Capable of receiving a flow equivalent to 217.7 million liters in 24 hours, the Jundiaí station combines eight lagoons, microorganisms, diffused air, and centrifuges to reduce the organic load and direct thousands of tons of sludge to composting every month.
In the interior of São Paulo, the Jundiaí Sewage Treatment Plant operates a structure capable of receiving 2,520 liters per second during peak periods, a volume equivalent to 217.7 million liters over 24 hours at this level.
Announced by the Jundiaí Sanitation Company, this capacity shows the scale of a system that receives effluents from homes, businesses, and industries, reduces most of the organic load, and directs thousands of tons of sludge for reuse.
To prevent sewage from reaching the Jundiaí River with the same concentration of residues and organic matter found at the entrance, the operation brings together physical and biological stages organized in a continuous sequence of separation, degradation, and control.
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According to the Jundiaí Sanitation Company, the unit has a regular capacity of 1,530 liters per second, maintains an average flow of approximately 1,100 liters per second, and can reach 2,520 liters per second when the intake reaches peak levels.
Between the operational average and the maximum limit, the difference helps explain the use of the expression “swallows” in the title, as the station needs to absorb significant volume variations without interrupting the functioning of the subsequent stages.
Even under greater pressure, the flow must continue passing through the removal of trash, sand, and pollutants, through the activity of microorganisms, and through the separation of sludge before the treated effluent is released to return to the environment.
Sewage treatment begins with the removal of trash and sand
Right at the entrance, grates form the first barrier and retain solid materials transported by the network, such as plastics, cloths, and other objects that do not belong in the biological process and could compromise pumps, pipes, and equipment.
After this initial screening, submersible pumps raise the sewage to the following units, while measuring instruments continuously monitor the received flow and provide necessary data to adjust the station’s operation to volume changes.
Before the start of the biological stage, the sand that arrives mixed with the sewage also needs to be removed, because its heavier particles can accumulate in the equipment and occupy areas intended for the treatment of organic matter.
Through decantation, the movement of the water slows down and allows this mineral material to settle at the bottom, preparing the flow to advance without carrying residues capable of reducing the efficiency of subsequent structures.
Aeration ponds use microorganisms and diffuse air
At the center of the operation are the aeration ponds, where bacteria degrade the organic matter present in the sewage through an aerobic biological process that depends on the continuous supply of oxygen.
Instead of large agitators installed on the surface, the unit uses floating membrane diffusers and thousands of points responsible for releasing small air bubbles, distributed to sustain the activity of microorganisms within the ponds.
As these bubbles rise through the water, they provide oxygen and keep the biological flocs suspended, clusters of microorganisms that consume part of the organic matter responsible for the pollution found in the sewage received by the station.
In this way, the process accelerates in a controlled manner a decomposition that also occurs naturally in watercourses, but without the same concentration of equipment, available oxygen, and operational monitoring maintained within the facility.
According to the operator, Jundiaí hosts the first Brazilian station to employ diffuse air in ponds, a system that distributes small bubbles from the bottom and avoids the formation of aerosols associated with the use of large mixers.
In total, the structure comprises three aeration ponds and five decantation ponds, forming eight units connected to the sewage path and responsible for maintaining the oxygenation and separation phases within the planned sequence.
Decantation separates the sludge from the treated water
Once aeration is completed, the flow moves to decantation ponds that do not receive the same agitation, a necessary condition for the biological flocs to slowly descend and accumulate at the bottom of the structures, forming the sludge.
At the top, remains water with a much smaller portion of the initial pollution, which can advance to the receiving body as long as it remains within the operational conditions established for the treatment station.
Informed by the Companhia Saneamento de Jundiaí, the process efficiency reaches 96% in the removal of organic load, an indicator that measures the reduction of biodegradable matter present in the sewage after passing through the biological stages.
This percentage represents the treatment performance, but does not mean that the effluent becomes potable water, as its destination is environmental return, while the separated sludge follows its own route within the facility.
Centrifuges prepare the sludge for composting
Removed from the bottom of the lagoons by dredging, the sludge is sent to the centrifuges, equipment whose rotation separates part of the water still present in the solids and produces a dehydrated material more suitable for transport.
According to the operator, about 3,500 tons of dehydrated sludge are sent monthly for composting, a stage in which the waste is mixed with organic materials and prepared to undergo controlled transformation.
During composting, the sludge receives shredded urban prunings, sugarcane bagasse, and eucalyptus bark, a combination that favors the activity of microorganisms and allows the development of the necessary conditions for the treatment of the compound.
The temperature of the material exceeds 55 degrees Celsius, according to Companhia Saneamento de Jundiaí, promoting sanitation and the elimination of phytopathogens before the resulting product is destined for different forms of use.
Classified by the operator as composite organic fertilizer, the product is registered with the Ministry of Agriculture and can be used in crops such as coffee, sugarcane, soybeans, fruits, and forest species.
In addition to agricultural applications, the material can also be used for lawns and landscaping projects, provided that the control of the industrial sewage received keeps the composition of the sludge suitable for the intended reuse.
Station treats large-scale organic load
More than the volume of water, the organic load received helps to size the scale of the operation because it represents the amount of biodegradable matter that needs to be processed by microorganisms during treatment.
Companhia Saneamento de Jundiaí reports the capacity to treat up to 90 tons of biochemical oxygen demand per day, a load equivalent to that produced by a population of approximately 1.67 million inhabitants.
In this calculation, in addition to residential contribution, effluents linked to industrial activities connected to the system are included, responsible for increasing the amount of organic matter that arrives daily at the station and needs to be degraded.
Energy consumption follows this scale, as the unit uses about 1,900 megawatt-hours per month to pump the sewage, supply air to the lagoons, and operate the equipment used in separation.
Among these activities, aeration plays a central role, as microorganisms depend on the continuously distributed oxygen to keep the biological process active and reduce the organic load present in the sewage.
Sewage collection reaches almost all of Jundiaí
Created to treat the municipality’s sewage, the Jundiaí WWTP incorporated sludge composting as a permanent part of the process, connecting effluent treatment to the reuse of a portion of the generated waste.
According to the Jundiaí Sanitation Company, 98% of the sewage produced in the city is collected, and 99% of this volume goes to the station, where it undergoes treatment stages and receives appropriate disposal.
After disappearing down the drain, the water travels a path formed by grates, pumps, decantation, oxygen, bacteria, centrifuges, and operational control before returning to the environment with a significantly lower organic load.
How many people imagine that the sewage of an inland city travels through eight lagoons, undergoes the action of thousands of microorganisms, and can still end up converted into fertilizer used in agriculture?
