Water and Waste Water treatment Systems

UF membrane is made from high-grade polymeric PVDF material to form a hollow fiber membrane that is very durable and less prone to breakage. The hollow fiber has a dense layer or skin on both the inside and outside surfaces, forming a double-walled structure that contributes to its strength. In addition, its fouling resistance is improved by making the membrane surface more hydrophilic than the underlying PVDF polymer. With uniform pore size and outside-in flow, the UF membrane creates a barrier without sacrificing performance.

How Ultrafiltration Works :

• UF modules utilize a double-walled hollow fiber H-PVDF membrane with a very small pore diameter for excellent removal of particulate matter and bacteria, and most viruses and colloids. Despite the small pore diameter, the membrane has a very high porosity, resulting in a stabilized flux similar to that of micro-filtration (MF). Typically, UF is operated at a constant permeate flow. The transmembrane pressure (TMP) will naturally increase over time, and the module can be cleaned by back-washing and air-scouring to remove the fouling layer for longer service life.

Advantages of UF Technology :

• Low fouling : UF modules are made from H-PVDF material, which has excellent chemical resistance to strong levels of disinfectants such as peroxide or hypochlorite, allowing sufficient removal of bacterial growth.
• Very fine pore diameter : With a nominal pore diameter of 0.03 μm, UF technology effectively removes pathogens, most viruses and bacteria. In addition, the membrane’s high porosity allows high flux operation at a given transmembrane pressure.
• Durable double-walled fiber structure: The distinct structure provides excellent durability and resistance against breakage, even with periodic cleaning procedures to remove fouling.
• Outside-in flow configuration : Systems designed with UF use an outside-in flow configuration, which allows for low clogging and high solids loading, high flow area and easy cleaning.
• Dead-end or concentrate bleed capabilities : Although the primary flow design is dead-end filtration, modules can be easily adapted to a concentrate bleed mode. Simple, modular design: UF modules can be configured in a simple modular design providing a compact footprint.

The Ultrafiltration membrane system has been specifically selected and designed to treat the secondary treated sewage. The UF is a skid mounted membrane system, which comprises mainly of the hollow fiber UF membrane modules, re-circulation and pneumatically actuated valves. All these are neatly interconnected into a compact and modular train, which comes complete with a slave control system.

The proposed UF System consists of one train to produce a net UF filtrate capacity of 3.0 to 3.5 m3/hr/module for Reuse as per your requirement. The UF system is incorporated to further reduce the Secondary Treated Domestic Waste Water turbidity to less than 0.3NTU and SDI less than 3.0 at all times. Each UF membrane module consists of thousands of hollow fibre membranes that are capable of removing virtually all suspended solids, colloids, bacteria and viruses bigger than 0.01- 0.015miron from the feed stream. A detail description of each train and membrane module is listed as followed:

The UF system consists of the following modes of operation :

UF Backwash (BW)

• With the accumulation of solids during filtration, the resistance to flow will increase which can be overcome by subjecting the membrane to a reverse flow, with the product water Air-scouring is also introduced concurrently to improve the effectiveness of the Backwashing. This backwashing operation is carried out periodically which can be predetermined by either total flow or elapsed time. The overall system will be controlled such that only 1 train will undergo backwashing at any one time. The backwash stream is discharged to the waste sump.

Maintenance Cleaning (MC)

• To maintain optimum filtration efficiency, periodic chemical cleaning of the membranes is required. MC is an automated sequence meant for short-term regaining of permeability, which is a short duration cleaning with chlorine and citric acid as per pre-set schedule with minimum stoppage of the system. The frequency of maintenance cleaning is dependent on the raw water quality and its variation. The expected frequency of this short term cleaning is once in a week.

Recovery cleaning (RC)

• An extensive cleaning procedure requires longer stoppage on a process train for permanent regaining of the membrane permeability and performance. The membranes are subjected to a regime of soak and flush cycle which will remove the foulants or contaminants that cannot be removed by backwashing alone. Similar to MC, frequency of RC is dependent on the feed water quality and its variation; the expected frequency of this long term cleaning is once in 4 to 6 weeks.