Abstract Continuous cultivations of the microalga Chlorella sorokiniana using 10-L flat-panel bioreactors were conducted at different pH levels and hydraulic retention times (HRT) under natural light conditions to accomplish the maximum algal yields and high nutrient removal from anaerobic digestion effluent (ADE) of aquatic macrophytes, which contained high concentrations of ammonium-nitrogen and phosphate-phosphorus, but less available magnesium (Mg). In subsequent experiments, Mg was enriched directly or indirectly by lowering the pH in the original ADE as source medium of a flow-through system to increase the amount of available Mg for algal growth. In the Mg-enrichment experiment, a constant maximum algal yield, 0.7 g dry-weight L−1, was obtained at HRT of 5 days, and removal efficiencies in both ammonium-nitrogen and phosphate-phosphorus were >94%. The pH-controlled experiment was conducted at HRTs of 5 and 10 days at two different pH levels (5.0 and 6.5) of the source ADE. Finally, similar algal yields and nutrient removals were obtained using source ADE at pH 6.5 and 10 days HRT as those in the Mg-enrichment experiment. We demonstrated that pH control in the source ADE through continuous cultivation at the relatively longer HRT can help to maximize algal yield and improve nutrient removal without Mg enrichment.

中文翻译：

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小球藻连续培养条件及水生植物厌氧消化出水中养分去除

摘要 使用 10 L 平板生物反应器在不同 pH 值和水力停留时间 (HRT) 下在自然光条件下连续培养微藻小球藻，以实现最大的藻类产量和厌氧消化流出物 (ADE) 的高营养去除。水生大型植物，其中含有高浓度的铵 - 氮和磷酸盐 - 磷，但可用镁（Mg）较少。在随后的实验中，通过降低作为流通系统源介质的原始 ADE 中的 pH 值来直接或间接富集镁，以增加藻类生长的可用镁量。在富镁实验中，在 5 天的 HRT 下获得了恒定的最大藻产量，0.7 g 干重 L-1，铵-氮和磷酸盐-磷的去除效率均大于 94%。pH 控制实验是在 5 天和 10 天的 HRT 下在两种不同的 ADE 源 pH 水平（5.0 和 6.5）下进行的。最后，在 pH 6.5 和 10 天 HRT 条件下使用源 ADE 获得了与镁富集实验相似的藻类产量和养分去除量。我们证明了通过在相对较长的 HRT 下连续培养来控制源 ADE 中的 pH 值有助于在不富集镁的情况下最大限度地提高藻类产量并改善养分去除。