Highland Spring’s Blaen Twyni site in the Brecon Beacons produces flavoured drinking water for various retail outlets, including supermarkets.

The site draws borehole water that is processed, flavoured, and bottled for distribution. During production, flavourings, preservatives, and cleaning agents are used. The resulting wastewater comprises product residue, cleaning fluids, raw water, and chemicals for pH balancing.

The site's existing wastewater treatment plant, consisting of eight sequential ponds or lagoons, was installed. Unused borehole water was used to dilute the final effluent. However, the system struggled to maintain performance, leading to costly off-site effluent disposal. Highland Spring approached ARM Ltd to assess and improve the wastewater treatment system, taking into account potential future increases in production.

The attributes of the waste stream were:

  • Average flow: 60m³/day (up to 350m³/day at peak)

  • Average BOD: 400mg/l

  • Average TSS: 21mg/l

  • Average COD: 570mg/l

  • pH range: 2-12

The system faced significant variations in load, with COD levels fluctuating between 0 and 1,500mg/l. These variations were partly due to insufficient flow balancing upstream and the pH adjustment system regularly being overworked, leading it to shut down frequently.

After analysing the flows and loads, ARM designed and installed a reedbed treatment system. To optimise the existing system, ARM converted one of the ponds into an aerated vertical flow reedbed. The two upstream ponds were used for additional balancing, and the downstream ponds provided further polishing treatment.

ARM also compensated to equalise the acid and alkali wash waters, ensuring the pH adjustment system received a more stable and manageable load.

The aerated reed bed system now provides Highland Spring's Blaen Twyni site with a more reliable wastewater treatment process, eliminating the need for costly daily effluent tankering. The upstream adjustments made by ARM also improved the balancing and optimisation of the pH adjustment system, making the entire water management process more robust and efficient.