With the gradual increase in algal waste, its disposal has become a key problem in the field of marine environmental protection. Anaerobic digestion (AD) of algal biomass is one potential method for its treatment in a beneficial manner. However, AD of algae is hindered because of strong resilient cell walls, and hence, pretreatment of algae biomass before AD is an essential process. In this study, green algae (Enteromorpha) were used as the research substrate to explore the damage and impact of NaOH–urea pretreatment on biomass. Scanning electron microscopy and thermogravimetric analysis were used to analyze the damage of the cell wall structure of Enteromorpha via NaOH–urea pretreatment. The response surface method (RSM) was used for the optimization of pretreatment conditions to obtain the best experimental conditions. The experimental independent variables were pretreatment time, pretreatment temperature, and NaOH–urea concentration. RSM results showed that the optimal conditions are pretreatment time of 50 min, NaOH–urea concentration of 5.89%, and pretreatment temperature of −16 °C. AD was carried out under these conditions. The results showed that cumulative gas production for the control group was 231.5 ml whereas the biogas yield for best optimal conditions was 521.5 and 413 ml, respectively. In addition, AD reaction kinetics was evaluated by two mathematical kinetic models. It was found that modified Gompertz model is more suitable for describing the AD behavior.

中文翻译：

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NaOH-尿素预处理藻类生物质厌氧消化沼气

随着藻类废弃物的逐渐增多，其处置已成为海洋环境保护领域的关键问题。藻类生物质的厌氧消化 (AD) 是一种以有益方式对其进行处理的潜在方法。然而，藻类的 AD 受到了强大的弹性细胞壁的阻碍，因此，在 AD 之前对藻类生物质进行预处理是必不可少的过程。本研究以绿藻（浒苔）为研究底物，探讨NaOH-尿素预处理对生物量的破坏和影响。用扫描电镜和热重分析分析浒苔细胞壁结构的损伤通过NaOH-尿素预处理。响应面法(RSM)用于优化预处理条件以获得最佳实验条件。实验自变量是预处理时间、预处理温度和 NaOH-尿素浓度。RSM 结果表明，最佳条件是预处理时间为 50 min，NaOH-尿素浓度为 5.89%，预处理温度为 -16 °C。AD 在这些条件下进行。结果表明，对照组的累计产气量为 231.5 毫升，而最佳最佳条件下的沼气产量分别为 521.5 和 413 毫升。此外，AD 反应动力学通过两个数学动力学模型进行评估。发现修正的 Gompertz 模型更适合描述 AD 行为。