Treatment Of Sludge And Digestion Of Solids

Wastewater treatment processes whether physic-chemical and/or biological, involve the production of sludge (solid), which, to be used and/or disposed of, must follow a specific treatment to mitigate the environmental impact and comply with current regulations. Alternatively, the sludge may be used to generate electric or thermal energy.

Sludge Thickening

Sludge thickening is usually the first stage of the treatment to reduce water content and minimize energy consumption in transportation. Consequently, depending on the technology used, sludge with solid concentrations is obtained; the goal in this stage is to deliver sludge between 2.5% and 6% solid.
According to operating conditions, Ecopreneur may provide customized or standard equipment such as:

Rotary Drum

Thickening Table

Thickening Bridge

Dissolved Air Flotation (DAF)

Sludge Dewatering

After thickening, usually the subsequent stage involves dewatering the sludge to eliminate water run-off and to obtain solids that will have between 75% and 82% humidity. 

Press Filter 

Belt Filter

Screw Press and Centrifuges (Decanter) 

Dosing Systems

Thickening and dewatering processes are supported with a dosing of chemical flocculating agents to strengthen the solids, which are under mechanical stress, allowing the separation of water without breaking the formed flocs so that solids are retained in the filter. 

Polymer dose Systems (powder and emulsion) 

Sludge Liming

This referrers to applying lime to reduce the biological activity of the sludge water in order to reduce the attraction potential of vectors.

The sludge sanitation level from sewage treatment plants (WWTP) should be reached according to DS No. 04/2009 “Regulations for Management of Sludge Generated in Sewage Treatment Plants”.

Ecopreneur provides dosing lime equipment before or after dewatering treatment.

Lime Dosing Hopper 

Dewatered Sludge-Lime Mixing Screw and Screws Conveyors

Cal Silos and BigBag Hoppers 

Solar Drying

There is the option of drying sludge by taking advantage of solar energy using a proprietary system, Thermo-system® (Germany), to reach sludge quality type A or B according to SD 04/2009 without adding lime or higher levels of dryness than those conventionally reached with exclusive dewatering. Thermo-system® uses solar radiation energy, controlling drying mechanisms and managing atmospheric variables to evaporate water from sludge to produce up to 90% dried solids.


Solids Biodigestion

The anaerobic process comprises harnessing biological activity in the sludge (generated in production processes or coming from wastewater treatment) and its own organic content to transform the mass into biogas, consequently obtaining a stabilized and mineralized sludge at the same time.

Sludge digestion includes hydrolysis, acidogenesis and methanogenesis processes, which are carried out under anaerobic conditions in reactors sized and equipped for its application. The biological process may be carried out at mesophilic (about 35°C) or thermophilic (about 55°C) temperature conditions, depending on the sludge features, target sludge mineralization and available energy.

Biogas with a high content of methane (CH4) and carbon dioxide (CO2) can be treated to burn and generate electric and/or thermal energy later. This energy can be applied to the treatment units, generating a self-sustaining process.

Anaerobic Solids Digesters


Biogas treatment and energy cogeneration


Mobile Dewatering–Liming Process

Sludge dewatering from wastewater treatment plants can be carried out as a mobile or stationary process. Ecopreneur has already implemented these and can be based on a filter press, filter band, centrifuge or screw press.

Dehydrated Mobile Filter Band – ESSBIO S.A.