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The first case of Coronavirus Disease 2019 (COVID-19), which is caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), in Europe was officially confirmed in February 2020. On 11 March 2020, after thousands of deaths from this disease had been reported worldwide, the WHO changed their classification of COVID-19 from a public health emergency of international concern to a pandemic. The SARS-CoV-2 virus has been shown to be much more resistant to environmental degradation than other coated viruses. Several studies have shown that environmental conditions can influence its viability and infectivity. This review summarizes current knowledge on the transmission pathways of the novel coronavirus, and directs attention towards potentially underestimated factors that affect its propagation, notably indoor spread and outdoor risk sources. The contributions of significant indoor factors such as ventilation systems to the spread of this virus need to be carefully ascertained. Outdoor risk sources such as aerosolized particles emitted during wastewater treatment and particulate matter (PM), both of which may act as virus carriers, should be examined as well. This study shows the influence of certain underestimated factors on the environmental behavior and survival of the SARS-CoV-2 virus. These aspects of coronavirus propagation need to be accounted for when devising actions to limit not only the current pandemic but also future outbreaks. Graphic abstract

Ultrasonication with water recirculation slightly enhanced the removal of toluene compared to water recirculation alone due to conjunction of pyrolysis and hydroxyl radical oxidation with absorption. On the other hand, the addition of ozone with ultrasonication decreased the removal efficiency due to scavenging of hydroxyl radicals. The reaction rate for ozone and OH radicals produced during the US process was faster compared to the rate for ozone and toluene.

This paper presents self-forming dynamic membrane (SFDM) process as a promising alternative to membrane technology. A stable dynamic membrane (DM) is mainly composed of gel layer and cake layer which are responsible for filtration and biodegradation. An understanding of the formation mechanism and impact of operating conditions, support mesh, sludge properties and configuration on the formation, and characteristics of the dynamic membrane is essential to optimize the efficiency and reduce fouling propensity of this technology. The paper thus aims to promote its applicability on wastewater treatment. Review of the influence of mesh support properties, different operating conditions and sludge properties on SFDM performance, and cost comparison between MBR and SFDMBR technologies.

This paper focused on the combination of membrane ultrafiltration, adsorption and ultrasound processes in one hybrid process called USAMe for improving membrane wastewater treatment performance and membrane fouling control. Different tests were conducted at different ultrasound frequencies and recycle ratio. Improved permeate quality in the USAMe process. Membrane fouling reduction with the combined application of ultrasound and activated carbon. Influence of ultrasound frequency, membrane flux and recycle ratio on treatment performance.

Membrane bioreactor (MBR) is a reliable and promising technology for wastewater treatment and reuse. However, since membrane fouling and energy consumption still remain operational obstacles and challenges for the widespread application of the MBR technology, research studies for fouling control are still underway. Recently, among different integrated approaches for membrane fouling mitigation, the combinations of MBRs with electrochemical processes (eMBR/electro MBR) or with moving bed biofilm reactor (MBBR) have been adopted as alternative technological methods. In the present study, the performance of an electro moving bed membrane bioreactor (eMB-MBR), in terms of treatment efficiency and fouling formation, was investigated as a novel integrated process which combines an electro MBR with a moving bed membrane bioreactor (MB-MBR). An intermittent voltage gradient of 3 V/cm was applied between two electrodes immersed around a membrane module inside the bioreactor filled with carriers at 30% filling ratio. A MB-MBR was operated as a control test. The integration of electrochemical processes into the MB-MBR improved the treatment performance especially in terms of nutrient removal, with an enhancement of orthophosphate (PO4-P) and ammonia nitrogen (NH4-N) removal efficiencies up to 55.0% and 98.7%. The filtration cycles were extended in the eMB-MBR with a reduction of membrane fouling rate of around 60% and of membrane fouling precursors respect to the control test. The results obtained showed the synergic effect of the combined process. Hence, the eMB-MBR process represents a novel exciting technology which is deemed possible for wastewater treatment.