i SewageSludgeCourse solids and bio solids accumulated in awastewater treatment process must be treated and disposed of in safe andeffective manner-creating sewage sludge. This material may be inadvertentlycontaminated with toxic organic and inorganic compounds.
However, sludge ashhas been investigated in the production of concrete. Results of several studieshave indicated the benefits of using sewage slag ash in concrete such ascompressive strength, freeze- thaw resistance and good hardening properties.Sewage sludge ash may be used as a mineral filler substitute or as a portion ofthe fine aggregate in hot mix asphalt paving.Course solids and bio solids accumulated in awastewater treatment process must be treated and disposed of in a safe andeffective manner-creating sewage sludge. This material may be inadvertentlycontaminated with toxic organic and inorganic compounds. However, sludge ashhas been investigated in the production of concrete.
Results of several studieshave indicated the benefits of using sewage slag ash in concrete such ascompressive strength, freeze- thaw resistance and good hardening properties.Sewage sludge ash may be used as a mineral filler substitute or as a portion ofthe fine aggregate in hot mix asphalt paving.Currently, clay is widely used to produce LWA andsludge can be used as a partial replacement for clay in the manufacture of LWA.Production of LWA from different types of sludge is considered to be a very satisfactoryeconomic and environmental alternative, since a starting material with no valuebecomes a product with important industrial application.Dried sludge can be converted into artificiallightweight aggregates, slags or bricks for the construction industry.Different properties and destinations for these materials depend on differentprocess variables and operating conditions. As of the use of dewatered sludge, the production ofPortland cement injecting the sludge directly into cement klins seems the mostappealing one. The major elements present in Portland cement are in fact Ca,Si, Al and Fe, which compare reasonably well to the elements present in sewagesludge.
Sludge can be exploited in construction industry inother different forms such as dried sludge powder or incinerated ash, as willbe seen in next chapter. Many technically feasible processes have been studiedand tested, but most of the techniques are not economically viable because of ahigh production cost, if compared to market price (Bonfiglioli, 2014).