Since the wastewater purification process in constructed wetland was a complex and nonlinear state affected by many interactional factors,it was hard to establish exact mathematics model to carry out multi-factor analysis and determine best operation condition by traditional means.

In the wastewater purification system of varied organisms, wastewater is purified according to the metabolism of the food chain step by step.

Operational parameters of Orbal oxidation ditch process in one sewage purification plant;

Study progress in constructed wetland ecosystems for sewage purification;

Recent advances of sonochemical oxidation in sewage purification;

With diluted anaerobically pretreated wastewater from a pig farm and Spirodela oligorrhiza,TN,NH~+_4-N and NO~-_x-N removal pathways in shallow-water duckweed-based wastewater treatment systems were studied in summer and winter.

Utilising algae for sewage purification is a biotechnology of transforming sewage into re- sources.