Modelling sustainable use of process streams in ragworm culture

In the Province of Zeeland ragworms (Alitta  virens) are farmed on large scale (6 ha) in open rectangular (flow through systems) ponds. Every April these ponds are stocked with ragworm larvae from a hatchery. The juveniles bury themselves in the sediment layer in the pond and are fed with feed pellets. Dependent on the market (bait for fishing or maturation feed for shrimp farming) market size ragworms are harvested after 7 – 20 months.

The process water produced by ragworm farming has great potential for growing micro-algae and subsequently bivalves. However, little is known about the composition in terms of dissolved nutrients and particles of the waste streams, under different conditions (density of ragworms, seasonal variations, amount and type of feeding, etc.).

In the past year, laboratory and field settings experiments were conducted to investigate the nutrient balance and possibilities to culture microalgae Skeletonema costatum on ragworm waste water. Several measurements on the composition in terms of dissolved nutrients and particles of the waste streams, under different conditions (density of ragworms, seasonal variations, amount and type of feeding, etc.) have been carried out.

To get a better insight in the implication of the use of ragworm waste water for algae production on a large scale, a production model might be a  useful tool. In the model, the gathered data of the experiments and field situation, together with other available data are combined. Production of algae is coupled with the composition of process water  and the dependency on seasonality, feeding rate, density, etc. The goal of the production model is to run different scenarios and evaluate the feasibility of different setups of the large scale coupling of rag worm process water and micro algae production.

Research type: literature study, experiments (ragworm farm location ) and design a model.

Research level: final thesis (BSc./MSc. level)

Prerequisite: good understanding of biology/chemistry; good analytical and Excel skills; communicative; computer skills

Partners: several Small and Medium (Aquaculture) Enterprises, Flemish  knowledge partners, Province of Zeeland

Researcher involved: research group aquaculture (Michel Trommelen and Jouke Heringa)

Period: 2nd semester 2017-2018

Status: Open