NEW: the LEAP technology: easier to manage and less energy
1. ZeeWeed® Membrane description
ZeeWeed®-based wastewater and water treatment is a low energy immersed membrane process that consists of Outside-in, hollow-fiber modules immersed directly in the feed-water. The small pore size of the ZeeWeed® membranes ensures that no particulate matter will pass into the treated water stream. Thereby the ZeeWeed® ultrafiltration membrane system can easily remove particles and suspended solids. Furthermore, if dissolved components are converted to insoluble species upstream, the membrane will subsequently remove them as well. Figure 1 and 2 show a ZeeWeed® fiber in operation and a fibre cross section.
Advantages of ZeeWeed® are:
- No risk of fibre plugging due to Outside-In filtration process
- High mechanical strength due to reinforced hollow fibre
- Excellent rejection for particles, suspended solids and microorganisms due to ultrafiltration pore size (figure 3)
- Efficient cleaning procedures due to backwashable membrane
- Low footprint filtration tank design due to optimal packing density
- Excellent chemical resistance due to high quality PVDF membrane materia
Depending on the required capacity, a full-scale ZeeWeed® treatment facility is comprised of a given number of modular components: modules, cassettes, and trains. By this modular construction plant expansion can be done easily. Figure 4 illustrates an individual ZeeWeed® membrane module, which is the building block and smallest replaceable unit of the ZeeWeed® filtration system. A module consists of thousands of membrane fibers, oriented vertically between two moulded plastic headers. Membrane modules are joined together to form a cassette (Figure 5), which is the smallest operable unit of the filtration system. Each cassette is connected to a common permeate (filtrate) header.
A ZeeWeed® street (Figure 6) is a production unit containing a number of cassettes immersed in an open tank. A full-scale ZeeWeed® facility treats water with one or more
trains. The ZeeWeed® immersed membrane system can easily remove particles and suspended solids due to its small nominal pore sizes. Furthermore, if dissolved components can be first converted to insoluble species, the membrane will subsequently remove them as well.
Permeation and Backwash
The ZeeWeed® system operates under a low-pressure vacuum that is induced within the hollow membrane fibers by a connection to the suction side of a permeate pump. Operation alternates between permeation and backpulsing. Permeation refers to the period of time, when treated water is drawn through the membrane fibers by vacuum and is pumped through the permeate piping for its ultimate end-use. During backpulsing, filtered water from the backpulse tank is passed from the inside to the outside of the membrane to disrupt any particles that may be physically lodged in the membrane interstices. Figure 7 illustrates permeation and backpulse operation with a ZeeWeed® 500 cassette.
As clean water is pulled through the membrane during permeation, solids are left behind and the process tank becomes ever-increasingly concentrated. It is thus necessary to control the solids concentration in the filtration tank by rejecting process tank fluid, either continuously or by performing tank drains, depending on the chosen process strategy. Airflow may intermittently be introduced at the bottom of the membrane module to create turbulence that scrubs and cleans the outside of the membrane fibers. This reduces the solids accumulation on the membrane surface. Alternatively, in drinking water applications, aeration may only be turned on during backwash and/or, when performing a tank drain.
Membrane Cleaning
Periodically, the process tank is emptied to perform a maintenance clean, whereby the tank is drained and a chemical solution (typically caustic or acid) is either recirculated or backpulsed through the membranes. Chemical residuals are flushed from the membranes and process tank before the system resumes production. Maintenance Cleans are suitable to maintain the permeability of the membranes and to disinfect the permeate pipe work. Maintenance Cleans are carried out automatically, during which chemicals are added to the permeate backpulsed through the membrane. A Recovery Clean may be necessary from time to time to fully recover the permeability of the membrane. . Chemicals used could be hypochlorite, hydrogen peroxide, caustic or acids, depending on the nature of the fouling.
2. Process Description
ZeeWeed® Membrane Bioreactor (MBR) System
ZeeWeed® MBR process is a KAMPS technology that consists of a suspended growth biological reactor combined with an ultrafiltration membrane system, using the ZeeWeed® hollow fiber membrane (Figure 8). ZeeWeed® ultrafiltration membranes are immersed in an aerated tank in direct contact with mixed liquor. The ultrafiltration system replaces the solids separation function of both, secondary clarifiers and sand filters in a conventional activated sludge system.
ZeeWeed® MBR technology effectively overcomes the problems associated with poor settling of sludge in conventional activated sludge processes. ZeeWeed® MBR technology permits bioreactor operation with considerably higher mixed liquor solids concentrations than conventional activated sludge systems that are limited by sludge settling.
The ZeeWeed® MBR process is typically operated at a mixed liquor suspended solids concentration in the range of 8 to 12 g/L. Elevated biomass concentrations allow for highly effective removal of both soluble and particulate biodegradable material in the waste stream. The ZeeWeed® MBR process combines the unit operations of aeration, secondary clarification and tertiary filtration into a single process, producing a high quality effluent, simplifying operation and greatly reducing space requirements.
3. The advantages using a ZeeWeed® MBR
- Effluent Quality
High quality effluent from the ZeeWeed® MBR system meets the most stringent regulatory requirements and is ideally suited for reuse applications such as irrigation, aquifer recharge and industrial reuse.
- Nutrient Removal
Depending on the specific application and design requirements, a ZeeWeed® MBR plant can achieve either high quality nitrified effluent or, with the addition of an anoxic zone, high quality denitrified effluent. Phosphorus removal is readily achieved through biological means and/or by chemical precipitation with metal salts.
- Stable Process
Since the ZeeWeed® MBR plant is typically operated at low organic loading rates, and the membrane provides a barrier to discharge of particulate matter.
- ZeeWeed® MBR effluent quality is not susceptible to hydraulic or organic surges which can negatively affect effluent quality in conventional activated sludge and fixed film plants.
- Small Footprint
The ZeeWeed® MBR process operates at substantially higher mixed liquor suspended solids (MLSS) concentrations than conventional activated sludge processes. This allows an overall plant footprint which is substantially smaller than that of conventional wastewater treatment plants. Additionally, the compact footprint allows for the expansion of plant capacity within existing conventional plant basins in many instances.
4. Applications
- Picture 1: Municipal Wastewater BRM 750 m3/h
- Picture 2: Landfill Leachate Treatment 150 m3/day
- Picture 3: Industrial Waster Treatment 15 m3/h
- Picture 4: Drinking Water Treatment 60 m3/h
