Integrating alum sludge with waste-activated sludge in co-conditioning and dewatering: a case study of a city in south France

Abstract

The unique geographical location of waterworks and wastewater treatment plant (WWTP) in Graulhet (France) profited the environmental resource integration and "Circular Economy." Alum sludge from a local waterworks was introduced to co-conditioning and dewatering with waste-activated sludge from a nearby WWTP to examine the role of the alum sludge in improving the dewaterability of the mixed sludge. Experiments demonstrated that the optimal mixing ratio was 1:1 (waste-activated sludge/alum sludge, v/v). Alum sludge has been shown to beneficially enhance mixed sludge dewaterability, by decreasing both the specific resistance to filtration (SRF) and the capillary suction time (CST). Moreover, the optimal polymer (Sueprfloc-492HMW) dose for the mixed sludge (mix ratio 1:1) was 200mg/l, highlighting a huge savings (14 times) in polymer addition without alum sludge involvement. In addition, cost-effective analysis of its potential full-scale application has demonstrated that the initial investment could be returned in 11years. The co-conditioning and dewatering strategy can be viewed as a "win-win" strategy for the Graulhet, France water and wastewater industry.

Valorization of undervalued aluminum-based waterworks sludge waste for the science of “The 5 Rs’ criteria”

“…Based on the available literature cited, the physicochemical characteristics and geotechnical data range of the alum sludge are displayed in Table 1. Such data reveal a wide range in most characteristics this is mainly due to the different sources of alum sludge waste, which is based on the source of watercourse water (Babatunde et al 2007;Ippolito et al 2011;Ren et al 2020). Moreover, alum sludge properties are highly characterized by the variation in the coagulant applied in the water treatment plant.…”

Application of Alum Sludge in Wastewater Treatment Processes: “Science” of Reuse and Reclamation Pathways

“…Taylor and Elliott [38] reported the co-conditioning and dewatering of AlS with sewage sludge, which reduced the amount of polymer dosage so that the total cost of sludge treatment was decreased. More recently, Ren et al [39] demonstrated the use of a French liquid AlS in co-conditioning and dewatering with sewage sludge from a nearby WWTP. An integrated, cost-effective evaluation of process capabilities was also conducted and the benefit of the joint conditioning and dewatering was obvious, indicating that it is capable of being implemented in practice.…”

Waterworks Sludge: An Underrated Material for Beneficial Reuse in Water and Environmental Engineering

“…The role of the WTS that could strengthen sewage sludge conditioning lies in the strong coagulation elements of Al 3+ and Fe 3+ [59]. The process is to form the co-conditioning and dewatering of WTS and sewage sludge [60,61]. Yang et al [60] conducted a study on the co-conditioning and dewatering of an Irish AlS with wastewater sludge in Dublin, Ireland and demonstrated that the AlS could improve sewage sludge dewaterability.…”

“…Taylor and Elliott [62] reported co-conditioning and dewatering of AlS with sewage sludge which reduced the amount of polymer dosage so that the total cost of sludge treatment was decreased. More recently, Ren et al [61] demonstrated the use of a liquid AlS obtained from Graulhet waterworks in South France in co-conditioning and dewatering with sewerage sludge from a nearby WWTP. By considering the P concentration in the supernatant as well as the treatment capacity of Graulhet WWTP, the optimal mixing ratio of sewerage sludge and AlS in v/v was 1:1.…”

“…From now, it is necessary to adopt/focus on 5R principles (Reduce, Reprocess, Reuse, Recycle and Recover) of waste management for sustainable development. It is crucial to identify viable management options for WTS, particularly where WTS can be effectively utilized in an environmentally acceptable and sustainable manner [61]. To date, there are four broad categories of beneficial WTS reuse routes.…”