Anaerobic digestion of animal by-products : effect of substrate concentration

In this work, the anaerobic valorization of Category 2 Animal By-Products (ABP) to biogas is assessed. Category 2 ABP other than manure, digestive tract content and milk, usually called ‘bone flour’ and hereafter designated as Category 2 ABP* have been considered as a sustainable substrate for anaerobic digestion, due to their protein and grease content. Main characteristics of Category 2 ABP* are as follows: total solids (TS) = 916 ± 1 mg g-1 residue, volatile solids (VS) = 904 ± 5 mg g-1TS, total Kjeldahl nitrogen (TNK) = 84 ± 9 mg g-1TS, total phosphorus (TP) = 6.2 ± 0.9 mg g-1TS, chemical oxygen demand (COD) = 1221 ± 173 mg O2 g-1TS and oil/grease = 278 ± 2 mg g-1TS. The ratio COD/N/P is 164 /8 /1. In this work, anaerobic biodegradability tests were performed by ‘multiple flask’ reactor method. Initial conditions of the experiment are: all flasks have the same content and it is assumed that the progress of hydrolysis, acidogenesis and methanogenesis is similar in all flasks. Sampling was based on the quantitative analysis of content of the flask withdrawn from the reactor system. [1]. Three concentrations of substrate were tested: 2, 5 and 10 % TS (dry weight of substrate per volume). To evaluate the performance of the reactors loaded with the three concentrations of substrate, methane and soluble COD were measured. The concentration of 2 % TS resulted in higher production of accumulated methane compared with the other concentrations. At 25th day of incubation soluble COD reached the same value for the three concentrations, approximately 450 - 500 mg g-1VS_COD. After that period, the soluble COD concentration started to decrease for 2 % TS while it continued to increase for 5 and 10 % TS. These results suggest occurrence of methanogenic inhibition for the higher initial concentrations of substrate. The pH varied between 7.00 – 7.95 for 2 % TS, 6.76 – 7.70 for 5 % TS and 6.69 - 7.18 for 10 % TS. Inhibitory Volatile Fatty Acids (VFA) were not at the limiting concentrations for methanogenesis [2], however ammonia concentrations higher than 3700 mg NH4 + L-1 were observed for both, 5 and 10 % TS, and thus its inhibitory effects were observed [3]

Fractional-order position and force robot control

This paper presents the implementation of fractional-order algorithms both for hybrid and cascade position/force control of robotic manipulators. The systems performance and robustness is analyzed in the time domain. The impact effects of the robot gripper with the environment are also investigated.N/

Anaerobic biodegradability of category 2 animal by-products : methane potential and inoculum source

Category 2 animal by-products that need to be sterilized with steam pressure according Regulation (EC) 1774/2002 are studied. In this work, 2 sets of experiments were performed in mesophilic conditions: (i) biomethane potential determination testing 0.5%, 2.0% and 5.0% total solids (TS), using sludge from the anaerobic digester of a wastewater treatment plant as inoculum; (ii) biodegradability tests at a constant TS concentration of 2.0% and different inoculum sources (digested sludge from a wastewater treatment plant; granular sludge from an upflow anaerobic sludge blanket reactor; leachate from a municipal solid waste landfill; and sludge from the slaughterhouse wastewater treatment anaerobic lagoon) to select the more adapted inoculum to the substrate in study. The higher specific methane production was of 317 mL CH4 g−1 VSsubstrate for 2.0% TS. The digested sludge from the wastewater treatment plant led to the lowest lag-phase period and higher methane potential rate.This work was partially supported by project PEst-C/EQB/LA0020/2011, financed by FEDER through COMPETE - Programa Operacional Factores de Competitividade and by FCT - Fundacao para a Ciencia e a Tecnologia. FCT is acknowledged for the financial support given to Tatiana Pozdniakova through the PhD scholarship (SFRH/BD/45144/2008) and Jose Carlos Costa through the grant (SFRH/BDP/48962/2008)

Statistical modelling of dual-arm robotic systems

The article presents a new approach to the analysis and design of two-arm robotic systems. Usually, system descriptions are based on a set of differential equations which require laborious computations. This motivates the need of alternative models based on other mathematical concepts. The proposed statistical method gives clear guidelines towards the robotic systems analysis and development.N/

Fractional control of two arms working in cooperation

This paper analyzes the performance of two cooperative robot manipulators. It is studied the implementation of fractional-order algorithms in the position/force control of two robots holding an object. The experiments reveal that fractional algorithms lead to performances superior to classical integer-order controllers.N/

Development of a Multicommutated Flow System with Chemiluminometric Detection for Quantification of Gentamicin in Pharmaceuticals

A new flow procedure based on multicommutation with chemiluminometric detection was developed to quantify gentamicin sulphate in pharmaceutical formulations. This approach is based on gentamicin's ability to inhibit the chemiluminometric reaction between luminol and hypochlorite in alkaline medium, causing a decrease in the analytical signal. The inhibition of the analytical signal is proportional to the concentration of gentamicin sulphate, within a linear range of 1 to 4 μg mL−1 with a coefficient variation <3%. A sample throughput of 55 samples h−1 was obtained. The developed method is sensitive, simple, with low reagent consumption, reproducible, and inexpensive, and when applied to the analysis of pharmaceutical formulations (eye drops and injections) it gave results with RSD between 1.10 and 4.40%

Fractional-order position/force robot control

In this paper it is studied the implementation of fractional-order algorithms in position/force control of two cooperating robotic manipulaotrs. The performance and system robustness are analyzed in the time and frequency domains. The effect of backlash and flexibility at the robot joints is also investigated.N/