Hydrothermal carbonization (HTC) is a suitable technology for managing wastes with a high moisture content, providing a carbon-rich and high energy density material called hydrochar and a process water (PW) with significant organic matter content. The aim of this work was to develop a new approach to sewage sludge management involving anaerobic digestion (AD) of the PW of dewatered waste activated sludge (DWAS) with primary sewage sludge (PSS). The process was optimized by performing semi-continuous experiments with different feed mixture compositions (10% PW/90% PSS and 5% PW/95% PSS, on a COD basis), organic loading rates (OLR; 1.5 and 2.5 g COD L -1 d -1 ), and temperature regimes (mesophilic and thermophilic). The combination of mesophilic conditions, a 10% PW/ 90% PSS feed mixture and OLR of 1.5 g COD L -1 d -1 provided concentrations of volatile fatty acids < 400 mg COD L -1 in addition to a methane yield (172 ± 11 mL CH4 g -1 CODadded), 1.15 times the value for the control test (100% PSS). Therefore, the energy content of hydrochar from HTC of DWAS followed by AD of the process water with primary sewage sludge enhances the valorization of this renewable residue.
In this paper, we analyze the performance of a positioning system based on the fusion of Ultra-Wideband (UWB) ranging estimates together with odometry and inertial data from the vehicle. For carrying out this data fusion, an Extended Kalman Filter (EKF) has been used. Furthermore, a post-processing algorithm has been designed to remove the Non Line-Of-Sight (NLOS) UWB ranging estimates to further improve the accuracy of the proposed solution. This solution has been tested using both a simulated environment and a real environment. This research work is in the scope of the PRoPART European Project. The different real tests have been performed on the AstaZero proving ground using a Radio Control car (RC car) developed by RISE (Research Institutes of Sweden) as testing platform. Thus, a real time positioning solution has been achieved complying with the accuracy requirements for the PRoPART use case.
BACKGROUND: Anaerobic treatments based on purple phototrophic bacteria (PPB) can be a more efficient and less energetically demanding alternative to aerobic biological processes currently used in refinery and petrochemistry wastewater (RPWW) treatment plants. Toxic compounds in the RPWW might compromise PPB metabolism, limiting its feasibility. In this work, seven toxic compounds that are typical components of RPWW [benzene, toluene, ethylbenzene, o-xylene (BTEX), furfural, methyl-di-ethanolamine (MDEA) and butanone] were evaluated as potential inhibitors of the specific activity and growth of PPB. RESULTS: Inhibitory K i parameters of 50% reduction of specific activity or biomass yield were calculated. Most of the BTEX compounds showed initial inhibitory effects on the specific activity, with K i values of 305 ± 9, 151 ± 17 and 84 ± 2 mg L −1 for benzene, toluene and ethylbenzene, respectively. These compounds also caused inhibition of PPB growth (K i of 411 ± 7 and 241 ± 3 mg L −1 , 26% below the control, respectively). By contrast, o-xylene affected neither the activity nor the growth. Furfural inhibited the initial specific activity (K i of 448 ± 24 mg L −1 ), with no effect over the PPB growth. However, MDEA and butanone improved the initial specific activity of PPB (15% and 40% above the control, respectively). However, butanone negatively impacted the growth which decreased to ≤40% below the control. CONCLUSIONS: Calculated inhibition thresholds for the seven toxic compounds were far above the actual concentrations found in the RPWW. Thus, anaerobic treatments based on PPB for the treatment of RPWW would not be limited by the presence of the toxic compounds studied here.
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