Department of Natural Resources and Environmental Engineering, School of Agriculture, Shiraz University, Shiraz 71441-65186, Iran.
Department of Natural Resources and Environmental Engineering, School of Agriculture, Shiraz University, Shiraz 71441-65186, Iran.
Sci Total Environ. 2022 Jan 1;802:149988. doi: 10.1016/j.scitotenv.2021.149988. Epub 2021 Aug 28.
Microalgae such Chlorella vulgaris can effectively absorb nitrate and phosphate from contaminated water. This work characterized nitrate and phosphate removal from simulated agricultural runoff using C. vulgaris. Statistically designed experiments were used to model the following responses: (1) algal growth; (2) nitrate removal; (3) phosphate removal; (4) protein in the algal biomass; (5) chlorophyll content of the biomass; (6) the biomass phenolics content; and (7) the free radical scavenging antioxidant activity of the biomass. These response were modelled for the following key experimental factors: initial nitrate concentration in the simulated runoff (1080-3240 mg L, as NaNO), initial phosphate concentration (20-60 mg L, as KHPO), photoperiod (8-24 h of light/day) and culture duration (5-15 days). The validated models were used to identify the factor levels to maximize the various responses. Nitrate removal was maximized at 85.6% when initial nitrate and phosphate concentrations were 2322 mg L and 38 mg L (N:P atom ratio ≈ 125:1), respectively, with a 17.2 h daily photoperiod in a 13-day culture. Phosphate removal was maximized at 95% when the initial nitrate and phosphate concentrations were 1402 mg L and 56.7 mg L (N:P ≈ 51:1), respectively, with a 15.7 h daily photoperiod in a 14.7-day culture. At least ~14 h of a daily photoperiod and a ~11-day culture period were required to maximize all the studied responses. C. vulgaris is edible and may be used as animal feed. Nutritional aspects of the biomass were characterized. Biomass with more than 24% protein could be produced. Under the best conditions, the chlorophyll (potential food colorants) content of the biomass was 8.5% and the maximum level of total phenolics (antioxidants) in the biomass was nearly 13 mg gallic acid equivalent g.
微藻（如普通小球藻）可有效吸收污染水中的硝酸盐和磷酸盐。本工作使用普通小球藻对模拟农业径流中的硝酸盐和磷酸盐去除进行了特征描述。采用统计设计实验对以下响应进行了建模：（1）藻类生长；（2）硝酸盐去除；（3）磷酸盐去除；（4）藻生物质中的蛋白质；（5）生物质中的叶绿素含量；（6）生物质中总酚类物质的含量；（7）生物质的自由基清除抗氧化活性。针对以下关键实验因素对这些响应进行了建模：模拟径流中的初始硝酸盐浓度（1080-3240mgL，以 NaNO 计）、初始磷酸盐浓度（20-60mgL，以 KHPO 计）、光照周期（每天 8-24 小时）和培养时间（5-15 天）。对验证模型进行了使用，以确定可使各种响应最大化的因子水平。当初始硝酸盐和磷酸盐浓度分别为 2322mgL 和 38mgL（N：P 原子比≈125：1），光照周期为 17.2 小时/天时，硝酸盐去除率最高可达 85.6%，培养时间为 13 天。当初始硝酸盐和磷酸盐浓度分别为 1402mgL 和 56.7mgL（N：P≈51：1），光照周期为 15.7 小时/天时，磷酸盐去除率最高可达 95%，培养时间为 14.7 天。要使所有研究的响应达到最大化，至少需要每天 14 小时的光照和 11 天的培养周期。普通小球藻可食用，可作为动物饲料。对生物质的营养方面进行了特征描述。可生产出蛋白质含量超过 24%的生物质。在最佳条件下，生物质中的叶绿素（潜在的食用色素）含量为 8.5%，生物质中总酚类物质（抗氧化剂）的最高含量接近 13mg 没食子酸当量 g。
