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This study evaluated a novel three-stage process devoted to the cascade production of lactate, biohydrogen and methane from tequila vinasse (TV), with emphasis on attaining a high and stable biohydrogen production rate (HPR) by utilizing lactate as biohydrogen precursor. In the first stage, tailored operating conditions applied to a sequencing batch reactor were effective in sustaining a lactate concentration of 12.4 g/L, corresponding to 89% of the total organic acids produced. In the second stage, the stimulation of lactate-centered dark fermentation which entails the decoupling of biohydrogen production from carbohydrates utilization was an effective approach enabling stable biohydrogen production, having HPR fluctuations less than 10% with a maximum HPR of 12.3 L/L-d and a biohydrogen yield of 3.1 L/LTV. Finally, 1.6 L CH4/L-d and 6.5 L CH4/LTV were obtained when feeding the biohydrogen fermentation effluent to a third methanogenic stage, yielding a global energy recovery of 267.5 kJ/LTV.

La gazéification au plasma de la biomasse ligneuse, non ligneuse et algale brute et torréfiée à l'aide de trois agents de gazéification différents (air, vapeur et CO2) est effectuée par une analyse thermodynamique. Les impacts de la matière première et de l'atmosphère de réaction sur divers indices de performance tels que le rendement du gaz de synthèse, les émissions de polluants, le rapport énergie plasmatique/production de gaz de synthèse (PSR) et l'efficacité de la gazéification du plasma (PGE) sont étudiés. Les résultats montrent que la gazéification au plasma de CO2 donne le PSR le plus bas, conduisant ainsi à la PGE la plus élevée parmi les trois atmosphères réactionnelles. La biomasse torréfiée présente un rendement accru en gaz de synthèse et en PGE, mais est plus susceptible d'avoir un impact environnemental négatif des polluants N/S par rapport à la biomasse brute, en particulier pour la paille de riz. Cependant, l'exception concerne le marc de raisin torréfié et les macroalgues qui produisent des quantités plus faibles d'espèces S dans des atmosphères de vapeur et de CO2. Dans l'ensemble, le bois de pin torréfié présente les meilleures performances pour la production de gaz de synthèse de haute qualité contenant de faibles impuretés parmi les matières premières étudiées. La gasificación por plasma de biomasa leñosa cruda y torrefactada, no leñosa y de algas utilizando tres agentes gasificantes diferentes (aire, vapor y CO2) se realiza a través de un análisis termodinámico. Se estudian los impactos de la materia prima y la atmósfera de reacción en varios índices de rendimiento, como el rendimiento de gas de síntesis, las emisiones contaminantes, la relación de producción de energía de plasma a gas de síntesis (PSR) y la eficiencia de gasificación de plasma (PGE). Los resultados muestran que la gasificación con plasma de CO2 da el PSR más bajo, lo que conduce al PGE más alto entre las tres atmósferas de reacción. La biomasa torrefactada muestra un mayor rendimiento de gas de síntesis y PGE, pero es más probable que tenga un impacto ambiental negativo de los contaminantes N/S en comparación con los crudos, especialmente para la paja de arroz. Sin embargo, la excepción es para el orujo de uva torrefactado y las macroalgas que producen menores cantidades de especies S en atmósferas de vapor y CO2. En general, la madera de pino torrefactada tiene el mejor rendimiento para producir gas de síntesis de alta calidad que contiene bajas impurezas entre las materias primas investigadas. Plasma gasification of raw and torrefied woody, non-woody, and algal biomass using three different gasifying agents (air, steam, and CO2) is conducted through a thermodynamic analysis. The impacts of feedstock and reaction atmosphere on various performance indices such as syngas yield, pollutant emissions, plasma energy to syngas production ratio (PSR), and plasma gasification efficiency (PGE) are studied. Results show that CO2 plasma gasification gives the lowest PSR, thereby leading to the highest PGE among the three reaction atmospheres. Torrefied biomass displays increased syngas yield and PGE, but is more likely to have a negative environmental impact of N/S pollutants in comparison with raw one, especially for rice straw. However, the exception is for torrefied grape marc and macroalgae which produce lower amounts of S-species under steam and CO2 atmospheres. Overall, torrefied pine wood has the best performance for producing high quality syngas containing low impurities among the investigated feedstocks. يتم تغويز البلازما للكتلة الحيوية الخشبية وغير الخشبية والطحالب باستخدام ثلاثة عوامل تغويز مختلفة (الهواء والبخار وثاني أكسيد الكربون) من خلال تحليل ديناميكي حراري. يتم دراسة تأثيرات المواد الخام وجو التفاعل على مؤشرات الأداء المختلفة مثل إنتاج غاز التخليق وانبعاثات الملوثات وطاقة البلازما على نسبة إنتاج غاز التخليق (PSR) وكفاءة تغويز البلازما (PGE). تظهر النتائج أن تغويز بلازما ثاني أكسيد الكربون يعطي أقل نسبة PSR، مما يؤدي إلى أعلى نسبة PGE بين أجواء التفاعل الثلاثة. تعرض الكتلة الحيوية Torrefied زيادة إنتاج غاز التخليق و PGE، ولكن من المرجح أن يكون لها تأثير بيئي سلبي على ملوثات N/S مقارنة بالملوثات الخام، خاصة بالنسبة لقش الأرز. ومع ذلك، فإن الاستثناء هو لمارك العنب والطحالب الكبيرة التي تنتج كميات أقل من الأنواع S تحت أجواء البخار وثاني أكسيد الكربون. بشكل عام، يتمتع خشب الصنوبر المغطى بأفضل أداء لإنتاج غاز صناعي عالي الجودة يحتوي على شوائب منخفضة بين المواد الأولية التي تم التحقيق فيها.

The developments of mixed culture polyhydroxyalkanoate production has been directed to maximize the biomass PHA content with limited attention to polymer quality. Direct comparison of PHA accumulation literature is challenging, and even regularly contradicting in reported results, due to underlying differences that are not well expressed. A study was undertaken to systematically compare the commonly reported process conditions for PHA accumulation by full-scale municipal activated sludge. A biomass acclimation step combined with a pulse-wise feeding strategy resulted in maximum average PHA contents and product yields. pH control and active nitrification did not result in observable effects on the PHA productivity. Under these conditions a high molecular weight polymer (1536 ± 221 kDa) can be produced. Polymer extraction recoveries were influenced by the PHA molecular weight. A standard protocol for an activated sludge PHA accumulation test including downstream processing and standardized extraction has been developed and is available as supplementary material.

Energy-rich sludge can be obtained from primary clarifiers preceding biological reactors. Alternatively, the incoming wastewater can be sent to a very-high-loaded activated sludge system, i.e., a so-called A-stage. However, the effects of applying an A-stage instead of a primary clarifier, on the subsequent sludge digestion for long-term operation is still unknown. In this study, biogas production and permeate quality, and filterability characteristics were investigated in a lab-scale anaerobic membrane bioreactor for primary sludge and A-stage sludge (A-sludge) treatment. A higher specific methane yield was obtained from digestion of A-sludge compared to primary sludge. Similarly, specific methanogenic activity was higher when the anaerobic membrane bioreactor was fed with A-sludge compared to primary sludge. Plant-wide mass balance analysis indicated that about 35% of the organic matter in wastewater was recovered as methane by including an A-stage, compared to about 20% with a primary clarifier.