Prince George Wastewater Treatment Centre
The City of Prince George's Landsdowne Road Wastewater Treatment Centre is one of the most cost
effective wastewater treatment facilities in British Columbia and includes both primary and secondary treatment.
The treated wastewater meets or exceeds all the Ministry of Environment's current requirements.
The Stage III B Upgrade includes an automated biofilter (trickling filter), solids-contact process for
secondary treatment. The process is energy-efficient, operator friendly and stable, and it produces a high
quality effluent.
Process
1. FLOW
Rags, sticks, plastics and other objects are removed, compressed and discharged to a waste hopper in
conjunction with grit from a grit separator system and skimmings from a skimmings dewatering screen.
2. PRIMARY SEDIMENTATION
Wastewater is held in a quiescent state for 2 to 7 hours. Lighter particles float and are skimmed off
to a skimmings well. Heavy particles sink and are raked to biosolids sumps where they are pumped to the
anaerobic digesters.
3. BIOFILTERS
The settled wastewater is distributed over plastic media plates where dissolved organics are
absorbed on growing biomass, and particles are filtered out or trapped. A cloudy trickling filter effluent
is then pumped to the solids contact basin.
Distribution Pipes Above Biofilters
4. SOLIDS CONTACT TANK & SECONDARY CLARIFIERS
The cloudy trickling filter effluent is combined with settled solids from the clarifiers and mixed in the
solids contact tank before settling is again provided in the clarifiers. The now clear water flows to a final
disinfection step. Some of the settled solids are returned to be remixed with the biofilter effluent, and the
remainder is pumped to the inlet of the grit tanks.
Secondary Clarifier
5. CHLORINE CONTACT
The plant has facilities for effluent disinfection using gaseous chlorine and sulphur dioxide. However,
these facilities are not currently being used since the plant is achieving suitable effluent coliform counts,
without the use of disinfection products.
6. BIOSOLIDS STABILIZATION
The biosolids from the primary sedimentation tanks and the waste biological solids from the
secondary clarifiers are pumped to the anaerobic digesters. Treatment is conducted in two stages,
producing a slurry which is stabilized and greatly reduced in organic content. Methane gas is also produced as a
by-product. This gas is combusted in the Treatment Centre's boilers for biosolids and space heating.
7. SOLIDS DEWATERING
Once digested, the stabilized biosolids are dewatered to a dry cake by belt filter presses.
8. BIOSOLIDS STORAGE
The dewatered biosolids are stored on site and routinely delivered to farms in the Prince George area
for use as a nitrogen rich soil conditioner.
The City of Prince George Lansdowne Road Wastewater Treatment Centre is classified
as a Level IV plant.
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