MBR Membrane Modules

MBR membrane modules are the core separation element in a membrane bioreactor (MBR) process. Submerged directly in the aerated bioreactor, the membranes replace the secondary clarifier of a conventional activated sludge system — retaining all biological solids and producing a near-sterile permeate with turbidity below 0.2 NTU and total suspended solids typically below 1 mg/L. PVDF (polyvinylidene fluoride) is the industry standard material for MBR membranes because of its chemical resistance to NaOCl and citric acid (the two principal CIP chemicals), its mechanical durability over 7–12 year service cycles, and its hydrophilicity after surface modification, which reduces organic fouling propensity. For a full process description of how an MBR plant is designed and operates, see our MBR technology page at /mbr-technology/.

MBR membranes are available in two primary configurations. Flat sheet modules consist of PVDF membrane cast on rigid support plates, assembled into vertical cassettes with coarse-bubble scouring air introduced from below each panel; this configuration tolerates high MLSS (up to 15–18 g/L), fibrous solids, and variable feed quality, making it well-suited to retrofitting existing activated sludge tanks and to municipal STPs receiving combined sewage. Hollow fiber modules use bundles of self-supporting PVDF fibers potted into cylindrical modules; air scouring is applied externally along the fiber bundle, and the configuration achieves higher packing density per cassette volume. Standard cassette areas range from 5 m² (compact package plant modules) to 500 m² per cassette for large municipal installations. For new-build MBR plants where footprint is critical, hollow fiber is often the more economical choice; for retrofit projects, flat sheet provides greater operational tolerance. Physical cleaning of flat sheet modules uses coarse scouring air and periodic membrane wiping; hollow fiber systems use air scouring combined with periodic backwashing (back-pulsing permeate through the fibers to dislodge foulants).

In India, MBR technology has become the dominant choice for new STP installations wherever treated water reuse is mandated or where site area is constrained. Municipal STPs for IT parks, hospitals, and residential townships regularly specify MBR because the permeate quality meets CPCB/NGT standards for toilet flushing, landscaping, and cooling tower make-up without tertiary polishing. Industrial ETPs in the pharmaceutical sector (see /etp-for-pharma/) and food processing use MBR to achieve consistent permeate quality for ZLD RO feed or direct reuse. NGT orders and CPCB guidelines requiring treated sewage reuse in water-scarce urban areas are the primary regulatory driver for MBR adoption across Indian tier-1 and tier-2 cities. Spans Envirotech supplies brand-neutral PVDF flat sheet and hollow fiber MBR membrane modules as OEM replacements for existing installed systems and as first-fit supply for new MBR plants, covering municipal STPs (see /stp-for-it-parks/ and /stp-for-hospitals/) and industrial ETPs across India.