Sludge Dewatering and Mineralization in Sludge Treatment Reed Beds

Abstract

Sludge Treatment Reed Beds (STRBs) are widely used in Northern Europe to dewater and mineralize surplus sludge from activated sludge systems used to treat urban domestic sewage. STRBs are low-technology, energy-efficient, and do not require addition of chemicals. They dewater and stabilize the sludge and produce a final product that can be safely used as a fertilizer for agricultural crops. Long-term sludge reduction takes place in the reed beds due to dewatering and mineralization of the organic matter in the sludge. Although, in theory, a simple technique relying largely on natural processes, experience has shown that it is very important to understand and respect the basic design and operation requirements of STRBs. This paper describes the basic design and operation requirements of STRBs, with special focus on pivotal requirements to respect in order to secure proper functioning. Also, the paper summarizes performance experience concerning final dry matter content, degree of mineralization, emission of greenhouse gases, and degradation of micro-pollutants in STRBs. There are still a number of outstanding issues that are not fully understood, particularly in relation to the importance of the sludge quality for the dewatering in an STRB. Therefore, extreme care should be taken when attempting to extrapolate the use of STRBs to applications and regions outside of their 'normal' and documented area of application.

Dewatering and Treatment of Septage Using Vertical Flow Constructed Wetlands

“…It should also be noted that the sludge deposit is required to be disposed when its accumulation meets the capacity of the wetland bed. This highlights another purpose of septage treatment: stabilisation of the volatile organic matter and nutrient remaining in the sludge deposit to make sure that it can be safely disposed [8]. The degradation of these pollutants, so-called mineralisation, depends on the microbial activities, which mostly occur during the resting period.…”

“…The presence of vegetation is found to be advantageous in enhancing the dewatering efficiency [7]. The remaining organic matter in the dewatered septage at the wetland surface are stabilised through microbial decomposition, which is the so-called mineralisation [8]. In order to optimise the dewatering efficiency, the control of solids loading is typically employed as the feeding strategy.…”

Treatment of Septic Tank Sludge in a Vertical Flow Constructed Wetland System

“…For Brix (2014), the fact of not having plants across the bed surface is one of the most common problems observed in CW. The plants reached a maximum height of 83.1 cm.…”

Constructed Wetlands for Water Treatment: New Developments

“…Brix H. [9] presents an overview of the use of sludge treatment reed beds (STRBs) for sludge dewatering and mineralization. The design and operation requirements of STRBs are described, and their performance is summarized for final dry matter content, degree of mineralization, emission of greenhouse gases, and degradation of micro-pollutants.…”

“…The design and operation requirements of STRBs are described, and their performance is summarized for final dry matter content, degree of mineralization, emission of greenhouse gases, and degradation of micro-pollutants. Although STRB application has been limited to northern Europe, it is identified as a technology with application potential in other climatic regions, as well as for several types of sludge [9].…”