Extending disposal route of dewatered sewage sludge produced from the new wastewater treatment plant in Nicosia toward sustainable building materials

Abstract

Due to urban development worldwide, disposing sewage sludge (SS) has become a major concern for many countries. SS produced from the New Waste Water Treatment Plant (NWWTP) in Nicosia has not been used for soil application as it was planned since late 2013 due to absence of legislations regarding this route. This issue has been and still a major concern for of Nicosia Turkish Municipality and its society for many years. This study investigates the potential use of SS as construction material by producing an artificial lightweight aggregate (ALWA) and cement replacement material. Fine dry sludge (FDS) and sewage sludge ash (SSA) were used as raw materials for ALWA production. FDS was incinerated at 850 °C for 1 and 2 h to produce SSA1 and SSA2, respectively. Both SSA1 and SSA2 were mixed separately with FDS in different proportions and incinerated at 1100 °C to produce lightweight aggregate AG1 and AG2, respectively. Potential use of SSA1 and SSA2 as cement replacement materials was assessed by measuring the Pozzolanic activity of both ashes throughout physical and chemical tests. It was found out that increasing amount of FDS reduced specific gravity of AG1 and AG2, while increasing amount SSA in the mix improved the surface texture and increased the specific gravity of both AG1 and AG2. Results also indicated that both SSA1 and SSA2 have Pozzolanic properties based in all tests performed. Therefore, using sewage sludge produced from the NWWTP in Nicosia as a sustainable construction material is potential and this could extend the disposal route of the sludge and resolve the accumulation problem in Nicosia.