Caicedo J R, Espinosa C, Andrade M, Gijzen H
Engineering Faculty-Universidad del Valle, Cali, Colombia.
Water Sci Technol. 2002;45(1):83-9.
Duckweed based stabilization ponds, an alternative for wastewater treatment, are attracting a growing interest from researchers because they are basically a low cost technology, easy to built and operate, and produce tertiary quality effluents. Besides, this technology offers the possibility of resource recovery by producing high quality duckweed protein, which can be of further use. Since the technology is rather new, there are many aspects to be studied before its full-scale implementation. It is necessary to gain sound knowledge of the basic principles of the complex processes occurring in the system, as well as of the practical aspects of design and operation. The presence of a layer of duckweed on the surface is expected to produce different environmental and physicochemical conditions in the water from those found in conventional stabilization ponds. These environmental and physicochemical conditions affect both plant growth and biological treatment processes in the system, therefore it is important to determine their behavior in a duckweed system and how they can be affected by an anaerobic pretreatment. Continuous flow pilot plants composed of seven ponds in series were operated with artificial substrate under two different conditions: with anaerobic pretreatment and without anaerobic pretreatment. The flow was kept constant during the operation. Conditions such as pH, temperature, dissolved oxygen, alkalinity, conductivity, chemical oxygen demand, biochemical oxygen demand, total and ammonium nitrogen, nitrites and nitrates, and phosphorus were evaluated in the system under steady state conditions. The main conclusions from the study include the following: pH, temperature and oxygen profiles are more stable in duckweed ponds than in conventional stabilization ponds; anaerobic pretreatment has a significant effect on the oxygen concentration in the system and on the organic matter removal but not on the nutrient removal.
浮萍稳定塘作为一种污水处理的替代方案，正吸引着越来越多研究人员的关注，因为它们基本上是一种低成本技术，易于建造和运行，并且能产生三级水质的出水。此外，这项技术还提供了通过生产高质量浮萍蛋白进行资源回收的可能性，这种蛋白可作进一步利用。由于该技术相当新，在全面实施之前还有许多方面需要研究。有必要深入了解系统中发生的复杂过程的基本原理，以及设计和运行的实际方面。预计浮萍层的存在会使水中的环境和物理化学条件与传统稳定塘中的不同。这些环境和物理化学条件会影响系统中的植物生长和生物处理过程，因此确定它们在浮萍系统中的行为以及它们如何受到厌氧预处理的影响很重要。由七个串联池塘组成的连续流中试装置在两种不同条件下使用人工基质运行：有厌氧预处理和无厌氧预处理。运行期间流量保持恒定。在稳态条件下评估了系统中的pH值、温度、溶解氧、碱度、电导率、化学需氧量、生化需氧量、总氮和铵氮、亚硝酸盐和硝酸盐以及磷等条件。该研究的主要结论如下：浮萍塘中的pH值、温度和氧气分布比传统稳定塘更稳定；厌氧预处理对系统中的氧气浓度和有机物去除有显著影响，但对营养物去除没有影响。
