PONDUS® TCHP reduces sludge viscosity, enhances biogas production and improves sludge dewaterability.

PONDUS® TCHP, an alkaline process, utilizes low grade heat (60 °C to 70 °C) and sodium hydroxide for sludge hydrolysis. A typical PONDUS® TCHP plant consists of a hydrolysis reactor, hot water heat exchanger, chemical dosing station, pumps, instrumentation and controls. All components are standard aggregates used on WWTPs.

PONDUS® design allows it to operate the system under atmospheric pressure conditions without involving a pressurized vessel.

This is how PONDUS® TCHP works:

[1] Thickened waste activated sludge (WAS) is mixed with a small dose of [2] caustic soda.

[3] Sludge is heated in a loop through a high-efficiency heat exchanger.

[4] Sludge is fed into PONDUS® reactor and goes through hydrolysis. After the hydrolysis process, sludge leaves the reactor close to a neutral pH level and the absorbed thermal energy is almost entirely used in the anaerobic digester [6].

[5] Thickened primary sludge is mixed with hot hydrolysed sludge achieving an ideal mesophilic temperature and then pumped into the digester [6].

If needed, additional heat can be provided to the digester through a [7] heat exchanger.

• Reduced sludge quantity
• Reduced viscosity of thickened WAS up to 80%
• Reduced anaerobic digestion volume up to 50%
• Improved biosolids dewatering up to 5%
• Increased biogas production up to 30%
• Reduced polymer consumption at dewatering up to 20%
• Reduced digester foaming

• Simple operation requires little daily plant supervision
• Fully automatic process runs 24/7
• 99% uptime; minimal estimated downtime for maintenance and repairs
• Simple technology using standard industrial control system equipment
• Compact; small footprint solution for all sized plants
• Almost thermal energy neutral
• Low electrical energy consumption

This patented solution uses steam for heating up the sludge, thus eliminating dependence on the heat transfer rate of heat exchangers. However, with this system, the entire sludge line remains under atmospheric pressure conditions.

The feed water [4] is converted into low-pressure saturated steam in a steam generator [5] and injected into the sludge [6]. The heated waste activated sludge [1] is mixed with caustic soda [2] [3]. In the reactor [7] the hydrolysis process takes place. The pH-neutral, hydrolysed warm sludge [8] is mixed with the cold primary sludge [9] for cooling [10] and pumped together to digestion [11].

The PONDUS® hygienisation plants are designed for quasi-continuous operation. In order to achieve hygienisation, the entire quantity of sludge must be treated.

The three reactors [3a, b, c] are alternately charged [1, 2]. The first reactor is fed with heated sludge, in the second tank the hygienisation and hydrolysis processes take place, while the third reactor is drained.

Heat recovery [W1] can be easily integrated. Further cooling [W7] of the hygienized sludge prior to digestion may be required.