利用膜-光生物反应器(MPBR)连续培养微藻去除海水养殖废水中营养盐的研究

Continuous Microalgae Cultivation in Aquaculture Wastewater by Membrane Photobioreactor (MPBR) for Nutrient Removal

以海水养殖废水为培养基质,在膜-光生物反应器(membrane photobioreactor,MPBR)中进行微藻的连续进出水培养,对微藻的生长情况和废水中氮磷营养盐的去除效果进行了研究。首先,将小球藻和衣藻接种于海水养殖废水中进行批次培养,两种微藻均表现出对海水养殖废水较好的适应性,实现了较快生长,比生长速率分别为0.29和0.26 d^(-1)。之后,将小球藻和衣藻分别接种到水力停留时间为1.0 d的MPBR中进行为期32 d的连续进出水培养。小球藻和衣藻的生物量生产速率分别为37.9和32.4 mg·L^(-1)·d^(-1),分别是批次培养中微藻指数生长阶段生物量生产速率的3.4倍和3.6倍。同时MPBR也实现了对海水养殖废水中氮磷营养盐的高效去除,小球藻MPBR和衣藻MPBR在稳定运行阶段对溶解性无机氮(DIN)的平均去除率分别达到93.9%和93.6%,其对溶解性无机磷(DIP)的平均去除率分别达到98.8%和99.0%。可见采用膜法连续培养方法既实现了光生物反应器内微藻的高效培养,同时也实现了对进水中氮磷营养盐的高效去除,另外废水在处理过程中的停留时间相比于传统批次培养得到了极大的缩短,这些都将有利于促进微藻培养方法在水产养殖业的废水处理和循环使用中发挥更大的作用。

In this study, microalgae were cultured in saline aquaculture wastewater by membrane photobioreactor (MPBR) operated in continuous flow mode for algal biomass production and nutrient removal. Chlorella vulgaris and Chlamydomonas reinhartii were firstly batch cultured in saline aquaculture wastewater. C. vulgaris and C. reinhartii showed better adaptability of saline aquaculture wastewater to achieve the specific growth rates of 0.29 and 0.26 d^-1, respectively. Thereafter, C. vulgaris and C. reinhartii were inoculated into MPBR operated with hydraulic retention time (HRT) of 1.0 d for 32 days continuous flow cultivation. The algal biomass productivities achieved throughout the continuous flow cultivation were 37.9 and 32.4 mg·L^-1·d^-1 for the MPBR cultured with C. vulgaris and the MPBR cultured with C. reinhartii, respectively, which were 3.4-fold and 3.6-fold larger than that achieved throughout the batch cultivation, respectively. At the same time, advanced nutrient removal from saline aquaculture wastewater was also achieved in MPBR. The average reductions in dissolved inorganic nitrogen(DIN) throughout the continuous flow cultivation were 93.9% and 93.6% for the MPBR cultured with C. vulgaris and the MPBR cultured with C. reinhartii, respectively. The average reductions in dissolved inorganic phosphorus(DIP) were founded to be 98.8% for the MPBR cultured with C. vulgaris and 99.0% for the MPBR cultured with C. reinhartii. Therefore, it can be seen that using the membrane technology to culture microalgae in continuous flow mode not only realized the efficient production of algal biomass in the photobioreactor, but also realized the efficient removal of nitrogen and phosphorus from the wastewater. Compared with the traditional batch culture mode, continuous culture in MPBR greatly reduced the residence time of wastewater needed for the microalgae cultivation and nutrient removal. All these will play a great role in favor of promote the microalgae culture mode in aquaculture wastewater treatment and recycling.