Frequently Asked Questions

The majority of our items are engineered and fabricated specifically to fit your project. Depending on your requirement, the price range can vary dramatically, see the below table for rough estimates.

This is a by-product of industrial or commercial activities across all industries. Every step in the commercial process (regardless of industry) results in wastewater which must be carefully managed for safety, environmental and sustainability reasons. These can include hazardous chemicals or materials that require decontamination.

Sludge is a term used to describe thick, soft, wet mud or similar viscous mixture of liquid and solid components. It is a by-product associated with the industrial or refining process and may contain many undesirable or hazardous substances.

There are two main types of sludge produced from Wastewater treatment. Primary sludge is generated from chemical precipitation, sedimentation or other primary processes. Secondary sludge results from a process using microorganisms to consume the organic matter in wastewater (e.g. Anaerobic ponds) which results in a settling of biomass to be removed as sludge.

Sludge has to be properly treated and disposed of to prevent environmental contamination and health risks.

Slurry is defined as a semi-liquid mixture, typically of fine insoluble particles, which are suspended in water. Slurries can be broken down into type types, settling and non-settling (based on the solid materials represented in the mixture).

From a designer’s perspective, it is important to know the type of slurry. For example, non-settling slurries can be transported around under laminar flow conditions, whereas turbulent flow conditions are required for settling slurries, particularly in horizontal sections.

Controlling the depth of the pump on the Dredge series is via a remote controlled 12V winch. The operator can safely trim the pump up or down to make sure that the suction head of the Dredge is at all times in the sludge and not just drawing water. It is recommended that profiles of the pond are obtained prior to commencement of operations. This will allow
a more informed plan of operations to formulate. The hand held remote transmitter used to control the 12V depth winch on the Dredge series.

When pumping and winching it is important to keep a very close eye on the Unit and the 415V land based winch, particularly on the first two or three runs across the pond. This is when you will get a feel for the profile and undulations of the sludge in the pond. It is important that while winching the Suction Dredge, in particular, the suction head is not buried too deep into the sludge. Approx. 200 – 300 mm into the sludge/sediment on each pass is sufficient. This distance may vary depending on the thickness of the material to be removed. If the suction head is too far into the sludge it can cause blockages, over tension on the winch rope and damage to equipment.

Pump blockages may sometimes occur. The first step is to identify the blockage. The test junction at the side of the pond is the best indication if there is a problem. By allowing a small amount of water/sludge to flow back into the pond via the test junction, gives you an instant visual on whether or not there is flow passing through the discharge
hose. Periodically open the test junction to check if the flow rate is good. You may then close the junction and allow it to run.

If you detect that the material which is being pumped is too thick for the pump to push along the discharge hose. Raise the pump on the machine and/or slow the speed of the land based 415V winch. This allows a better blend of surface water and sludge, bringing the percentage of solids to a pumpable consistency.

Other causes of a pump blockage:
▪ Kinked hoses may need to be straightened
▪ A leak in the hose prior to the discharge point
▪ A blockage in the hose such as a stick, plastic bag or even a cup
▪ A blockage in the pump intake or discharge flange

It is the operator’s job to maintain consistent sludge during pumping operations. This is achieved by adjusting the depth of the suction head [Trimming]. It is also important to get the speed of the land based winch correct. Some heavily compacted materials need more time to loosen as the Dredges move through it, hence a slower speed of travel is necessary. The speed is adjusted via the variable speed drive [VSD].

Not only is it important to maintain consistent sludge, but a consistent flow rate should also be maintained. Flow rates will depend on sludge % solid, the size of the pump, the speed of the winch, the distance the material has to be pumped, frictional loss and head.

It is important to take all these factors into consideration. No.1 is to have the right pump for the task at hand. Once the pump selection has been made correct operations procedures can be implemented. Flow rate is now in the hands of the operator. The aim is to maximise the percentage of solids being pumped without greatly affecting the flow of discharge.

If you experience a poor sludge consistency, but a good flow rate, this can be due to the following:
1. Suction head is too far away from the sludge to be pumped, and needs to be lowered.
2. The speed of the land based 415V winch needs to be sped up.
3. The sludge to be removed is very heavily compacted.
4. The majority of the sludge has already been removed and the system needs to be run on a different path.

More is coming here shortly.

More is coming here shortly.