Aerobic granular-based technology for water and energy recovery from municipal wastewater

Study on cultivation of aerobic granular sludge and its application in degrading lignin models in the sequencing batch biofilter granular reactor

In this study, three sequencing batch biofilter granular reactors (SBBGRs) were employed to treat model lignin wastewater containing different lignin models (2,6-dimethoxyphenol, 4-methoxyphenol, and vanillin). After 40 days of cultivation, uniform-shaped aerobic granular sludge (AGS) was successfully developed through nutrient supplementation with synthetic wastewater. During the acclimation stage, the chemical oxygen demand (COD) reduction efficiencies of the three reactors showed a trend of initial decreasing (5-20%) and then recovering to a high reduction efficiency (exceeding 90%) in a short period of time. During the stable operation stage, all three reactors achieved COD reduction efficiencies exceeding 90%. These findings indicated the cultivated AGS's robust resistance to changes in lignin models in water. UV-Vis spectra analysis confirmed the effective degradation of the three lignin models. Microbiological analysis showed that Proteobacteria and Bacteroidetes were always the dominant phyla. At the genus level, while Acinetobacter (15.46%) dominated in the inoculation sludge, Kapabacteriales (7.93%), SBR1031 (11.77%), and Chlorobium (25.37%) were dominant in the three reactors (for 2,6-dimethoxyphenol, 4-methoxyphenol, and vanillin) after degradation, respectively. These findings demonstrate that AGS cultured with SBBGR effectively degrades lignin models, with different dominant strains observed for various lignin models.

An innovative biofilter technology for reducing environmental spreading of emerging pollutants and odour emissions during municipal sewage treatment

Wastewater treatment plants (WWTPs) are known sources of contaminants of emerging concern (CECs) spreading into the environment, as well as, of unpleasant odors. CECs represent a potential hazard for human health and the environment being pharmaceutical or biologically active compounds and they are acquiring relevance in European directives. Similarly, the public concern about odour emissions from WWTPs is also increasing due to the decreasing distance between WWTP and residential areas. This study focuses on the effectiveness of the recently developed MULESL technology (MUch LEss SLudge; WO2019097463) in removing CECs and limiting odour emissions from WWTPs. MULESL technology has been developed for its ability to reduce up to 80% the sludge production from WWTPs. However, it is ought to evaluate if the benefits coming from sludge production reduction do not invalidate CECs removal or negatively affect odour emissions. Thus, the performances of a MULESL and a conventional WWTP (flow rate of 375 m³/d and 3600 m³/d, respectively) were compared while treating the same municipal sewage. Whereas both plants succeeded in removing the traditional gross parameters characterizing wastewaters (e.g. chemical oxygen demand, nitrogen), the MULESL was much more effective than the conventional one in terms of CECs removal for about 60% of the identified compounds showing, however, the same or lower effectiveness for about 30% and 10% of them, respectively. This result was attributed to the high sludge retention time and biomass concentration in the MULESL (enabling enrichment of slow growing microorganisms and forcing biomass to use unusual substrates, respectively), and to the biomass feature to grow in the form of biofilm and granules (favoring micropollutants absorption on biomass). Furthermore, odour impact analysis has shown that the MULESL was characterized by a much lower impact, i.e. 45% lower than that of primary and secondary treatments of the conventional WWTP.

A review on disinfection technologies for controlling the antibiotic resistance spread

The occurrence of antibiotic-resistant bacteria (ARB) in water bodies poses a sanitary and environmental risk. These ARB and other mobile genetic elements can be easily spread from hospital facilities, the point in which, for sure, they are more concentrated. For this reason, novel clean and efficient technologies are being developed for allowing to remove these ARB and other mobile genetic elements before their uncontrolled spread. In this paper, a review on the recent knowledge about the state of the art of the main disinfection technologies to control the antibiotic resistance spread from natural water, wastewater, and hospital wastewater (including urine matrices) is reported. These technologies involve not only conventional processes, but also the recent advances on advanced oxidation processes (AOPs), including electrochemical advanced oxidation processes (EAOPs). This review summarizes the state of the art on the applicability of these technologies and also focuses on the description of the disinfection mechanisms by each technology, highlighting the promising impact of EAOPs on the remediation of this important environmental and health problem.

Treating and reusing wastewater generated by the washing operations in the non-hazardous plastic solid waste recycling process: Advanced method vs. conventional method

The effectiveness of an advanced treatment of wastewater generated by non-hazardous plastic solid waste (PSW) washing, based on the Sequencing Batch Biofilter Granular Reactor (SBBGR), was assessed in terms of gross parameters, removal efficiencies and sludge production. The proposed treatment was also compared with the conventional treatment, which was based on primary and secondary treatments, using the activated sludge process, performed by Recuperi Pugliesi, a leading company in the plastic recycling industry located in Bari, Italy. The company produces low-density polyethylene (LDPE) regenerated granules from PSW used in agricultural and floricultural greenhouse activities and industrial packaging after a washing stage in the aqueous phase. The latter generates large volumes of wastewater, the conventional treatment of which is characterised by large quantities of sludge and the associated disposal problems. Under steady-state conditions, the SBBGR provided impressive removal efficiencies regarding the main gross parameters (over 90% for COD and TKN, over 99% for BOD₅, TSS, VSS and NH₃, and over 80% for TN) with a statistically better effluent quality than that of the conventional treatment. The SBBGR effluent quality was modelled in terms of washing water characteristics by using generalized additive models (GAMs). The SBBGR treatment was characterised by a specific sludge production five times lower than that of the conventional treatment (0.21 kg TSS vs. 1.0 kg TSS per m³ of wastewater treated). Compared with the conventional treatment, the proposed process showed a five-fold reduction in the cost of sludge disposal, which saved 50% of the operating cost.