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Economic and environmental aspects render nitrogen removal from oil loads increasingly more necessary. Studies have proven that it is possible to achieve high selectivity to quinoline hydrodenitrogenation products using PtMo bimetallic catalysts supported on zeolites. However, the reaction follows the route of higher hydrogen consumption. The main products in this reaction are propylcyclohexene, propylbenzene, and propylcyclohexane, being more selective for propylcyclohexane, which is directly related to increased hydrogen consumption. Therefore, the identification of the best conditions of temperature and hydrogen flow to make the process more selective for propylbenzene is of interest. The study conducted in UniSim® Software showed considerable improvements in selectivity with increasing the temperature of reaction between 450 and 500 °C. Additionally, the catalytic tests confirmed that the bimetallic catalyst reached higher selectivity when the temperature of 460 °C was used, as determined by simulation. The experimental results and the simulation analysis showed that molybdenum in catalysts is essential for HDN reactions and that temperature is a key factor toward propylbenzene selectivity. [ABSTRACT FROM AUTHOR]

Livestock wastewater contains a large amount of nutrients that are available for recovery. In this study, a proof of concept process based on forward osmosis (FO) was proposed and investigated for in situ formation of struvite from digested swine wastewater. This FO system took advantage of a drawback – reverse solute flux (RSF) and used the reverse-fluxed Mg 2+ for struvite precipitation, thereby accomplishing recovery of both water and nutrient. With 0.5 M MgCl 2 as a draw solution, high-purity struvite formed spontaneously in the feed solution and the water flux through the FO membrane reached 3.12 LMH. The precipitated struvite was characterized and exhibited a similar composition to that of commercial struvite. The FO system achieve >50% water recovery and >93% ammonium nitrogen removal from the digested swine wastewater; in particular, it obtained >99% phosphate recovery, much higher than 60.7% removal via direct MgCl 2 addition (without FO treatment). The recovered products (both struvite and water) could potentially generate a value of 1.35 $ m −3 . The results of this study have demonstrated the feasibility of nutrient recovery from livestock wastewater promoted by FO treatment. [ABSTRACT FROM AUTHOR]

This study investigated the effect of N-acyl-L-homoserine lactones (AHLs) and EPS on anammox activity, and identified the relationship between AHLs and EPS. The effects of AHLs and different EPS fractions (loosely bound (LB) and tightly bound (TB) EPS) from denitrification sludge (DS) and perchlorate reducing sludge (PRS) on anammox activity were conducted by batch experiments. Compared with the control experiment, the nitrogen removal rate was increased by 82.0%, 73.9% and 73.0%, respectively, when adding DS-EPS (integral DS EPS), PRS-EPS (integral PRS EPS) and DS-LB in anammox biomass. EPS fractions of DS and PRS contained the same kinds of AHLs, including C4-HSL, C6-HSL and C8-HSL, as identified by HPLC-MS. C4-HSL and C6-HSL at 0.1 mg L −1 concentration effectively improved the nitrogen removal rate by induceing the expression of anammox active genes during the anammox process. This study provides a new idea for efficient nitrogen removal from anammox bacteria. [ABSTRACT FROM AUTHOR]

Treatment wetlands have been proved to be more effective than conventional treatment processes in case of high-strength wastewater containing high concentrations of ammonium nitrogen and recalcitrant organic matter. In this study nitrogen removal processes and reliability of nitrogen removal at two identical pilot-scale multistage treatment wetlands (MTWs) receiving real, non-synthetic wastewater were discussed. The wastewater discharged to pilot-scale subsurface flow MTWs contained high ammonium nitrogen concentrations and limited biodegradable organic matter (OM) concentrations. One of the pilot MTWs was fed with landfill leachate (LL) and another one with reject water from sewage sludge centrifugation (RW). In the first season of operation both MTWs reached very high (95–99%) efficiency of total nitrogen (TN) removal, which was explained by adsorption to the substrate. In the later period, TN was removed in a sequence of nitrification and denitrication processes with lower efficiency (40–86%). The denitrification process was the limiting one at the LL treating site because of too low carbon supply. Still, during the whole investigation period TN outflow concentrations were at the level that allows for co-treatment of the effluent in municipal wastewater treatment plants without risk for biological treatment processes. In 90% of samples TN concentration was below 200 mg/l and in 60% of samples it was below 145 mg/l. [ABSTRACT FROM AUTHOR]

Cu-SSZ-13/cordierite monolithic catalyst was prepared by in situ hydrothermal synthesis method. The physicochemical properties of the as-prepared Cu-SSZ-13/cordierite were investigated by X-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, N 2 -adsorption, inductively coupled plasma, X-ray photoelectron spectroscopy, and solid-state NMR techniques. The removal of nitrogen oxides (NO x ) from simulated diesel vehicle exhaust gas was performed using fixed-bed reactor. The effects of crystallization time and addition of HF during hydrothermal synthesis, reaction space velocity, and aging treatment of catalyst on the catalytic performances of NO x reduction reactions were investigated. The results indicate that the optimum crystallization time was 72 h. Highly crystalline structure of zeolite Cu-SSZ-13 was formed, in a close combination with a carrier, via one step hydrothermal process. Cu-SSZ-13/cordierite showed excellent DeNO x performance for selective catalytic reduction (SCR) and anti-aging properties in a simulated diesel exhaust gas under a high space velocity. At a high space velocity of 72,000 h −1 , the highest conversion and N 2 selectivity of 94% and 90%, respectively, were achieved. After the aging for 50 h at 720 °C, NO x reduction rate was still >80% in the temperature range of 350–550 °C. The larger height to diameter ratio of the same catalysts enhanced the NH 3 -SCR catalytic activity and broadened the active temperature window. The addition of HF increased the catalytic activity and anti-aging performance of the sample. [ABSTRACT FROM AUTHOR]