Discussion on the use of membrane grids

Compared to traditional grating grids, membrane grids use defined two-dimensional square-hole filters to ensure effective solid-liquid separation. The two-dimensional separation design and the very small square openings allow fibrous materials and hair to be trapped within the grid basket. Traditional grating grids, due to their one-dimensional design, cannot define separation gaps, and thus cannot achieve such a separation effect. At the same time. Square-hole filter screens have a large filtering surface area, allowing them to handle higher hydraulic loads. Membrane grids are suitable for municipal and industrial wastewater treatment, with a maximum treatment capacity of 3500 m3/h; the square pore size ranges from 0.5 to 1.0 mm. The ROTAMAT® membrane grid system is highly compact, occupies little space, and features high treatment efficiency. It integrates functions such as sludge filtration, transfer, pressing for dewatering, and discharge, making it an economical and efficient grid device for treating wastewater with high solid content.

➤➤➤Working principle: The membrane grid is installed at an inclined angle; wastewater flows into the grid basket through the openings on its end faces, and hair and fibers in the water are trapped by the finely spaced grid. A specially designed seal is installed between the opening at the end face of the grid basket and the channel, to ensure that wastewater does not flow backward without being filtered. When a certain water level difference is achieved between the water levels in front of and behind the grid, the device activates; it lifts the slag from the grid through the rotation of the grid basket, and uses flushing rods to push the slag into the central chute. There is a transport screw inside the central chute to discharge water into the channel. The entire process is clean and odorless. Reused water can also be used as the rinsing water for cleaning the grid baskets. In addition to medium-pressure flushing, the device is equipped with timed high-pressure flushing (usually twice a day) to ensure thorough removal of deposits from the grid baskets.

The filtration and separation of hair and fiber substances prior to the membrane bioreactor depend on the size of the pores determined by the membrane system. Membrane modules are divided into two types: hollow fiber and plate membranes. Hollow fiber membrane systems have high requirements for pre-filtration, and it is crucial to remove fibrous substances from wastewater, as these fibers can entangle and clog the membrane filtration system, thereby reducing the membrane’s permeability and the efficiency of treatment. Therefore, for hollow fiber membrane treatment equipment, the pore size of the filter pores should be as small as possible.

Reduction of COD/BOD5 at river and sea outfalls: It is very important to remove the oxygen-consuming load from water as much as possible before discharging it into receiving water bodies. Most river and sea outfalls lack mechanical filtration treatment. Installing membrane grids with a mesh spacing of 0.5 to 1.0 mm at the river and sea outfalls can be very effective in reducing COD/BOD. In this application, it is not necessary to clean the slag in order to recover the carbon source as much as possible. Industrial wastewater treatment: New environmental regulations pay special attention to the way wastewater enters the sewage networks. Therefore, mechanical pre-treatment is required at the wastewater source, and the filter residue must be treated. ROTAMAT® membrane grids combine slag separation, transfer, and dewatering in one unit, occupying a small space, making it particularly suitable for this purpose.