Large-Scale Applications

  • Two (4m x 2m x 2m) stainless steel MEL-BFs transported and installed

    MELlgscale2

    MELlgscale1

    MELlgscale2

  • General Specifications

    1. Standard tank dimensions vary from 1m x 1m to 8m x 8m. Alternative dimensions and geometries are available on request.

    2. Several tanks may be used to achieve desired capacity (minimum of two recommended). All filters operate completely independent of each other.

    3. Filters may be mounted on skids or other mobile platforms.

    4. Filter footprint including piping in front of filter including raw water inlet, filtered water outlet, wastewater outlet and backwash water inlet is similar to basic plan dimensions plus 1.5 meter at the front of filter.

    5. Tanks may be cast‐in‐place, stainless steel, marine grade aluminum, polyethylene or fiber glass. All components used are NSF 61 certified.

    6. Filter media meets AWWA B‐100 standards and is NSF 61 certified.

    7. Filtering media depth may vary from 15 cm to 80 cm as required. (Note that the 35 cm depth meets the minimum requirements for slow sand filters recommended by the AWWA and a 45 cm depth meets the Ten State Requirements.)

    8. Average maximum operating weight of filter, media and water is 2,250 kg/m2 of filter surface area (depends on the exact depth of media used).

    9. Manual control of raw water inflow, filtered water outflow, backwash, filter‐to‐waste and wastewater evacuation is standard.

    10. Flow into filter varies with application and regulatory requirements. Preferred pressure at the filter inlet is 5m head (after control valves and flow meter).

    11. Flow into filter is controlled using manual valves, flow meter at the filter and mechanical float valves inside filter.

    12. Backwash flow rate varies to 6 L/s/m2, pressure of 6 m at underdrain.

    13. Backwash is manually controlled and is monitored using a flow meter

    14. Control of raw water inflow, filtered water outflow, backwash, filter‐to‐waste and wastewater evacuation may be automated as required.

    15. All piping, including the underdrain, is normally constructed using schedule 80 PVC. Other materials may be used.

  • MEL-PF Implementation Guidelines

    1. Surface loading rates and media design are optimized and verified by bench and pilot scale testing.

    2. Surface loading rates can be more than 1,000 L/h/m2. Should be determined using bench scale or pilot scale studies.

    3. Basic filter design is based on AWWA guidelines for gravity slow sand filtration design and construction. Modifications to this design may be made as required or requested.

    4. Filter operation may be stopped and started as required. Practicality should be determined by pilot scale study.

    5. Filters may be cleaned using a backwash process using filtered water. Backwash flow varies between 2 to 6 L/s/m2. with a pressure head of 4 to 6m. (Backwash pump should be capable of providing up to 6 L/s/m2 with a pressure of 6 m at the underdrain.) Typical volume of waste water produced per backwash is 1 m3 per m2 of filter surface.

    6. Frequency of backwash depends on method of cleaning and the type and concentration of suspended sediment. Periodic physical removal of the captured material not able to be removed by backwash may be required.

    7. A brief filter-to-waste after backwash may be required and should be confirmed using pilot studies. Regulatory agencies may require a filter-to-waste procedure.

  • MEL-BF Implementation Guidelines

    1, When MEL-BFs are used as a substitute for traditional slow sand filters the media bed design, media material and filter operation meets AWWA recommended specifications and local construction and operation guidelines. (Use of the MEL-BF as a substitute for a slow sand filter is subject to regulatory approval if operated and cleaned using procedures different from traditional slow sand filtration.)

    2. Surface loading rates of the MEL-BF are similar to that for a traditional slow sand filter - up to 400 L/h/m2 depending on results of pilot studies and regulatory constraints.

    3. Filters may be demand operated (subject to pilot testing and regulatory approval).

    4. Frequency of backwash depends on method of cleaning and concentration of suspended sediment. See Note 6 MEL‐PF.

    5. Frequency of backwash depends on method of cleaning and concentration of suspended sediment.

    6. Filters may be cleaned using a backwash process using unchlorinated filtered water. Backwash flow varies between 2 to 6 L/s/m2. with a pressure head of 4 to 6m. (Backwash pump should be capable of providing up to 6 L/s/m2 with a pressure of 6 m at the underdrain.) Typical volume of waste water produced per backwash is 1 m3 per m2 of filter surface.

    7. A brief filter-to-waste after backwash may be required and should be confirmed during pilot studies. Regulatory agencies may require a filter-to-waste procedure.

    8. Note that if scraping and harrowing techniques are used it is recommended that provision be made for filter bed degassing between cleaning operations and brief filter-to-waste procedures.

    9. Filters may be temporarily decommissioned and re-commissioned as required without removal of media.