Solar sludge drying: 35.000 inhabitants with total sludge for sewage of 5,000m³/d
This solar sludge drying system is the largest reed bet based drying system in Rheinland Pfalz / Germany. It is drying the sludge from a public sewage treatment system Simmern. The sludge treatment has been done previously via two silos where the sludge was statically thickened and mechanically dried via a filter press. The dried sludge was then temporarily stored and afterwards used in the farming sector.
Based on economical reasons as well as long term waste treatment security the relevant body "Abwasserzweckverband Simmern" has decided to build a solar powered sludge drying system based on reed bed principles.
The design and monitoring contract was awarded in November 2004. The actual approval to build this system was given in May 2006.
In June 2006 the construction work has started and finished in March 2007. The first sludge was directed onto the reedbed already at the same month.
The key elements of this system are:
- Construction of two additional sludge silos with 1,500m³ to store the sludge during the winter months.
- Construction of sludge pumping station to transport the sludge from the sewage system to the reed bed.
- Construction of a 620m long pressurized sludge pipe and a pipe transporting the effluent water from the reed bed back to the sewage treatment plant. The pipes were laid under a dual carriage way (B50) and through a small river.
- Construction of the reedbed system with 19,000m² surface and around 50,200m³ usable volume
- Interconnect the new monitoring and control system with the existing sewage plant electronic controls.
- The construction costs for these actvities have been around ? 3,2 m
- Description of overall functioning
- first sludge, pumping station, sludge silos
1. The sludge is pumped for the sewage treatment plant to the reed bed
2. Individual controllable distribution lines bring the sludge evenly over the reed bed
3. To protect ground water the reed bed is sealed watertight with plastic.
4. The sludge has a dry matter of 2-2.5%. Therefore it contains 98% water which flows through via the plants into the ground, is consumed by the plants or evaporates.
5. The effluent of the reed bed is collected and pumped back to the sewage treatment plant
6. Since the sludge stays for almost 25 years in this reedbed it gets mineralised with the help of the plants and becomes similar to earth/humus material. This can be used directly a gardening or landscaping material.
