The results show that the rich heterotrophic carbon source in the sludge extract can be used as an excellent medium for Chlorella. It provides new ideas for the harmless utilization of surplus sludge as a resource. At the same time, the use of nutrients in the sludge extract to cultivate Chlorella is of great significance to low-cost algae cultivation.In the previous study, greenhouse gas CO2 was successfully used as the precipitator to realize its carbonation by calcium ions in seawater with the help of magnesium oxide. In this study, the reaction process was firstly analyzed by a proposed reaction mechanism, and then the dynamic simulation of the gas-liquid-solid system was carried out via kinetic Monte Carlo simulation. Based on the reaction mechanism, the continuous experimental study was realized in a bubble column. The effects of air flow rate, carbon dioxide flow rate and temperature on the effectiveness evaluation indexes of decalcification efficiency, total mass transfer coefficient and carbon sequestration rate were studied. Finally, a bonnet tower with a diameter of 1 m and a height of 8 m was built to carry out the pilot test. In the laboratory experiments, the calcium removal rate reached 94%, the carbon sequestration rate reached 63.6%, and pure micron calcium carbonate products were obtained. The decalcification rate reached 95% in the pilot test, which is consistent with the results of the laboratory experiment.Natural apatites have previously shown a great capacity for phosphate retention from wastewater. However, its fine particle size distribution may lead to a premature clogging of the filter. Accordingly, a granulated apatite product was developed and manufactured in order to control the particle size distribution of the media. Experiments were conducted on laboratory columns to assess their phosphorus retention capacity, to identify the processes involved in phosphorus retention and to evaluate their kinetic rates. The results showed phosphorus retention capacities of 10.5 and 12.4 g PO4-P·kg-1 and kinetic rate coefficients in the range of 0.63 and 0.23 h-1 involving lower values than those found for natural apatites in previous studies. Scanning Electron Microscopy images showed that apatite particles in the granules were embedded in the binder and were not readily accessible to act as seeds for calcium phosphate precipitation. The retention processes differ depending on the supersaturation of the solution with respect to calcium phosphate phases at low calcium concentrations (69.8 ± 3.9 mg·L-1), hydroxyapatite precipitates fill up the porosity of the binder up to a depth of 100-300 μm from the granule surface; at higher calcium concentrations (112.7 ± 7.4 mg·L-1) precipitation occurs at the granule surface, forming successive layers of hydroxyapatite and carbonated calcium phosphates.The fate of pathogen indicators (Escherichia coli – EC, intestinal enterococci – IE, RNA-F bacteriophages and spores of sulfite reducing bacteria – SSR) was extensively studied in Parisian large-scale wastewater treatment plants (WWTPs), based on conventional activated sludge, biofiltration or membrane bioreactor (MBR) processes. Between 14 and 87 campaigns were performed between 2014 and 2018 in five WWTPs. High removals of 3 log for both EC and IE, and lower removals of 1-2 log for SSR and RNA-F bacteriophages, were observed in conventional activated sludge and biofiltration WWTPs. The MBR WWTP achieves notably greater removals of 4.5-5.5 log for faecal bacteria and 3-4 log for SSR and RNA-F bacteriophages. This WWTP is the only one already in compliance with reuse standards, the other ones being non-compliant because of SSR and RNA-F bacteriophages. The implementation of a micro-grain activated carbon process would increase the WWTP removals of 0.8 log for faecal bacteria, due to particles retention, with ufficient. Correlations were also found between the removals of pathogen indicators and the removals of physico-chemical parameters, but they are not good enough to allow performance predictions.Rapid filling in horizontal partially filled pipes with entrapped air may result in extreme pressure transients. This study advanced the current understanding of dynamic behavior of entrapped air above tailwater (the initial water column with a free surface in a partially filled pipe) through rigid-column modeling and sensitivity analysis of system parameters. Water and air were considered as incompressible fluid and ideal gas, respectively, and the continuity and momentum equations for water and a thermodynamic equation for air were solved by using the fourth order Runge-Kutta method. find more The effects of system parameters were examined in detail, including tailwater depth, entrapped air volume, driving head, pipe friction, and relative length of entrapped air and pipe. The results indicate that the presence of tailwater can mitigate the peak pressure when with identical initial volumes of entrapped air, as it can be considered to reflect a certain amount of loss of the net driving head. However, the peak pressure can increase as much as about 45% for the cases with fixed pipe length, due to the reduction in the initial entrapped air volume. The rise time for the first peak pressure was closely related to pipe friction, whereas the oscillation period (defined as the time duration between the first and second peaks) was virtually irrelevant. The applicability of the rigid-column model was discussed, and a time scale relevant indicator was proposed. When the indicator is larger than 20, the relative difference between the peak pressure estimation and experimental measurements is generally below 5%.For improving the management of watershed eutrophication, methods for measuring bioavailable phosphorus (BAP) are more important than measurements of total phosphorus (TP). BAP in particulate form (P-BAP) is an important substance that promotes eutrophication, especially during rainy seasons. Only a portion of particulate phosphorus (PP) is taken up by algae that contribute to eutrophication. Erosion and runoff associated with rainfall transport PP bound to sediments and soil particles to surface waters, thus increasing PP concentration. This research evaluated an extraction method using an ultrasonic washing machine for extraction time and frequency. Extraction at a frequency of 28-45 kHz and an extraction time of 1 min resulted in extracted P concentrations almost the same as concentrations extracted using conventional methods. This new method requires less time and is more efficient than conventional methods because it extracts P from multiple samples in a single step. Results indicate that extraction using an ultrasonic washing machine is a promising method for rapidly obtaining BAP from sediments and soil particles.