Amorim Norma C S, Amorim Eduardo L C, Kato Mario T, Florencio Lourdinha, Gavazza Savia
Laboratório de Saneamento Ambiental, Departamento de Engenharia Civil e Ambiental, Universidade Federal de Pernambuco, Av. Acadêmico Hélio Ramos, s/n. Cidade Universitária, Recife, PE, CEP: 50740-530, Brazil.
Instituto Federal de Alagoas, Campus de Satuba, Rua 17 de Agosto, s/n. Centro, Satuba, AL, CEP: 57120-000, Brazil.
Biodegradation. 2018 Feb;29(1):41-58. doi: 10.1007/s10532-017-9812-y. Epub 2017 Nov 11.
Manipueira is a carbohydrate-rich agro-industrial waste from cassava processing. It is considered well suitable for biotechnological processes, such as hydrogen and carboxylic acids production, due to the high content of easily degradable organic matter. However, the proper methanogenesis inhibition method, inoculum type, and organic loads are factors still limiting the processes. The objective in this work was to evaluate the effects of such factors on byproducts production in anaerobic reactors. Batch experiments were conducted with 2.3-L flasks during two operational phases. In the first phase (P1), inhibition of methanogens in the sludge was evaluated using acetylene (1% v/v of headspace) and heat treatment (120 °C, 1 atm for 30 min). In the second phase (P2), three inoculum types obtained from common anaerobic sludges (bovine rumen and sludges from municipal and textile industrial wastewater treatment plants) were individually assayed. P2 aimed to identify the best inoculum, based on hydrogen production ability, which was tested for three initial concentrations of manipueira in terms of chemical oxygen demand (COD) (10, 20 and 40 g O/L). Results of P1 indicated that either acetylene or heat treatment efficiently inhibited methanogenesis, with no methane production. However, the maximum H production potential by applying heat treatment (~ 563 mL) was more than twice compared with that by acetylene treatment (~ 257 mL); and butyrate was the main carboxylic acid by-product (~ 3 g/L). In P2 experiments after sludge heat treatment, the highest hydrogen yield (1.66 ± 0.07 mol H/mol glucose) and caproic acid production (~ 2 g/L) were observed at 20 g O/L of manipueira COD, when bovine rumen was the inoculum. The primary metabolic degradation products in all P2 experiments were ethanol, acetic, butyric, propionic and caproic acids. The finding of caproic acid detection indicated that the applied conditions in manipueira anaerobic degradation favored carbon chain elongation over methanogenesis.
木薯渣是木薯加工过程中富含碳水化合物的农业工业废弃物。由于其易降解有机物含量高，被认为非常适合用于生物技术过程，如生产氢气和羧酸。然而，合适的甲烷生成抑制方法、接种物类型和有机负荷仍是限制这些过程的因素。本研究的目的是评估这些因素对厌氧反应器中副产物产生的影响。在两个运行阶段使用2.3升烧瓶进行了批次实验。在第一阶段（P1），使用乙炔（顶空体积的1% v/v）和热处理（120°C，1个大气压，30分钟）评估污泥中甲烷菌的抑制情况。在第二阶段（P2），分别对从常见厌氧污泥（牛瘤胃以及城市和纺织工业废水处理厂的污泥）中获得的三种接种物类型进行了分析。P2旨在根据产氢能力确定最佳接种物，并针对木薯渣的三种初始化学需氧量（COD）浓度（10、20和40 g O/L）进行了测试。P1的结果表明，乙炔或热处理均能有效抑制甲烷生成，无甲烷产生。然而，热处理的最大产氢潜力（约563毫升）是乙炔处理（约257毫升）的两倍多；丁酸盐是主要的羧酸副产物（约3克/升）。在P2实验中，污泥热处理后，当以牛瘤胃为接种物，木薯渣COD为20 g O/L时，观察到最高的氢气产率（1.66±0.07摩尔氢气/摩尔葡萄糖）和己酸产量（约2克/升）。所有P2实验中的主要代谢降解产物为乙醇、乙酸、丁酸、丙酸和己酸。己酸检测结果表明，木薯渣厌氧降解所采用的条件有利于碳链延长而非甲烷生成。
