A. INSTALLATION GUIDE 2. OPERATING PRINCIPLE OF THE MONOBLOCK STP
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Installation and User guide – MONOBLOCK Systems – 06-12-2016
2. Operating principle of a MONOBLOCK Treatment Plant
The MONOBLOCK system is composed of 2 compartments. Initially the raw sewage enters the first
compartment to provide separation and the breakdown of organic solids (Primary Treatment). The
sewage then passes through an effluent filter before discharging into the secondary compartment
which incorporates the well proven aerobic digestion process (Secondary Treatment) and filtration
process (Tertiary Treatment).
2.1 PRIMARY COMPARTMENT: OPERATING PRINCIPLE
The effluent (domestic wastewater composed of black water: origin toilets – and grey water: origin
kitchen, bathroom, laundry) enter the primary compartment of the MONOBLOCK system. This
primary compartment carries out the first basic phase of wastewater treatment, that is separation of
solids and fats by flotation (formation of a grease layer) and by clarification (the suspended solids
sink to the bottom of the tank by natural settlement). Separated solids building up at the bottom of
the primary compartment are called “primary sludge”. This sludge breaks down in time by anaerobic
digestion.
The primary compartment is equipped with an efficient effluent filter. This filter holds back
remaining suspended solids, fats and other floating matter which enables a higher quality of pre-
treatment.
2.2 SECONDARY COMPARTMENT: OPERATING PRINCIPLE
The well-proven BIOROCK biological purification process takes place in the second compartment of
the MONOBLOCK system. The BIOROCK media is used as a carrier material allowing colonization of
the necessary bacteria, a process which is essential for the effective treatment of domestic
wastewater.
The MONOBLOCK system consists of three biological filtration stages and one aeration stage.
(See
Appendice 1.5 : Détail of BIOROCK media layer)
M
The pre-treated water is spread over the surface of the first layer of BIOROCK media by an effluent
distribution system and penetrates into the media for purification.
M
The effluent flows via gravity through a ventilated area, mixing oxygen with the effluent prior to
the secondary filter stage. Efficient ventilation throughout the treatment plant is essential for
maximized performance.
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A second section of the compartment contains a second media bed providing further
treatment
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Finally, the lower section of the tank contains a third media bed providing final treatment.
See Ch. B/3.2 for weight details of each BIOROCK media layer
The treated water discharging from the unit must flow by gravity to the next stage or a discharge point.
We advise to avoid stagnant treated effluent at the discharge point. Make sure the discharge pipe is
equipped to avoid small animals entering the system.
Each MONOBLOCK system should be vented independently and equipped with its own ventilator (wind
driven or electrical if necessary).
(See appendix 2.4: Ventilation scheme).
