The updated EU Urban Waste Water Directive (UWWTD) sets a new and higher standard for urban wastewater treatment. For many wastewater treatment plants, the stricter requirements for phosphorus (P) and suspended solids (TSS) discharges mean that current treatment processes are no longer sufficient.
Many of our customers ask us: How do we upgrade our systems to capture the smallest particles and comply with legislation – without massive construction or cumbersome maintenance?
One of the possibilities lies in advanced cloth filtration. Veolia has developed the Hydrotech* Cloth Filter: Confidence Series for this very challenge.
To help you navigate your upgrade options, we have answered the most common questions we receive from utility companies about phosphorus and TSS reduction.
Facts about our cloth filters
✓ Reduces TSS to < 5 mg/l
✓ Reduces phosphorus to < 0.1 mg/l
✓ No polymer dosing required
✓ Compact plug-and-play solution
✓ Filter panels weigh only 3 kg when wet
✓ Increased safety for the user
How does Hydrotech Cloth Filter technology work?
The Hydrotech Cloth Filter uses a pile cloth technology with a very high number of individual fibres. This creates a large specific surface area, giving a nominal particle removal down to 5 microns.
How well does the Hydrotech Cloth Filter handle strict emission limits, especially for phosphorus?
With Hydrotech Cloth Filters you can achieve a robust reduction of total suspended solids (TSS) to less than 5 mg/l and phosphorus to less than 0.1 mg TP/l.
Veolia offers cloth panels with nominal 5 or 10 micron openings.
Does phosphorus removal require us to add polymer?
No - and that is one of the biggest operational advantages. Hydrotech Cloth Filter does not require polymer dosing to achieve high phosphorus removal. It is typically sufficient to add an iron salt or aluminum salt as a coagulant upstream of the filter. This significantly simplifies daily operation and reduces chemical costs.
Is there a difference between using iron salt or aluminum salt in the Hydrotech Cloth Filter?
No, no significant difference has been observed with the cloth filter.
Will there be problems with sedimentation of particles at the bottom of the tank with outside-in-filtration?
Veolia has designed a perforated pipe system at the bottom of the tank that automatically removes sludge from the bottom. To make sludge extraction more efficient, the tank has an asymmetrical shape that collects sedimented particles where the pipe system is mounted.
If I have a Hydrotech Disc Filter, can I replace the filter panels with Cloth filter panels?
No, you can't. On a traditional disc filter, the filtration will be from the inside out, whereas on a cloth filter, the filtration will be from the outside in. The two technologies are not “interchangeable”.
We are short of space. Does the filter require major construction work?
This can largely be avoided. The Hydrotech Cloth Filter can be supplied as a complete plug-and-play steel tank solution. The compact solution is ideal for existing plants as it requires minimal construction work and can be easily integrated into the plant's existing infrastructure.
How difficult is maintenance for our operations staff?
The Hydrotech Cloth filter has been developed with health and safety as a fundamental design principle. The parts that require routine maintenance are mounted on the outside of the filter, allowing technicians easy and safe access.
Each filter panel weighs only 3 kg when wet. This means that a technician can safely remove the panels by hand – without a crane and without heavy lifting.
What options are there for cleaning filter panels?
High-pressure cleaning, chemical cleaning or a leasing agreement with Veolia, where the dirty filter panels are replaced with clean ones.
How often should the filter panels be cleaned?
The frequency of cleaning depends on the process and cleaning method:
High pressure cleaning is typically performed once a year.
Chemical cleaning is typically performed 2-3 times a year and can be done in two ways:
Spray directly onto the panel – requires a smaller amount of chemical solution
Immersion in chemical solution – requires a significantly larger amount of chemical solution
Is operation interrupted when the filter panels are cleaned?
At the typical cleaning sequence (with permanently mounted “vacuum cleaner heads” on each side of the disc), operation will not be interrupted. In the event of chemical or high-pressure cleaning the filter will be taken out of service.
What is "panel leasing" and how does it save us time?
If you have limited resources for maintenance, you can choose a service agreement, where Veolia technicians come out and replace the used panels with clean ones. The dirty panels are washed at our factory. This is a leasing agreement where Veolia owns and services the panels. For you, this means lower CAPEX, fully predictable operating costs and minimal downtime.
Can we test the technology at our own facility before investing?
We offer mobile pilot plants in containers that can be set up directly on your site. We have recently done this with great success at, among others, Avedøre and Næstved wastewater treatment plants in Denmark, where over 50 representatives from Danish utilities came to see the technology in operation – and see how it meets future phosphorus requirements.
How do I calculate the necessary filtration area for my treatment plant?
To calculate the exact filtering area (number of discs and filter units) needed to treat your water flow, we need to evaluate a few specific design parameters. Please contact your local Veolia representative, who will help assess your current setup and determine the precise filtration requirements for your plant.
Watch this 1-min video to see how easy it is to access and remove the lightweight panels on the Hydrotech* Cloth Filter Confidence Series.
Are you ready to take the next step?
Contact us for an assessment of your current process line and hear how Veolia can ensure your compliance with the new UWWTD requirements.