Status of the project

BiFFiO has been granted a 3-month extension and the project period ended on January 31 2017, with all scheduled scenarios successfully completed. Collected data have been evaluated and analyses regarding nutrient recovery, heavy metals, biogas gas yield and quality and other parameters of the different mixes of the substrate have been performed.

Growth trials

Extensive growth trials have been carried out using large pot experiments with different plant species. For trials involving marine aquaculture waste, salt tolerant species widely used on coastal golf courses have been used. The main goal of the plant growth trials was to assess the potential of direct application of the liquid digestate to target species and evaluate the impact on growth. In addition, the trials were used to measure the extent to which the digestate acted as fertiliser. The composition of the digestate from the CSTR AD reactors is thus mainly liquid (90%). The nutrient balance in the digestate from the different ratios of mixes of aquaculture and agriculture waste has been evaluated using regression analysis.

Functionality tests of liquid-solid separation with electroflocculation

Based on evaluation of SOA liquid-solid separation methods of digestate, a prototype of elctroflloculation unit has been built and subjected to functionality tests. Results showed good rate of separation when key optimum parameter values of the electroflocculation cell are applied.

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The separation process stops after 4 hours due to need of electrode cleaning.

Assessments of the collected data from the functionality trials of the BiFFiO best practice revealed the following findings:

  • Fresh water aquaculture sludge seems to be very suitable for AD especially in combination with cuttings
  • Marine aquaculture sludge show less biogas potential
  • CSTR-technology is simple and robust and fulfils the needs of the farmers (fish and cattle)
  • Nutrient value and content of the digestate is strongly dependent on the feedstock
  • The available nitrogen in freshwater waste is proportional to the total nitrogen whereas, the available nitrogen in marine waste declines with increasing sodium content
  • Marine slurries have a suppressing effect on germination and growth at higher concentrations
  • Micronutrient content of marine slurries is warrants further investigation.
  • Electroflocculation is a promising technology for liquid-solid separation of digestate.

Joint symposium of BiFFiO with a Norwegian project

In connection with training of the Nobio members, a joint symposium between BiFFiO and a project run by Norwegian Institute of Bioeconmy Research (NIBIO) was organised on January 31 2017 with participants from BiFFiO (7 persons) and membership of Nobio from different corners of Norway, including NIBIO. The NIBIO project has been run with almost similar methodology, and the attained results of the two projects are also very similar. Therefore, it has been suggested to initiate a joint follow up project for utilising the attained results.

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