spirulina, Nannochloropsis and others)[4][9]. By treating aquaculture effluent with Bloomo inside the RAS and turning the resulting biomass into feed within the same facility, the design aims at circulation with no logistics in between.
Note: this indicates potential as a feed ingredient. It is not a guarantee of specific nutritional value or disease-prevention effect. For inclusion rates by species, see the literature[4]. Only algae grown in water suitable for feed production, such as aquaculture water, are used for feed. Biomass grown in sewage or industrial wastewater is not used for feed and is intended for fertilizer, biochar and similar uses. All uses are subject to analyses such as heavy metals and pathogens and to compliance with the relevant Japanese laws on feed safety and fertilizer quality.
Biomaterials (compound use with oyster shell)
Main product lines
- CaCO₃ for construction (substitute for fine concrete aggregate)
- Soil amendment (oyster shell powder + algal biochar)
- Feedstock for CO₂ mineralisation (CaO route)
Ground oyster shell has been reported to work as a partial substitute for fine concrete aggregate[6], with pre-treatment securing the particle size and purity that do not impede cement hydration. In a five-year trial on acidic red-soil upland (peanuts), applying oyster shell powder at 750–2,250 kg/ha slowed the decline in yield and curbed soil acidification and available Cd compared with no application[11]. Combining it with algal biochar as a soil amendment is a topic we are studying.
CO₂ mineralisation (the CaO route) calcines the shell into CaO and fixes flue-gas CO₂ as CaCO₃[5]. The net balance, including the energy used for calcination, needs to be assessed by LCA.
Nitrogen and phosphorus fertilizer
Main uses
- Liquid and slurry fertilizer (using the partly dewatered slurry directly)
- Solid pelleted fertilizer (compression moulding)
- Resource recovery integrated with sewage treatment
Through the nitrogen assimilation of Algal Bloom Capture, the NH₄⁺ and PO₄³⁻ in the water being treated are held in the algal biomass as protein and polyphosphate. The aim is to recover most of the nitrogen as algal protein. This should release less N₂ and N₂O to the atmosphere than nitrification–denitrification, but the nitrogen balance, including N₂O from the algae themselves[12] and ammonia volatilisation, will be confirmed in demonstration.
Note: this indicates potential as a fertilizer feedstock. It is not a guaranteed composition statement under Japan’s fertilizer law. Using wastewater-derived biomass as fertilizer requires analyses such as heavy metals and compliance with that law.
Market opportunity and positioning
3 demands
Feed, soil amendments, materials
Algal biomass market
Market figures are explained in meetings
Three sources of demand are growing in parallel: sustainability requirements in aquaculture feed (fishmeal substitution), animal-free demand for agricultural soil amendments, and low-carbon construction materials.
Fragmented → integrated
Regional GX projects expanding
Oyster shell resource market
Hiroshima, Miyagi, Okayama and others
Regional GX projects such as HIROSHIMA SANDBOX are under way. Oyster shell handling is shifting from fragmented processing to integrated processing.
GX / ESG
Decarbonisation and circularity requirements
Regulatory tailwind
Japanese policy
Japan’s GX Promotion Act and the J-Credit scheme, among others, increase the need to turn waste into resources. Whether credit methodologies exist that apply to algae or oyster shell is still being checked.
Positioning: competitive matrix
Higher value
Lower value
Integrated
Fragmented
Novelgen
Bloomo integration + LCA/MRV
All three streams at once
Existing waste handlers
Single use / cost-driven
Major chemical & feed manufacturers
High value but a single step
What sets us apart: direct connection to Bloomo cultivation / automatic recording of LCA and MRV data (in development, towards carbon valuation) / all streams handled at once.
Development and track record
Achievements so far (2023–2025)
Hiroshima Prefecture carbon recycling programme
Combined farming of Pacific oyster and microalgae
Selected for the SBIR Phase 3 fund
MAFF SME innovation promotion programme (oyster fattening system and aquatic distribution DX)
Selected for SBIR Phase 2
Recirculating aquaculture
Bloom Oyster test shipment
Start of the market supply phase
Selected for HIROSHIMA SANDBOX
Certified by the Hiroshima Industrial Promotion Organization
Currently in development
Prototype on-site dewatering and particle-sizing unit for algal biomass (downstream of Bloomo)
Oyster shell grinding × algal biochar blending unit
Bloomo Cloud Service extension linked to LCA and MRV
Milestones ahead
Standardising commercial-scale harvesting and drying equipment
Studying LCA and whether carbon-credit methodologies can apply
Confirming conformity with the relevant laws (fertilizer, feed, waste)
Note: the achievements listed are based on information already announced publicly. Equipment specifications and the development schedule may change as demonstration progresses.
References
- Geng Y., et al. "Microalgal biorefineries: a systematic review of technological trade-offs and innovation pathways." Biotechnology for Biofuels and Bioproducts, 2025, 18, 93. DOI →
- Vázquez-Romero B., Perales J.A., Pereira H., Barbosa M., Ruiz J. "Techno-economic assessment of microalgae production, harvesting and drying for food, feed, cosmetics, and agriculture." Science of the Total Environment, 2022, 837, 155742. (1 ha industrial-scale case in southern Portugal, Nannochloropsis oceanica.) DOI →
- Fasaei F. et al. "Techno-economic evaluation of microalgae harvesting and dewatering systems." Algal Research, 2018. ScienceDirect →
- Siddik M.A.B. et al. "Expanded utilisation of microalgae in global aquafeeds." Reviews in Aquaculture, 2024. DOI →
- "Sustainable conversion of oyster shell waste into high-purity calcium carbonate via CO₂ mineralization." Journal of CO₂ Utilization, 2024. ScienceDirect →
- Hong Y.-M., Choudhury S.R. "The Substitution Effect of the Fine Aggregate in Concrete with Oyster Shell." Materials, 2024, 17(24), 6148. DOI →
- Munari C., Rossetti E., Mistri M. "Shell formation in cultivated bivalves cannot be part of carbon trading systems: a study case with Mytilus galloprovincialis." Marine Environmental Research, 2013, 92, 264–267. DOI →
- Martini A., et al. "Environmental performance and shell formation-related carbon flows for mussel farming systems." Science of the Total Environment, 2022, 831, 154891. DOI →
- Ahmad A. et al. "An overview of microalgae biomass as a sustainable aquaculture feed ingredient: food security and circular economy." Bioengineered, 2022, 13(4), 9521–9547. DOI →
- Stoichiometric estimate (not a literature value): assuming carbon makes up 50% of dry weight, 0.50 × 44.01 / 12.01 ≈ 1.83 t CO₂ per t DW. This is gross photosynthetic uptake, not a net reduction; ash-rich biomass grown in wastewater can contain less carbon.
- Li H., Wu Y., Li J., Han T., Liu K., Huang S. "Long-term oyster shell powder applications increase crop yields and control soil acidity and cadmium in red soil drylands." Frontiers in Plant Science, 2025, 16, 1506733. DOI →
- Plouviez M., et al. "The biosynthesis of nitrous oxide in the green alga Chlamydomonas reinhardtii." The Plant Journal, 2017, 91(1), 45–56. DOI →
Note: figures are values for the subjects and conditions of each study, not performance values of our equipment.
Joint research and partnership
Please get in touch below about demonstration partnerships, technology licensing or joint development around the biomass utilisation equipment. Detailed materials are available following an NDA.