Temporary treatment systems for a park in Stratford

The above ground units were purchased by the contractor Natta Building Company for the 2000 temporary workers/staff due to a lengthy construction period; the portable units provided a complete wastewater treatment process capable of achieving the following consent standard:

• Peak flow to treatment: 10.5l/s
• Designed consent standard: 20 mg/l
• BOD, 30 mg/l TSS & 10 mg/l
• NH4Maximum incoming BOD: 380 mg/l
• Maximum incoming NH4: 50 mg/l

The raw sewage influent will be pumped to the inlet of the lamella plate primary settlement tank (LPPST) where it is anticipated 30% of the BOD load will settle out. After primary settlement the outlet flow will leave the LPPST via multiple outlet connections which effectively split the flow into equal streams. The LPPST is equipped with baffles to prevent any floating scum entering the biological phase of the treatment. Sludge is periodically transferred to a separate sludge storage tank utilising an actuated valve on the sludge outlet point.

After primary settlement the flows will split (under full loading conditions) and flow under gravity to one of the SAF bio-treatment streams consisting of multiple T300 SAF biological treatment tanks, and the two streams re-combine to flow into one single T750 unit. These tanks are of the submerged bed aerated filter type (SAF) and are each split into several chambers each filled with high voidage plastic media. Whilst passing through these chambers both carbonaceous and nitrifying processes take place. Air to oxidise the influent and to scour excess biomass from the filter media is introduced continuously below each chamber by a series of diffusers. Each diffuser is capable of being removed for maintenance without the necessity to shut down the plant.