Monolithic Filter Underdrain
- Without Joint
- High Strength, Light Weight
- Stable Under Outdoor Conditions
- Even Water and Air Distribution

‘GT’ Monolithic Filter Underdrain is poured without any joint, and the concrete is poured and shaped at one time on site, which makes the filter plate good in integrity and high strength. Adjustable filter head adjusts the filter head level with high precision, which can adjust the air distribution hole of the whole filter pond to the same level elevation, thus distributing water and air more evenly. The overall casting filter plate is easy to transport and install, with short construction period and low cost. The air and water distribution is even, and the backwashing effect is good. The filter media is thoroughly cleaned and the amount of backwashing waste water is small, thus the operating cost is lower.
‘GT’ Monolithic Filter Underdrain comes with different plate size design with different number of nozzle sets per plate.
1. 49 nozzle sets (964mm x 965mm)
2. 36 nozzle sets (650mm x 650mm)
Customised plate can be made to depending on the filter tank size and thickness of dwarf wall design.
Operation and maintenance of monolithic filter underdrain are simple and straightforward. Maintenance is required for the nozzle sets through regular backwashing of filter tank using pressurised water is sufficient.
| Monolithic Filter Underdrain Specifications | |
| Material | ABS |
| Shape | Rectangular |
| Thickness | 5mm |
| No. of Nozzle Sets | 49/36 |

Filter Nozzle
‘GT’ adjustable filter Nozzle is made of PP and ABS engineering plastics, with high strength and long service life. It is used in conjunction with the filter plate and has an adjustment function.
Features:
- The filter cap with even 0.3mm/0.4mm/0.5mm slots prevent the filter material from entering and give high free surface.
- The filter rod is provided with an adjusting thread, which can be adjusted up and down, and is equipped with an adjusting flap to cooperate with the adjusting flap in the pre-embedded seat to control the adjustment accuracy of the filter rod and fix its position at the same time.
- There is an air inlet slit on the filter rod, and the air is evenly distributed during backwashing.
- The pre-embedded seat has a bayonet pin for easy fixing on the panel.
| Specifications | |
| Material | PP and ABS |
| Shape | Column |
| Filter Rod Length | 365mm |
| Adjustable Height | ~50mm |
| Slot Height / Width / Qty | 34mm / 0.3mm or 0.4mm or 0.5mm / 36 |
Installation Records
| Project Title | Year |
| 1. Cadangan Pembinaan Loji Rawatan Air Ngoi-Ngoi 2 (150JLH) Pakej 1: Membina dan Menyiapkan Sebuah Loji Rawatan Air Berkapasiti 150JLH Serta Kerja-Kerja Berkaitan di Kawasan Ngoi-Ngoi | 2023 |
| 2. Projek Menaiktaraf Loji Rawatan Air Jenun Baru dari 55 MLD kepada 110 MLD di Daerah Pendang, Kedah Darul Aman | 2024 |

Multiblock Underdrains
The MULTIBLOCK underdrain structure is composed of a water supply chamber and a dispersion chamber, and there are multiple holes in the inner and upper orifice plates of the block. Air and water are evenly distributed during backwashing. Lightweight approved HDPE structural foam construction simplifies installation, while providing corrosion resistance.
The MULTIBLOCK design has reduced the ineffective area. The spacing between the filter pores of the block is between 5-7cm, and the pore spacing is small providing a 250 filter holes/m² which minimize blind spots and hence resulting in an equal and uniform distribution of water and air. The upper orifice plate is set as a cross-radial structure (beyond the 3mm protrusion of the upper end of the orifice plate) that can avoid the blockage of the orifice plate, and the radiant water and air can be evenly diffused during backflushing. The upper orifice plate can be equipped with a porous support plate, which can enhance the distribution of backwash water and backwash air more evenly. Moreover, the gravel layers are easy to be laid.
Features:
- Lightweight
- Simplified installation
- Even and uniform distribution
- Optimize air scour capabilities
- Corrosion-resistant design
- Minimizes depth required
| Specifications | |
| Dimension | 1200mm (L) x 270mm (W) x 300mm (H) |
| Weight | Approx. 11.5kg |
| Diameter of orifice holes | 2.5mm |
| No. of orifice holes | 1,000/block |
| Backwash rate (water) | 0.25m³/min/m² |
| Backwash rate (air) | 1.50m³/min/m² |
