MICROSTRAINERS (VERY FINE MESH SCREENING)
Microstraining is a very fine mesh screening system used for the following applications. Mesh apertures from 20 microns to 220 microns are available.
As preliminary treatment of drinking water drawn from lakes, reservoirs and rivers.
A complete treatment of water for industrial purposes.
Tertiary treatment of sewage water.
A means of recovering valuable fine particles or plankton from effluent water.
HOW IT WORKS
The BEAUDREY microstrainer is a horizontal, motor-driven drum screen covered in very fine mesh. It rotates between two wall-plates. The water enters the drum, flows through the mesh on which the particles are arrested. The drum rotates and the particle-laden mesh travels upwards out of the water. On reaching the top, it is back-washed by 1 or 2 low-pressure spray pipes with fantail jet nozzles.
The particles and wash fall into an internal collection trough and exit axially for disposal. The sliding seal between the rotation drum and the end plates is specially designed to offer no gap larger than the mesh aperture.
It operates best at a constant level of head-loss (approximately 100 mm). For this to happen, the drum’s rotation velocity is constantly adjusted.
Sizing is based on the flow rate and the clogging capacity of the water (as measured by the BEAUDREY PC** for instance). The smaller the mesh aperture, the larger the machine required.
** PC = Pouvoir Colmatant or clogging factor
The graph shown below is self-explanatory.
For the same flow rate, a microstrainer sized for a 20 micron aperture must be twice wider than a microstrainer required for a 35 micron mesh aperture.
BEAUDREY microstrainers are generally 2.8 m in diameter and up to 6 m wide.
Available standard mesh apertures are:
Reps or Hollander’s Weave:20, 35, 55 or 90 microns
Plain Weave:112, 170 or 270 microns
The quality of the water and the efficiency of a microstrainer can be easily assessed using a BEAUDREY Colmatometer.
Typical values of the BEAUDREY PC are:
Lakes and reservoirs with visible growth: 1 to 6
Clear mountain lakes: 0.1 to 0.7
Rivers: 0.5 to 15
Rivers during floods: 100 or more
Sewage water entering tertiary treatment: 3 to 6
Microstrainers operate at constant water level.
Various arrangements are possible for plants with a number of machines.
ADVANTAGES OF BEAUDREY MICROSTRAINERS
Very compact water intake plant
Very low head-loss
Use no chemicals
Long-lasting mesh panels due to the bonded reinforcements
Virtually no maintenance required
Low-energy requirement (less than 15 kW per machine)
Well-proven and reliable
Stable and predictable efficiency
Delivered fully-assembled, ready for installation
Spray-water supply at 1 bar
Differential level monitoring system
PLC control cabinet
Pit isolation penstocks
BEAUDREY microstrainers are generally entirely built from austenitic stainless steel (AISI 304L and AISI 316L). For seawater plants, all AISI 316L construction (or better) can be supplied.