Fine Screening

Step Screen


step screen

Step screens are a regular feature on treatment plants throughout
New Zealand. We have chosen the Sam McCoy step screen
because it uses:

  • thicker steel to handle tough operating conditions
  • deeper and higher steps, so that larger screenings are removed and don't fall back into the channel requiring manual removal
  • main bearings are above the waterline, requiring less maintenance and lasting longer

The Sam McCoy step screen is an alternative to currently available systems with a deserved excellent reputation for reliability and ability to handle tough operating conditions.

Sam McCoy screens originate from a European design originally built under license for many years at Sam McCoy's factory in Malaysia. Sam McCoy utilizes high precision German manufacturing machinery and each of their screens is supplied with full quality control certificates for materials, fabrication and testing prior to dispatch. Fabrication in Malaysia has the added advantage of short delivery times to New Zealand.

References are available from installations in Australia and New Zealand.

Simplicity of Function

Emphasis has been placed on reliable performance and ease of maintenance. All FSS screens are robust units made in either stainless steel 304 or 316.

The FSS Screen bars are teeth formed (termed lamellas) with half the lamellas mounted to a fixed frame and the other half to a moveable frame. These evenly spaced stepped lamellas trap solids and fine particles but allow liquid to pass through.
The solids build up on the lamellas which rotate lifting the mat step by step up the screen to be discharged at the top. This lifting action, coupled with the retention time on the screen, help in the dewatered screenings process.

The screening lamellas are anchored in place along the whole length of the unit ensuring rigidity and accurate spacing. The FSS screen's unique fixing arrangement allows for easy exchange of individual blades should the need arise.

Standard slot widths for the screen are 3mm or 6mm with corresponding standard screen sizes. Other dimensions are tailored to fit the requirements of the plant.

Related Equipment

Installation at Ngaruawahia read more...
Installation at Pukekohe read more...

Brickhouse Technologies LTD is able to advise which screen will be the optimal solution for your application in respect to technology, aperture and required removal efficiency. Brickhouse Technologies LTD will not just sell a screen, Brickhouse Technologies LTD will provide a solution which fits within the larger design of your treatment plant.

Rotary Drum Screen Above channel


milliscreen

Contra-shear® Milliscreen®
by Johnson Screens Australia

The Contra Shear Milliscreen is the industry standard when it comes to rotary fine screening.  The Contrea Shear was developed in NZ over 35 years ago as the world’s first rotary screen.  It’s self-cleaning, internally fed rotary screen with a range of slot sizes and gap types is suitable for a large range of industries and process streams with years of research and over 15,000 installations worldwide, Johnson Screens® has by far the most diverse application experience in the industry.
The Milliscreen is commonly installed above channel with the influent either pumped or flowing by gravity into the screen.  A weir tank inside the screen drum balances the flow and distributes it evenly over the rotating screen drum.  Solids are captured inside the screen drum where they are de-watered and discharged using a series of diverter plates.

The Milliscreen drum is cleaned by using water under moderate pressure through two sets of sparge pipes that operate intermittently through a control system.

The wide range of Milliscreen models are capable of handling flow rates from 0.6 to 3,360 m³/hr. Slot sizes from 0.25 to 6.0 mm with Vee-wire models and from 1.0 mm and up with perforated plate and mesh models.

Rotary Drum Screen in-channel (Suboscreen)


Suboscreen

The Suboscreen from Johnson Screens is a self-cleaning, in-channel, semi-submerged rotary fine screen capable of handling high flow rates and is suitable for both municipal and industrial applications. The influent entering the Suboscreen changes direction through 90 degrees as it exits the screen resulting in a high capture of solids.

The self-cleaning rotary drum is installed semi-submerged in a channel resulting in a smaller foot print compared to competing screens. The Suboscreen includes an integral drainer screw press for screenings washing, dewatering and discharge.

The operation of the Suboscreen is normally linked to the level differential between the upstream and downstream levels in the channel. 

The Suboscreen is capable of handling flow rates from 1,440 m³/hr to 14,400 m³/hr through a single unit. Slot sizes range from 0.5 mm to 6 mm on the Vee-Wire® models and 2 mm upwards on the perforated plate and mesh models.

Screen Compactor


Johnson Screens’ screen compactor is a cost effective integrated machine consisting of a screen, a shaftless spiral and a press unit.

Solids from the incoming flow collect onto the screen mesh and cause it to gradually blind. The upstream water level rises and at a predetermined level, the spiral will be activated. Brushes fixed to the periphery at the lower section of the spiral will then clean the screen mesh and convey the solids up to the pressing zone.

The solids or screenings are compacted and dewatered and depending upon the solid properties, a volume reduction of around 40 percent dry solids or greater can be achieved prior to discharging the screenings. Washing can also be incorporated in the screening, transport and/or compaction zones.  Faecal matter washing efficiencies greater than 90 percent can be achieved.

Options include installation in a channel or delivered in a stainless steel tank.  Other variants include the vertical screen and the minyscreen

The SC range of screens is extremely cost effective – lower outlay and operational costs without any compromise to performance, reliability or asset life.

Flow Capacities

Up to 1080 m³/hr depending upon effluent and solids contained within the flow.

Screen Size Availability

• 0.25, 0.5, 1, 2 mm in wedge wire
• 2 - 7 & 10 mm perforated holes

Inclined Drum Screen (Versa)


versa

Johnson Screens® Inclined Rotary Screen – Versa design is unique in the sense that the inlet end of the screen does not have a bearing and also does not have any fixed or rotating arms; the inlet end of the screen is free. The Versa design also results in a lower headloss across the screen. It is an integrated piece of equipment consisting of a screen drum, a screw conveyor and compactor.

During operation, solids in the incoming flow greater than the opening size progressively collect inside the screen drum causing it to gradually blind. The upstream water level rises on account of the reduction in open area and at a predetermined level differential, the screen drum and screw conveyor start rotating while immersing a clean section of the screen into the effluent.

The rotating action of the screen drum causes solids or screenings to be lifted up and dropped into the screw conveyor trough. Spray nozzles and a roller brush (installed on perforated plate screens) fixed to the periphery of the screen drum cleans away any residual solids from the screen surface.

As the water level falls, the screen drum will also stop rotating. However the screw conveyor will continue to rotate for a predetermined length of time to convey all residual solids into the compaction zone before it stops.

Curved Fine Rake Screen


rake screen diagram

Brickhouse Technologies LTD is pleased to offer the curved and flat raked inlet screens by Werkstoff + Function to the New Zealand market. Based on one of the oldest screen designs in the wastewater industry this equipment has been optimized to fit the stringent requirements of the European market.

The advantages of curved and flat fine rake screens is in their simplicity and reliability. With a minimum of moving parts and all bearings above the water line, they are extremely rugged and are practically maintenance free. They are ideally suited for small to medium sized treatment plants or remote locations where other screens such as step screens or basket screens would be too maintenance intensive.

Rake screen gap sizes range from 0.5mm up to 8.0mm and allow for quick change in replacement of screens after installation.  The curved rake screen comes as an above ground package which inlet water is pumped into and the flat rake screen is an in-channel version.

Screw presses are generally integrated into the screen design to wash, compact and dewater the screenings. 

With many references from Europe, the W+F screens offer an alternate inlet screen up to 2880 m³/hr which may best meet the demands of your treatment requirements. 


Flat Fine Rake Screen


Flat fine rake screen

Werkstoff and Function manufacture a Flat Fine Rake Screen as a reliable screening option. The Flat Fine Rake Screen is a solid and simple design.  It is suitable for high flows in narrow channels with the screen surface area twice the width of the channel.  With only the screen and rake in contact with the influent this is a low maintenance screen.

The rake scrapes the screenings up the screen and into the conveyor or compactor at the top of the screen. The rake travels from the bottom of the screen, which prevents problems with sediment in front of the screen.  An intensive washing system can be fitted to remove organics and sand from the screenings if required.

Gap width 0.5 to 8.0mm
Channel widths up to 2500 mm
Channel depths up to 1800 mm

Minyscreen


Minyscreen

Likely the smallest, low-cost screw screen available in today's market, the Johnson Screens® Minyscreen is an integrated machine consisting of the screen, a spiral and a press unit. During operation, solids in the incoming flow will progressively collect onto the screen.

At a pre-set inlet water level, the spiral will be activated and convey the solids up to the pressing zone; brushes fixed to the periphery at the lower section of the spiral will clean the screen. Solids or screenings are compacted and dewatered and, depending on the solids properties, a volume reduction of around 40 percent can be achieved prior to discharging the screenings into a container.

Supplied either as a complete package with polypropylene tanks or just the Minyscreen itself, it can provide an extremely cost effective solution to variable screening applications. Typical applications include small sewage treatment works, industrial effluents, process liquid and fluid screening, sludge and scum screening, and commercial applications such as restaurants and fast food outlets, laundries, car washes, etc.

Flow Capacities

414 L/min (25 m3/hr) depending upon effluent and solids contained within the flow

Screen Size Availability

• 2, 3, 5 and 6 mm perforated holes

Externally Fed Rotary Screens


Rotary Screen

Johnson Screens Externally Fed Rotary Screen is ideally suited for process and wastewater streams containing high fats, oils and grease loadings. The system operates by feeding the influent into a headbox, which distributes the flow evenly across the full length of the rear and upper external surface of the rotating drum.

As water passes through the screen, solids are retained on the outside of the screen drum and are carried by rotation around to the front of the screen. A fixed doctor blade (with adjustable tension) removes the solids from the screen. The screened water cascades down inside the drum and falls through the bottom, creating a vigorous backwash action.

This action, together with the use of internal water sprays, has a combined effect of self-cleaning the drum during each revolution.

Centre-Flo Band Screens


centre flo

Johnson Screens Centre-Flo is an in-channel, ‘in to out’-type travelling band screen suited for screening water and wastewater. The design is unique and well suited for high flow rates with narrow and deep channels where other types of screens don’t easily fit. Its modular design integrates screening, washing and dewatering of screened solids in a single compact unit. 

The operation of the Centre-Flo is normally linked to the pressure differential between the upstream and downstream levels in the channel.

The Centre-Flo is capable of handling flows of up to 6,480 m³/hr through a single unit.

Screen Screw Compactor – Vertical


Screen Screw Compactor

Designed to be installed into sumps, manhole chambers, underground chambers, pumping stations, etc. Johnson Screens® Screen Screw Compactor - Vertical provides a solution to facilitate lifting, washing, dewatering, compaction of solids and improving the performance and reliability of drainage systems.

Screen Screw Compactor – Vertical  are integrated machines consisting of a screen, spiral and a press unit. During operation, solids in the incoming flow will progressively collect onto the screen.

At a preset inlet water level, the spiral will be activated and convey the solids up to the pressing zone; brushes fixed to the periphery at the lower section of the spiral will clean the screen mesh.

The solids or screenings are compacted and dewatered and depending upon the solid properties, a volume reduction of around 40 percent dry solids or greater can be achieved prior to discharging the screenings into a bin.