Relationship between Sludge Content and Disposal Strategies


The beneficiation of sludge is encouraged through the South African Wastewater Sludge Guidelines to ensure sustainable sludge management. However, not all the sludge produced in South Africa is of such quality that it can be used beneficially, which leaves disposal as the only feasible option.


Different from the water content in conventional soil, sludge contains a large amount of organic matter, and its water exists in four types: interstitial water, capillary bound water, surface adsorbed water and internal water.


The residue that accumulates in sewage treatment plants is called sludge (or biosolids). Sewage sludge is the solid, semisolid, or slurry residual material that is produced as a by-product of wastewater treatment processes. This residue is commonly classified as primary and secondary sludge. Sludge is mainly composed of dry solids and moisture.


Sludge treatment and disposal are two different concepts. Sludge disposal is defined as: “The process of absorbing sludge after treatment, generally including land use, landfill, building material utilization and incineration.” The volume of sludge produced in a wastewater treatment plant is about 1% (dewatered sludge is 0.5‰) of the volume of influent wastewater to be treated. To manage WWTPs effectively and efficiently, it’s important to reduce the amount of sludge released from the systems, or feasible, but sometimes cost and CO2 emission intensive disposal schemes such as land use, sanitary landfill, building materials utilization, incineration, etc. must be considered.


The Membrane Aerated Biofilm Reactor MABR can produce up to 50% less sludge compared to conventional activated sludge systems. The biomass in an MABR system is attached to the spirally wound membrane surface, leaving a far lower concentration of suspended solids in the bulk liquid. Furthermore, extracting useful elements from the sludge, most will agree that the utilizing useful elements such as carbon and nutrients in the sludge, especially for reuse in agricultural practices, is one of the most viable management solutions for South Africa.


We have implemented prime solutions that are designed to ease the cost of sludge disposal and chemical use - speak to our professional staff to hear more about our revolutionary systems.





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