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Abstract Hydrothermal treatment (HT) is a promising technology to enhance anaerobic digestion (AD) of municipal sludge. However, the capacity of pre‐ and inter‐stage HT (i.e., HT‐AD and AD‐HT‐AD, respectively) to enhance the digestibility of municipal sludge has not been sufficiently explored. This study compared the efficacy of pre‐ and inter‐stage HT performed from 90 to 185°C to enhance methane production from a mixture of primary sludge and waste activated sludge using mesophilic (35°C) biochemical methane potential tests. In both configurations, sludge solubilization increased with HT temperature. HT‐AD, and to a greater extent AD‐HT‐AD, increased the release of ammonium nitrogen. Even though HT at 185°C dramatically increased sludge solubilization, the overall specific methane yield with HT at 185°C was lower than or comparable to that at lower HT temperatures in the HT‐AD and AD‐HT‐AD configurations, respectively. Up to 155°C HT, the overall specific methane yield with the HT‐AD configuration was higher by 4.9%–8.3% compared to the AD‐HT‐AD configuration. However, when the HT energy was considered, compared to the control (i.e., AD of sludge without HT), the net energy gain (ΔE) decreased as the HT temperature increased, becoming negative at an HT of 185°C. The AD‐HT‐AD configuration resulted in a higher overall volatile solids destruction (by 8.1 to 20.1%). In conclusion, for municipal sludge with a relatively high ultimate digestibility, as was the case in this study, HT‐AD is preferable as it has a smaller footprint and is easier to operate than the AD‐HT‐AD configuration. However, given the significantly higher volatile solids destruction in the AD‐HT‐AD configuration, compared to the HT‐AD configuration, AD‐HT‐AD may be more beneficial considering post‐AD sludge handling processes. Practitioner pointsHydrothermal treatment (HT) increased the rate and extent of methane production from municipal sludge mixture.155°C was the optimal temperature for either pre‐ or inter‐stage HT to increase biogas production.Pre‐ and inter‐stage HT resulted in comparable ultimate methane production.Pre‐stage HT is preferable to inter‐stage HT (smaller footprint, easier to operate).AD‐HT‐AD resulted in significantly higher volatile solids destruction compared to the HT‐AD configuration. 

Abstract Separating molecules or ions with sub-Angstrom scale precision is important but technically challenging. Achieving such a precise separation using membranes requires Angstrom scale pores with a high level of pore size uniformity. Herein, we demonstrate that precise solute-solute separation can be achieved using polyamide membranes formed via surfactant-assembly regulated interfacial polymerization (SARIP). The dynamic, self-assembled network of surfactants facilitates faster and more homogeneous diffusion of amine monomers across the water/hexane interface during interfacial polymerization, thereby forming a polyamide active layer with more uniform sub-nanometre pores compared to those formed via conventional interfacial polymerization. The polyamide membrane formed by SARIP exhibits highly size-dependent sieving of solutes, yielding a step-wise transition from low rejection to near-perfect rejection over a solute size range smaller than half Angstrom. SARIP represents an approach for the scalable fabrication of ultra-selective membranes with uniform nanopores for precise separation of ions and small solutes. 

AbstractThe recovery and reuse of phosphorus (P) from wastewater treatment process is a critical and viable target for sustainable P utilization. This study explores a novel approach of integrating ultrafine mineral particles into hydrogel matrixes for enhancing the capacity of phosphate adsorption. Dolomite‐alginate (DA) hydrogel beads were prepared by integrating ball‐milled, ultrafine dolomite powders into calcium cross‐linked alginate hydrogel matrix. The adsorption isotherms followed a Langmuir–Freundlich adsorption model with higher specific adsorption capacity than those reported in literature. The kinetics of phosphate adsorption suggest that the adsorption is diffusion controlled. Investigation of adsorption capacity at differentpHshowed a maximum adsorption capacity in thepHrange of 7–10. Lastly, we demonstrated that theDAbeads are capable of slowly releasing most of the adsorbed phosphate, which is an important criterion for them to be an effective phosphorous fertilizer. This study, usingDAcomposite hydrogel as an example, demonstrates a promising strategy of immobilizing ultrafine mineral adsorbents into biocompatible hydrogel matrix for effective recovery of phosphorous resource from wastewater. Practitioner pointsIntegration of dolomite and alginate hydrogel beads is demonstrated using ball milling.Ball milling process increases the specific adsorption capacity of dolomite on phosphorus.Adsorption isotherms, kinetics, andpHeffects of the dolomite–alginate beads are investigated.The dolomite–alginate beads can be used as slow‐release phosphorus fertilizer.