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

利用耐盐绿藻杜氏藻和壳聚糖对水生生态系统中磷(P)进行了回收和循环利用的基础研究。在控制条件下，利用实验室培养，研究了环境或操作因素的各种组合对杜氏藻细胞P含量的影响。考察了培养温度、光照强度、冲洗气中CO_2浓度、培养物中P、NaCl、氮和Ca^<2+>浓度等因素。基于响应面法对影响藻类生长速率和磷含量的因素及实测响应的实验系统进行了建模和分析。建立的模型表明，在培养液中磷浓度较低的情况下，小蠊胞内磷含量高度依赖于预培养液中的磷浓度。同时发现盐酸普鲁卡因对藻细胞的生长有促进作用。下一步，从收获的藻细胞中进行物理化学处理，研究磷的回收。结果表明，Ca(0H)_2或Al_2(SO_4)_3处理海藻细胞中的多磷酸盐能有效地沉淀磷酸盐。生物聚合物，天然几丁质和壳聚糖，对固体去除效果不佳。改性壳聚糖（如铁壳聚糖）的应用有待进一步研究。

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.