Adsorption presents an interesting alternative to traditional phosphorus removal technologies because it excels at achieving low levels of phosphorus (P). One leading adsorption technology is called HAIX (Hybrid Anion Exchanger) and is made from ferric oxide nanoparticles impregnated in a strong base anion exchange resin. This adsorption media, marketed as FerrIX A33E, offers great performance in terms of P removal, but requires substantial quantities of sodium hydroxide (NaOH) and sodium chloride (NaCl) to regenerate. A new version of HAIX (named WBA-2) was previously synthesized using a weak base anionic resin. It showed better regeneration abilities under lower concentrations of NaOH and no NaCl. In this study, breakthrough curves of WBA-2 and FerrIX were compared over three adsorption/regeneration cycles with 0.1 M NaOH as the regenerant solution. FerrIX was able to treat 1630 bed volumes in the first cycle, but only managed to treat 800 bed volumes in the third cycle. WBA-2 was able to keep its full treatment capacity with 1470 bed volumes treated in the first cycle and 1500 for the third. To push the regeneration efficiency of WBA-2 even further, its regeneration was evaluated at 24 degrees C, 50 degrees C and 80 degrees C. Higher temperature during regeneration yielded higher performance with 79 %, 85 % and 91 % +/- 1 % of regeneration efficiency for the three temperatures in increasing order. Finally, this study discusses the possibility of using onsite electrolysis to provide the consumables needed for the regeneration of HAIX, and demonstrates how using higher temperatures during electrolysis and regeneration of HAIX can improve overall operational performance.

This study presents an innovative technical integration for concomitant nutrient recovery from source-separated urine. While cation exchange is known for efficient K+ recovery, it faces competition due to the high molarity of NH4+ in hydrolyzed urine. This study proposes inhibiting urease activity to facilitate the recovery of K+ and urea from fresh urine. Na-chabazite was first proposed as a urease inhibitor in this study, reducing urease activity by 50 %. Wood biochar, with its high porosity (308.0 m2/g) and polar functional groups, shows a urea adsorption capacity of 25.4 mg/g, which can be further improved by steam activation. The isotherm analysis suggests that urea adsorption onto biochar follows a multi-layer adsorption process. Finally, an integrated process is suggested: "Na-chabazite and Biochar adsorption -* urea hydrolysis -* struvite precipitation + ammonia stripping-acid scrubbing", ensuring efficient recovery of urea, NH4+, PO43-, and K+ from source-separated urine.

This study investigated the recovery of K+ along with NH4+-N and PO43--P from hydrolyzed urine by technical integra-tion. The K adsorption capacities of biochar, clinoptilolite, artificial zeolite and chabazite were firstly compared. Due to the high K recovery efficiency and additional P recovery capacity, Na-chabazite was selected as the adsorbent in this study. Its kinetics and isotherm analysis indicated that the high molarity of NH4+-N seriously hindered the K adsorption onto Na-chabazite in synthetic hydrolyzed urine (SHU). However, this competition between NH4+ and K+ got dimin-ished when their molarity is the same, i.e. in the SHU after ammonia stripping (ASSHU). Based on this key finding, Na-chabazite adsorption was integrated with ammonia stripping and struvite precipitation under different configurations. Simultaneous ammonia stripping was inadequate to diminish the competitive effect of NH4+ on K+ adsorption. De-pending on the demand for fertilizer, two sequential configurations were recommended, respectively.

In order to avoid eutrophication of freshwater systems, regulations all around the world have become increasingly stringent toward the maximum phosphate concentration allowed in wastewater discharges. Traditional phosphate removal methods such as chemical precipitation and enhanced biological phosphorus removal struggle to lower phosphate levels to the new requirements. Hybrid anion exchange nanotechnology (HAIX-Nano) is composed of a selective adsorption material able to remove phosphate down to levels close to zero. Moreover, HAIX-Nano is not affected by intermittent flow and does not produce sludge making it an interesting alternative. The regeneration process of HAIX-Nano typically requires a chemical solution with a high concentration of sodium hydroxide (NaOH) and sodium chloride (NaCl) (2–5% w/w of each). To lower the environmental impact and the operational cost of the technology, this study aims to enhance the HAIX-Nano regeneration efficiency. Therefore, the backbone of HAIX-Nano, which is normally a strong base anionic (SBA) resin, was changed for a weak base anionic (WBA) resin. The resulting material (WBA-2) exhibited a higher adsorption capacity than the traditional version of HAIX-Nano (SBA-1) under the tested conditions, while also showing a much higher regeneration efficiency. For a desorption solution of only 0.4% NaOH and no NaCl, WBA-2 showed an average regeneration efficiency of 78 ± 1% compared to SBA-1 with 24 ± 1%.

Limonene dioxide is a key intermediate molecule for the development of biobased polycarbonates or nonisocyanate polyurethanes. In this work the epoxidation of limonene to limonene dioxide using in-situ-generated dimethyl dioxirane as the oxidizing agent under both conventional agitation and ultrasound has been compared. The time required to completely convert limonene to limonene dioxide with 100% yield using ultrasound was only 4.5 min at room temperature. In comparison, when conventional agitation using a magnetic stirrer is used, the required time to reach a 97% yield of limonene dioxide was 1.5 h. The epoxidation of alpha-pinene has also been studied using both agitation techniques. Epoxidation of alpha-pinene to alpha-pinene oxide under ultrasound required only 4 min with an obtained yield of 100%, while in comparison with the conventional method the reaction time was 60 min. As for other terpenes, beta-pinene was converted to beta-pinene oxide in only 4 min whereas farnesol yielded 100% of the triepoxide in 8 min. Carveol, a limonene derivative, was converted to carveol dioxide with a yield of 98%. In the epoxidation reaction of carvone using dimethyl dioxirane the conversion was 100% in 5 min, but only 7,8-carvone oxide was produced.

Limonene dioxide is a platform molecule for the production of new biopolymers. First attempts at limonene epoxidation were made by using low-coordination titanium supported on SBA-16 as the catalyst using tert-butyl hydroperoxide as the oxidizing agent, but no limonene dioxide was obtained. When limonene was substituted by 1,2-limonene oxide, the yield of limonene dioxide was only 13% in the same conditions. Two other techniques, both using in situ generated dimethyl dioxirane by the reaction of acetone with Oxone, have been studied and compared. These reactions are carried out in semibatch conditions and at room temperature. The first double epoxidation of limonene was performed in a conventional biphasic organic-water system and the other in excess acetone. The former epoxidation of limonene using ethyl acetate as the organic phase allowed reaching 95% conversion and yielding 33% of limonene dioxide. In comparison, when the reaction was performed in acetone, a limonene dioxide yield of 97% was observed under optimized conditions. The double epoxidation of limonene should be carried out at room temperature with a flowrate of 4 mL min(-1) of aqueous Oxone for a period of 45 min with a stoichiometric excess of 30% of Oxone.