Investigation into a biosupplement for possible reduction of activated sludge production in a system with excess biological phosphorus removal

The availability and use of so-called "biosupplements" (or biological "catalysts") in wastewater treatment systems has increased significantly in recent years. The effectiveness of adding either live cultures of micro-organisms produced commercially (or enzyme products from such cultures) to systems which naturally develop mixed and complex populations of many different microorganisms (e.g. activated sludge) may be questioned. Comparatively few studies have been published in which the commercially produced cultures have been tested under controlled conditions. This study was aimed at conducting a controlled study of one "liquid live micro-organism" (LLMO) product in a nitrification-denitrification biological enhanced phosphorus removal (NDBEPR) activated sludge system. The product was marketed by the supplier for its ability to reduces sludge production in activated sludge systems. Using two parallel pilot-scale NDNEPR activated sludge systems operated in parallel under identical conditions, one with and one without the addition of the LLMO product, this study found no evidence to support the supplier's claim for the product, Two experiments were conducted: one in which the LLMO product was dosed in relatively large amounts without prior aerobic activation, and one in which activation was carried out aerobically for 24 to 36 h, as specified by the supplier. For both experiments, satisfactory mass balances for the systems could be shown, but no statistical difference in sludge production was observed, despite dosing at least ten times more product than that specified by the supplier for typical full-scale applications. Performance of the test and control systems was also virtually identical in all other respects.