Artificial neural networks (ANN) are increasingly being used in water treatment applications because of their ability to model complex systems. The present study proposed a framework to develop and validate ANNs for drinking water treatment and distribution system water quality applications. The framework was used to develop ANNs to identify the optimal ozone dose required for effective UV disinfection and to meet regulatory requirements for disinfection by products (DBP) in the distribution system. Treatment at a full-scale treatment plant was successfully modelled, with treated water UV transmittance as the output variable. ANNs could be used to identify operating setpoints that minimize operating costs for effective disinfection during drinking water treatment. However, because of the limited data available to train and validate the distribution system ANNs (i.e. n = 48; 15 years of quarterly measurements), these could not be used to reliably identify operating setpoints that also ensure compliance with DBP regulations.
Giving the current trend of recycling and reutilization residues, sludge reuse has become an environmental, social and economic necessity. A possible destination would be the utilization of sludge as part of cover layer in solid waste landfills. This paper aimed at investigating the geotechnical implications of the addition of domestic sanitized sewage sludge on clayey-silty sand. The sludge was sanitized with hydrated lime, in the proportion of 25% lime and 75% sludge, and held for 90 days in an agricultural greenhouse for its total stabilization. Then, geotechnical tests were conducted using pure soil, pure sanitized sewage sludge and mixtures of these two materials. Three mixtures were tested: 50% soil and 50% sludge, 66% soil and 33% sludge and 90% soil and 10% sludge. The results showed that the sanitized sludge is a coarse-grained material and, its Atterberg’s limits showed the lack of plasticity. Generally, the greater the sludge percentage in the mixture, the bigger the decrease on the shear strength parameters, it also leaves them lighter and more permeable. At the end, the conclusions were that the 10% sludge and 90% soil mixture has shown geotechnical characteristics that allow its utilization as daily and intermediate cover layers. The sludge and the 50% sludge mixture have shown geotechnical properties adequate for their utilization as component in draining sub-layer in final cover layer.
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