One of the main advantages of controlled struvite formation in digested sludge is an improvement in dewaterability of the digested sludge, which eventually leads to lower volumes of dewatered sludge that need to be transported. The effects of the control parameters for struvite formation, magnesium concentration and pH, on digested sludge dewaterability were investigated and are discussed in relation to the efficiency of struvite formation. Laboratory experiments with digested activated sludge were performed in a 20 L batch reactor. CO2 was stripped from the digested sludge using a bubble aerator and magnesium chloride was added to induce struvite formation. The dewaterability of the sludge was determined by gravity filtration tests. In the experiments, either the pH or the molar magnesium to phosphate ratio (Mg:PO4) was varied. The results confirm improved sludge dewaterability after struvite formation. Magnesium to phosphate ratios above 1.0 mol/mol did not further improve dewaterability. The addition of magnesium did not prevent the need for polymer addition for sludge dewatering. An increase in pH led to a deterioration in dewaterability. The best dewaterability results were found at the lowest pH value (pH = 7.0), while stirring the sludge instead of using the bubble aerator. At these settings, an orthophosphate removal of around 80% was achieved.

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Air quality is a growing concern worldwide because of its impacts on both the environment and the human health. The road transport sector is a major contributor to this poor air quality. To reduce the emission of particulate matter, all diesel passenger cars were equipped with diesel particulate filters since the EURO5b emission standard. Unfortunately, these filters can be damaged or intentionally removed during the lifetime of a vehicle. This work presents the particle number emission factors for EURO5 and EURO6 diesel passenger cars, based on the measurements of 757 vehicles. These measurements were performed at low idle, which shows a high correlation to particle number emission factors obtained during homologation cycles or real-driving emission measurements. The results show that the average Particle Number (PN) emission factors are highly impacted by high emitters present in the fleet and that the mileage has a significant impact on the PN emission factors. Finally, the estimated PN emission factors based on low idle measurements were higher by a factor 5.6 for EURO5a, 2.5 for EURO5b and 5.5 for EURO6, compared to their respective HBEFA (Handbook Emission Factors for Road Transport) emission factors. many places over the world. In Europe, air quality limit val-2 ues have been defined for PM 2.5 and PM 10 (particulate mat-3 ter with a diameter smaller than 2.5 and 10 µm, respectively): 4 the PM 2.5 yearly average must not exceed 25 µg∕m 3 while 5 PM 10 values must respect a yearly average of 40 µg∕m 3 and 6 a 24-hour average of 50 µg∕m 3 (this 24-hour average can be 7 exceeded 35 times per year). In 2016, the yearly PM 2.5 limit 8 was not respected at 5% of the European reporting stations 9 while the PM 10 daily limit was exceeded at 19% of these 10 stations. Also in 2016, long-term exposure to PM 2.5 caused 11 422 000 premature deaths in Europe [9]. 12 Additionnally to these EU limits, the World Health Or-13 ganization (WHO) defined Air Quality Guidelines (AQG) 14 which are more strict than the current EU limits. These 15 guidelines recommend that PM 2.5 remains below 10 µg∕m 3 16 for the annual average and below 25 µg∕m 3 for the 24-hour 196 on a large set of vehicles. The linear regression was obtained 197 by considering only the measurements that have PN values 198 at low idle above 10 000 #/cm 3 because of the low accuracy 199 of the diffusion charging measurement devices for very low 200 concentrations (see Figure 3). This linear regression is thus

Particulate matter (PM) is an important player of indoor air quality and a topic of great interest in terms of public health. Deciphering the complex chemical composition of indoor PM is critical to understand the association between particles components and a wide range of adverse health effects. Over the last decades, advanced analytical instrumentation has been produced capable of providing various levels of information on the chemical features of indoor PM. This article reviews the most promising of these sophisticated analytical techniques that could be employed in the identification of organic and inorganic constituents of indoor PM, including (highresolution) mass spectrometry, organic, carbonaceous and ions analytical techniques, elemental analysis techniques such as atomic spectrometry and X-ray based methods, and surface analysis techniques. A distinction is made between online and offline instrumentation, focusing on their capabilities and how they are currently being used in the targeted and untargeted analysis of PM components. This review aims to provide the indoor air chemistry community with insights into the power of the different techniques available today, so that they can be used advantageously in future studies.