ID CODE: 26951



State of the art water treatment technologies is relaying on computer systems, the AQALIFE system is managed by a purpose developed PLC

A system that can manage, track and monitor all operations.

With our new PLC system we can by the push of a bottom recreate the biological environment our shell fish comes from and thereby decrease mortalities and increase product quality says Jens Skjølstrup, technical development manager of the AQALIFE water treatment system design and partner director in Skjølstrup and Grønborg.

The systems connects to a central server through either Ethernet broadband or a GSM connection, this means that we from Denmark will be able to service the system centrally, track changes, trouble shoot and help the customers in setting the system before receiving containers or during docking. Every valve, pump, cooler, tank, sensor etc are connected with the PLC so that critical data at all times can be read and monitored on the flat screen interface.

The monitoring part is a key element in securing extreme stability of such complex water treatment facilities. Every single process is surveyed by sensors such that in case of irregular measurements the operating personnel will be informed about what actions to take.

A flow chart continuously illustrates the ongoing processes e.g. filling of tanks or water conditioning and informs about specific remaining process times and following operations. For that reason a quick glance at the control panel is enough for the operator to be informed about the system state

Alarms are divided into two levels as pre- or full alarms and are illustrated by coloured pop-up messages. Alarms are sent to the relevant persons as well as logged together with other system information.
The remote tracking of operating parameters enables our experienced engineers to, on a regular basis; monitor the performance of each docking station. Apart from documentation purposes, these data analyses are used to schedule and determine degree of service on essential system components.

The monitoring equipment is also necessary in order to obtain the very high degree of automation without compromising flexibility. The system flexibility is illustrated by the fact that each pallet tank (a 40 ft transport container holds 20) can be emptied, filled or have the water cleaned and conditioned individually. A high degree of automation means that the staff can concentrate on handling shellfish and not on system operations, an important factor in the efforts towards optimizing overall feasibility.

Water conditioning includes processes such as: Physical filtration, foam fractionation, oxygenation/degassing, Ph-stabilisation (to eliminate ammonia gas), salinity adjustment, temperature adjustment and disinfection by UVC-light.
Physical filtration is performed by screens and membranes. Screen filtration is a two-step process removing particles down to a size of app. 0.1 mm. This degree of filtration combined with foam fractionation and UVC-disinfection provides excellent water quality at destination point docking stations. Foam fractionation was chosen since our two years of experimental work revealed that a build up of nitrogenous surfactants was one of the major challenges of stocking shellfish at very high densities for prolonged periods of time. Another major problem was the build up of lethal concentrations of ammonia gas. Two actions were taken to overcome this problem. Firstly; water temperature is lowered to less than 2 °C bringing the animals into hibernation state so that a minimum of ammonia is excreted. Secondly, since it is only the unionized form of ammonia (ammonia gas, NH3) which is toxic and that this fraction is in a pH (and temperature) regulated equilibrium with the non-toxic ionized ammonium (NH4+), pH is stabilized at a value below 7 at which the fraction of protonated ammonia represents less than 1% of total ammonia nitrogen.

To achieve highest possible water quality with regard to both animal health and consumer safety water prepared for transportation of the shell fish is in addition to the previously describe conditioning also membrane filtrated. It’s a unique application of the most promising new water treatment technology developed recent years. Membrane filtration not only sterilizes the water but also removes dissolved substances down to a size of app. 250 kD. This will protect against the most commonly observed harmful chemical pollutants found in our natural waters.

During transportation from one docking station to another the shell fish water quality is secured by controlling the following key parameters: Oxygen, carbon dioxide, temperature and ammonia gas. The latter by initial pH-stabilisation as previously described. Oxygen and carbon dioxide is controlled by continuously aerating and mixing the pallet tank water and temperature by maintaining less than 2 °C in the reefer.