Paper Title
UTILIZATION OF WASTEWATER TOGETHER WITH FISH PROCESSING RESIDUES FOR HETEROTROPHIC AND MIXOTROPHIC GROWTH OF GALDIERIASULPURARIA

Abstract
The present study is a part of CLIMAQUA project aims at recirculation and zero-waste re-utilization of aquaculture and fish processing side-streams (sludge after enzymatic hydrolysis of rainbow trout and wastewater obtained from fish processing facility of Hofseth AS) in cultivation of algae (Galdieriasulpuraria) for further feed production for aquaculture. The main objective of CLIMAQUA project was to develop a flexible system for the production of Galdieriasulpuraria biomass that can be used in a decentralized manner in the areas of aquaculture, thus contributing to regional development and the reduction of greenhouse gases. In conventional aquaculture, feed production is responsible for 50% of greenhouse gas (GHG) emission. The aim was to substantially reduce GHG emission by considering geographic and site-specific characteristics (temperature, sunshine duration, etc.) and to design site-specific phototrophic or heterotrophic cultivations for development of highly digestible feed ingredients for aquaculture. For the laboratory trials of cultivation of Galdieriasulpurariabiomass, 6 kg of sediments after enzymatic hydrolysis of rainbow trout at Norwegian University of Science and Technology (NTNU), along with 1 kg of fish sludge and 10 kg of wastewater obtained from Hofseth AS (Ålesund, Norway), were used at Institute for Food and Environmental Research (Germany). Before the trials, all products were physico-chemically characterized at NTNU. So far, the results have shown that fish sludge has a potential to be used as a substrate for the algae cultivation. However, more investigation is needed to establish the conditions for re-utilization of sludge and wastewater for the efficient cultivation of Galdieriasulpuraria. Norway has established efficient aquaculture food production systems and will work on methods for better utilisation of fish processing side-streams. This cooperation will strengthen regional capabilities and contribute to food security and resource utilisation efficiency under climate change expected within 1.5 or 2°C until 2050. Keywords - wastewater, microalgae, sludge, aquaculture, reutilization