Usually, transferring the sludge to a tank doesn't require a high flow rate, or a large pump. As such, there are mainly four types of pumps suitable for the task.
Progressive Cavity
Progressive cavity pumps are great for sludge. They pump the wastewater with a low pulsation rate with a fixed amount that enters into the chamber. Having this benefit of cavity pumps, maintenance and repair remains a big issue. This is the reason why, the latest models of progressive cavity pumps come with innovative pumping and suction ability that makes servicing easier.
Rotary lobe pumps are known for their pumping ability when it comes to high viscosity fluids. Similar to the progressive cavity, rotary lobe has low shear and low pulsation rate. This type of pump is generally light in weight and thus, have a small footprint. Also, the wet parts are easy to get access while cleaning by just removing the cover plate in front of the pump. Due to this advantage, rotary lobes are generally expensive. But if you calculate the same for a prolonged period, the amount spent on maintenance, parts and repair is far less than a progressive cavity pump. The best rotary lobe models can be achieved from WrightFlow pumps.
AOD
AOD or air-operated diaphragm pump is a popular option for wastewater sludge. The process of this pump is very simple with just a single diaphragm powered by compressed air. The speed of the pump is also very easy to control and has a predictable fluid displacement. This type of pump produces a consistent flow to the tank that is to be filled with wasterwater sludge. Air operated diaphragm pump has a high pulsation rate as it is driven by compressed air. However, operating this pump can be a bit expensive if a large air compressor does not exists in a facility. Whenever you choose to work with this pump be sure to provide adequate compressed air to reap the actual benefits.
Select the appropriate pump based on treatment process, amount of footprint and availability of air it requires. However, if it seems to be complicating, always consult with a professional and get the best model of PDP.