According to the UN, almost one-fifth of the world’s population lives in areas experiencing water scarcity. By 2025, it is estimated that two-thirds will experience water shortages. Yet at the same time, vast amounts of wastewater are generated daily, most of which is dumped into rivers and seas without adequate treatment, creating health and environmental hazards.
So increased focus is being put on water reclamation and efficient wastewater treatment, with ever-stricter regulations. “More and more people are realising that wastewater is a valuable resource,” says Mai Møllekær, Managing Director of Alfa Laval Ashbrook Simon-Hartley. “With the right solution, reusing wastewater is environmentally, socially and economically beneficial. Alfa Laval offers two filtration methods that help turn municipal and industrial wastewater into clean water.”
MEMBRANE BIOREACTORS (MBR) are an increasingly common solution for producing exceptionally clean effluent from biological wastewater treatment processes. They treat over 4 million cubic metres of wastewater every day – a figure that is expected to triple by 2018
“Alfa Laval has developed a unique MBR technology, based on membrane filtration modules incorporating patented hollow sheet technology. Compared to other MBR solutions it offers improved safety, simplicity of operation, plus low operation and maintenance costs,” says Thomas Møller, Segment Manager for Water and Waste Treatment at Alfa Laval. “Our MBR solution proves its value every day at numerous installations worldwide. Several customers specifically chose this because of its exceptionally clean final effluent, which they can reuse.”
1. General description
The MFM (Membrane Filtration Module) from Alfa Laval is designed to boost efficiency and reduce operating costs for the filtration of biologically treated waste water of both industrial and municipal origin. This membrane filtration solution for membrane bioreactors (MBR) combines the best features from flat sheet and hollow fibre membrane technologies into the unique hollow sheet membrane design offered by Alfa Laval. Thanks to combining two technologies into one, Alfa Laval achieved many unique features of their modules, such as:
The unique design feature of the gravity operated Alfa Laval Membrane Filtration Module is that it operates with an exceptionally low transmembrane pressure (TMP) – up to 10 times lower than today’s technology - across the entire surface of the membrane. This means that the mixed liquor is not squeezed against the membrane surface.
A unique Alfa Laval design ensures that permeate (cleaned effluent) is drained from the entire surface of the membrane and that it emerges all the way round the edges, exiting through connectors at the top of the unit. This means the pressure drop over the membrane is close to zero and there are no dead spots on the membrane itself. This extremely low TMP means the membranes are significantly less prone to fouling, resulting in a longer lifetime and extended operating periods between cleaning.
Ultralow TMP The unique design feature of the gravity operated Alfa Laval Membrane Filtration Module is that it operates with an exceptionally low transmembrane pressure (TMP) – up to 10 times lower than today’s technology - across the entire surface of the membrane. This means that the mixed liquor is not squeezed against the membrane surface which reduces fouling and consequently the need for cleaning, resulting in a longer service life between replacements.
And when cleaning is eventually needed, it is easy to deal with the entire membrane surface effectively using cleaning sequences that include relaxation, back pulse, Cleaning In Place (CIP) by circulation.
There are many specific benefits resulting from Alfa Laval membrane filtration modules for end users, subcontractors and companies using Alfa Laval modules as components of their devices (see Table 1).
| Solution | Advantages and benefits |
| Utilization of the full membrane surface | Less fouling |
| Ultra low TMP – up to 10 times lower than hollow fibre and flat sheet membranes | Less fouling |
| Robust module design | Long module lifetime |
| Gravity-operated MBR | Simple system (fewer pumps and Simple control system needed) |
| Stackable design | Better utilization of scouring air – ma king it energy-efficient |
| Multiple cleaning methods – back flush, circulation and soaking | Easy cleaning |
| Strong PVDF membrane | Suitable for multiple applications |
| Compact design | High packing density |
