Abstract
The provision of effective sanitation strategies has a significant impact on public health. However, the treatment of septic sludge still presents some challenges worldwide. Consequently, innovative technologies capable of an effective and efficient sludge treatment, mostly at a decentralized level, are in high demand to improve sanitation provision. To address this problem, this study evaluates a novel semi-decentralised mobile faecal sludge treatment system, the pilot-system for which consists of a combination of several individual processes including mechanical dewatering (MD), microwave (MW) drying, and membrane filtration (ultrafiltration [UF] and reverse osmosis [RO]). The system evaluation was carried out by treating raw, partially digested faecal sludge (FS) from septic tanks—hence, septic sludge (SS)—in the Jordan Valley, Jordan. The pilot-scale system exhibited an effective and flexible treatment performance for (i) sanitizing faecal sludge and related liquid streams (MW and UF); (ii) reducing the treated sludge mass (and sludge volume) (MD and MW); and (iii) producing a high-quality treated liquid stream ideal for water reclamation applications (UF and RO). The MD process removed approximately 99% of the initial SS water content. The MW drying system completely removed E. coli and dehydrated the dewatered sludge at low energy expenditures of 0.75 MJ kg−1 and 5.5 MJ kg−1, respectively. Such energy expenditures can be further reduced by approximately 40% by recovering energy in the condensate and burning the dried sludge, which can then be reused inland applications. The membrane filtration system (UF and RO) was able to produce high-quality treated water that is ideal for the water reuse applications that irrigation requires, as well as meeting the Jordanian standard 893/2006. In addition, the system can also be powered by renewable energy sources, such as photovoltaic energy. Therefore, this research demonstrates that the evaluated semi-decentralised mobile system is technically feasible for the in situ treatment of SS (sanitization and dehydration), while also being effective for simultaneously recovering valuable resources, such as energy, water, and nutrients.
Highlights
Implementing effective strategies for the prevention of contagious and potentially deadly diseases outbreaks is a priority for sanitation providers worldwide
Higher dry solid (DS) content have been reported in dry pit latrines compared to septic tanks or poorly draining leach pits, unless the water table in that particular region under evaluation is higher than the water level in the pit latrines and/or the flushing water from the toilets is discharged into the pit (Tayler 2018)
The particle destabilization of the sludge was carried out by dosing ferric chloride at 120 mg L −1 followed by rapid mixing, while the flocculation of the sludge was achieved by adding the polymer at a concentration of 50 mg L−1 followed by slow mixing
Summary
Implementing effective strategies for the prevention of contagious and potentially deadly diseases outbreaks is a priority for sanitation providers worldwide. Pit latrines and septic tanks are the most common alternatives worldwide for FS collection (Connor et al 2017; Thye et al 2011). Such collection facilities only enable the separation of faeces from human contact, so providing marginal treatment, if not properly treated at a later stage, such large amounts of FS only accumulate, creating a subsequent waste disposal problem. The dry solid (DS) concentrations lower than 5% are commonly reported for FS from septic tanks or from poorly draining leach pits (Tayler 2018). Sludge resource recovery activities can include the reuse of the sludge in agricultural applications, and the recovery of energy via co-combustion, among others (Kacprzak et al 2017)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
