Sludge treatment – biogas


The sludge from effluent treatment in land based fish farms originates from faeces and feed waste. Filters used for this purpose often require large volumes of flushing water, which again leads to a low dry matter content (5 – 30 grammes SS/l). To obtain effective transport and handling the sludge must be produced at the lowest possible amount of flushing water and be concentrated to a higher level of dry matter content.

Our solution step by step:
Sterner’s MAT-process  is a complete solution for sludge treatment where particles in the effluent are collected in at filter. The sludge treatment consists of gravimetric thickening, flocculatoin with polymers, dewatering and gentle drying.

Dried sludge powder of at least     90 % dry matter.

The input to the MAT process is water for filter cleaning and the output is a sludge powder of 90 % dry matter. As the dried sludge can be stored for a long period this facilitates further use and effective transport.


·         The systems we have built has proven to work fine and yield good end products

·         The MAT process works equally well on both in RAS – based fish farms as for flow-through fish farms

·         Sterner can document the performance of the effluent treatment to the government authorities

·         Sterners MAT-process is a stable and robust method which requires only a minimum of daily surveillance

·         The running costs are very low compared to other solutions

·         The process can handle large variability in water content in the flushing water from the particle filters

·         The process will be tailor made to any sludge volume and type of fish farm

·         Sterner will perform both laboratory and pilot testing of the sludge, to ensure an optimum design and good performance og the system for the individual fish farm

·         Sterner also supply filter solutions for effluent treatment, which means we may deliver a complete system if required

·         The MAT-process is based on well-proven components where the success factor has been in making the components work as a whole in the best possible manner