Aquaculture – Sludge Treatment

Norlex Systems offers innovative customised solutions within sludge treatment and complete systems for heavy metal removal, without the use of chemical polymers and the ability to turn sludge into a valuable resource.

Custom solutions within Sludge Treatment designed for easy installation

Norlex Systems product range offers customised turnkey solutions for treatment of sludge from aquaculture regardless of species.

Our energy optimized solutions for sludge treatment have the following advantages:


Removal of heavy metals such as zinc and cadmium


Potential polymer free


Limited footprint


Reuse of treated wastewater


Can meet any requirements to the effluent from the sludge


Sludge from aquaculture is a potential fertilizer, however it cannot be used directly as fertilizer due to the content of heavy metals and chemical polymers and is generally regarded as a waste product. Norlex Systems offers unique sludge treatment solutions without the use of chemical polymers, by removing heavy metals and without creating hazardous by-products turning sludge into a valuable resource.

Removal of heavy metals

Sludge from aquaculture is classified as quality class 1 due to the content of zinc and cadmium. Our innovative solutions offer the ability to remove the heavy metals from the sludge. This advanced process turns the sludge from quality class 1 into quality class 0, which allows the sludge to be used as fertilizer with limited restrictions compared to sludge classified as quality class 1.

Polymer free sludge treatment

Norlex Systems offers unique solutions which combine power ultrasound and electrolysis, dewatering and without introducing polymer (chemical flocculants) into the process at any stage. This innovative process removes particles, phosphates, organics, ammonia and particulates from the sludge and produce a polymer free effluent which is ideal for recycling and reuse in the fish tanks.

Customized solutions within sludge treatment

Norlex Systems offers various customized solutions within sludge treatment. The solutions listed below are not standard solutions, but examples of some of the different possibilities we offer. At Norlex Systems each sludge treatment solution is designed, engineered and combined according to any given customer requirements.

Flocculants – Gravity belt filter – Decanter

It is essential to use a flocculant on gravity belt. The flocculant will accelerate the drainage of water and allow it to flow through the sludge and the filtration belt. The flocculated sludge flows over a filtration belt that is conveyed at a certain speed. The water freed by the flocculation step is drained through the pores of the belt. This elimination of water leads to a thickening of the sludge at the end of the conveyer belt. Nozzle sprays cleans the pore of the belt to prevent plugging.

The filtrate is returned to the beginning of the process while the thickened sludge is sent to a temporary storage tank before it is pumped to the decanter for further dewatering.

Electrolysis – Ultrasound – Separator – Decanter – Drying

The flocculation process of the sludge is a combined process of electrolysis and power ultrasound. The flocculated sludge flows to the separator, which removes the flocs, before the dewatered sludge is pumped into the decanter. From the decanter the semi-dried sludge is let through a drying unit as final stage of the sludge treatment.

Flocculants – Drum dewatering unit

The principle is identical to the gravity belt. Sludge conditioning with a flocculant, liberation of interstitial water in the sludge, gravity drainage of the free water through a grid of the drum dewater unit. A drum dewatering unit is preferred when the requirement to the dry matter content is higher than the belt filter.


BioChar and Lexinite are unique options, which each can be added to any systems within our range of innovative sludge treatment solutions.


BioChar is produced in a patented pyrolysis process. The product in form of biochar is stable, odourless and rich in recirculated phosphorus. The biochar can be used as fertilizer and for soil improvement.

Lexinite solution

Lexinite reduces the amount of heavy metals in liquids and sludge. The goal is to bind the heavy metals in the Lexinite filter, to de-classify the sludge. The sludge can thereby be used directly as a fertilizer, even when it is concentrated. The heavy metals are bound in the Lexinite and can be disposed of as inert waste.

Norlex Systems Sludge system has been successfully installed at fish farms where it effectively removes the contaminants from the waste stream, producing clean, recyclable water and a contaminant-free sludge which can then be further processed to form a dry material that is easy to handle and store, allowing the owners to turn contaminated fish sludge into a usable fertilizer, and so turning an expensive waste product into a valuable commodity.

Besides the innovative sludge solutions, Norlex Systems also offers other technologies as IntenseOx with ozone, and state-of-art chemical

Contact us and learn more about what we can offer

Norlex Systems has strong competences and products - if you need start treating your wastewater, you want to optimise an existing process or expand its capacity, or you require new water purification technology. Call us +454594 0994 or send an email to