Recovery and recycling of phosphorous from aquatic ecosystems by use of the salt-tolerant green algae Dunaliella and chitosan

研究了利用耐盐绿色杜氏藻和壳聚糖对水生态系统中磷进行回收和循环利用的工艺。在控制条件下使用实验室培养物，研究了环境或操作因素对杜氏藻细胞中P含量的各种组合的影响。考察了培养温度、光照强度、CO_2浓度、培养液中P、NaCl、N、Ca^<2+>浓度等因素对该菌生长的影响。利用响应面法对实验系统中的影响因素以及藻类生长速率和磷含量的实测响应进行了建模和分析。该模型表明，在培养液中磷浓度较低的情况下，小球藻细胞内磷含量对预培养液中磷浓度有很强的依赖性。盐酸普鲁卡因对藻细胞的生长也有促进作用。在下一步中，从收获的藻细胞的物理-化学处理方面的P回收进行了研究。结果表明，Ca（OH）_2或Al_2（SO_4）_3处理藻细胞中的多聚磷酸盐，能有效地沉淀出磷酸盐。生物聚合物，天然甲壳素和壳聚糖，是不是那么有效的固体去除。需要进一步研究改性壳聚糖如铁壳聚糖的使用。

A basic study on the development of a recovery and recycling process for phosphorous (P) from aquatic ecosystems by use of the salt-tolerant green algae Dunaliella and chitosan was performed. The effects of various combinations of environmental or operational factors on P content in the Dunaliella cells were examined, using laboratory cultures under controlled conditions. The factors examined were the culture temperature, light intensity, CO_2 concentration in flushing gas, P, NaCl, nitrogen and Ca^<2+> concentration in the culture. The experimental system of the factors and the measured responses of algal growth rate and P content was modeled and analyzed based on the response surface method. The model obtained revealed that the intracellular P content in D.parva was highly dependent on the P concentration in the pre-culture medium in the case of the P concentration in the culture was relatively low. It was also found that procaine hydrochloride was useful to increase the growth of the algal cells. In the next step, the P recovery in terms of physico-chemical treatments from the harvested algal cells was studied. The results showed the Ca(0H)_2 or Al_2(SO_4)_3 treatment for the polyphosphates in the algal cells was effective to precipitate phosphate salt. The biopolymers, natural chitin and chitosan, were not so effective at solid removal. Further study on the use of modified chitosan such as iron chitosan will be required.