Tertiary Filtration Solution for Water and Wastewater Treatment

For many sewage plants where secondary wastewater treatment is not sufficient to meet local authorities’ increasingly stringent effluent criteria for discharge into nearby water courses, tertiary treatment such as final polishing is needed. At the same time fresh water is a scarce and very expensive resource in many regions, and many are looking for alternative water resources such as reclaimed wastewater for reuse. Alfa Laval has a solution that solves both challenges.

Superior effluent quality and certified for water reuse

The Alfa Laval AS-H Iso-Disc® Cloth Media Filter is a polishing filter that removes suspended solids from wastewater to produce a high-purity, reuse-quality filtrate that can safely be either discharged to nature or immediately reused for both municipal and industrial applications. The performance of the Iso-Disc filter is second to none. The standard cloth media is capable of solids capture to less than 10 microns, with the advantage of outside-in depth filtration for handling high solids loadings.

The Iso-Disc Cloth Media Filter is California Title 22 Certified for Water Reuse Standards, and produces effluent of such a high quality that it is suitable for immediate water reuse as it is e.g. for irrigation, cooling towers or recreation lakes.

Small footprint-to-flow ratio and easy to retrofit

Iso-Disc polishing filters are a compact, cost-efficient alternative to traditional sand filters and other disc filter technologies. They offer a robust yet simple design that can handle peak hydraulic loadings up to 15 m³/h/m2 and filtration needs from <5 to >800 m3/h within a single small footprint-to-flow ratio filter. Compared to sand filters, Iso-Disc cloth media filters require substantially less space, significantly lower capital costs and less backwash water reject. Thanks to the flexible design Iso-Disc filters are easy to fit into new or existing tanks.

Simple, cost-effictive operation with minimal maintenance

The Alfa Laval AS-H Iso-Disc Cloth Media Filter utilizes a fixed cloth media for fully automatic outside-in depth filtration. An efficient linear backwashing system cleans the media equally across the whole surface area. Compared to other disc filter technologies Iso-Disc has a very high efficiency provided by the completely submerged filter elements that offer 100% utilisation of the filtration area plus the possibility for individual filter element monitoring, maintenance and effluent sample taking.

Another contributor is the fact that Iso-Disc continues filtration even during backwash and maintenance. It is very reliable and operator friendly, and requires minimal supervision.

Municipal and industrial applications In addition to municipal wastewater plants, Iso-Disc polishing filters can be used in a variety of industrial wastewater applications such as dairy, vegetabale washing and processing, beverage, brewery and distilleries plus the biological effluent associated with petrochemical production. It is especially suitable as final polishing filter after biological wastewater treatment such as activated sludge processes, oxidationditches, biological packaged plants, sequencing batch reactors (SBR) and fixed film processes (IFAS, MBBR and trickling filters).

Customer value examples

Iso-Disc has proven its value at numerous installations around the world. In Italy, Ecoimpianti Srl, who operates Umbria Acque’s Castiglione del lago wastewater treatment plant has adopted Iso-Disc as a means of reducing final effluent suspended solids and phosphourous. Other examples include Scottish Water, who replaced old sand filters with Iso-Disc filters that deliver a far superior final effluent quality than what is required by the local authorities, and City of Meadows Place in Texas, US, who saves $ 25,000/year in fresh water fees using reclaimed wastewater filtered with Iso-Disc in their new lake for recreational purposes.