Programme outcome
October 2014–January 2015
Biological-stage recovery · November 2014–January 2015
Initial situation
The plant had a design capacity of 120,000 m³/day and an actual flow of approximately 90,000 m³/day. The analytical summary describes disrupted biomass, recirculation of dead sludge and inhibitory influent components. An October effluent sample recorded BOD₅ of 90 mg/L and suspended solids of 204 mg/L.
Actions taken
The programme began on 15 November 2014, with BIOFOX dosed into the receiving/equalisation chamber. An intensive initial stage was followed by gradual dose reduction and maintenance dosing. The source programme applies to this site.
Application results
The analytical team concluded that biomass development and nitrification had recovered over two months. A sample taken after biological treatment on 14 January 2015 recorded BOD₅ of 25 mg/L, suspended solids of 15 mg/L and ammonium of 11.87 mg/L. The conclusion reports process recovery and reduced nuisance odours; discharge limits had not yet been achieved at that stage.
Site and period
The October and November samples relate to the final discharge; the January sample relates to the biological-treatment outlet. Sampling types also differed: a shift composite and grab samples. The stages are therefore shown separately without calculating a single reduction percentage. By January the process had recovered, while reaching discharge limits remained the next programme objective.
Documentary basis
Analytical summary dated 1 February 2015: baseline and programme on page 1; reports 132 and 128 on page 2; report 57T and photographs on page 3; conclusion on page 4. Sampling points and dates are identified separately.