Enviro Process Engineering (HK) Co. Ltd.

安和環保工程(香港)有限公司

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Contra Shear Technology

CONTINUOUS SAND FILTERS:

new and improved technology for the cleaning of sand filters. Continuous  sand filters require no downtime for backwashing and have an absence of mechanical moving parts.

An innovative system of continuous sand filtration

Principle of Operation:

 SandFilterAqua.jpg (70677 bytes)

 

The dirty sand is continuously removed from the active sand bed (A) thanks to the action of the air-lift pump (C), which sucks the contaminated sand from the bottom (B) of the filter body. A mixture of sand, dirty particles and water is transported upward through the air-lift pipe into the washing chamber at the top of the filter.

The separation of impurities from the sand takes place in the exclusive washing system. This is accomplished through the simultaneous action of both counter current water and air injected at the bottom of the washing chamber. The sand is returned by gravity to the top of the active sand bed (A) after being routed downward through a labyrinth of several settling steps.

The feed water is fed into the filter at the base of the active sand bed through the distribution ring (D). It then flows upward through the downward moving sand bed where the solids are intercepted. The clean filtrate exists the filter through the overflow weir (E). The continuous reject flow of washing water is discharged through a separate outlet.

Main Advantages:

  • Unique continuous back-washing system uses 50% raw water in place of filtered water;
  • High efficiency in removing fine solids including colloidal particles;
  • Easy maintenance thanks to the fully external sand air-lift system;
  • Easy installation;
  • Very low operational head loss allows gravity feed in many instances;
  • Low capital and operating costs;

Typical applications:

  • Surface water filtration
  • Drinking Water treatment
  • Municipal/industrial WWTP (primary filtration)
  • Municipal/industrial WWTP (tertiary treatment)
  • Mill scale cooling water treatment
  • Algae removal
  • Pre-treatment for membrane ultra-filtration plant
  • Pre-treatment for ozonisation treatment plant
  • Final treatment with active carbon
  • Biological denitrification

 

Mod

H

(mm)

(mm)

Net filtration area

(m)

Sand bed average height

(m)

AQF 3

4700

2000

3

1.4

AQF 3/2

5200

2000

3

1.9

AQF 5

5800

2500

5

1.6

AQF 5/2

6300

2500

5

2.1

Material in Stainless steel or other special constructions on request

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Room 1019, Nan Fung Comm. Ctr., 264-298 Castle Peak Road, Tsuen Wan, N.T. Hong Kong

香港新界青山道264-298号南豐商業中心1019

Tel 电話: (852) 2611-7376   Fax 傳真 : (852) 2617-5716   E-Mail电郵 : envirohk@netvigator.com