Thiết kế Cơ sở vẫn như nhau, nhưng nồng độ tăng lên đáng kể như dòng chảy giảm. May mắn thay, trong trường hợp này hệ thống đất ngập nước đã đủ mạnh mẽ để thích ứng với thay đổi và vẫn đạt được mục tiêu. Những giai thoại phục vụ thông báo rằng cơ sở của thiết kế phải được cẩn thận đặt ra, và thay đổi hợp lý dự kiến trong dòng chảy và tải chảy đến. | 16 Design Basis The preliminary step in the design of a treatment wetland is to acquire a fundamental understanding of the site of the wetland. Site conditions dictate the physical chemical and biological environment of a wetland treatment system. Conditions that should be evaluated during planning of a wetland treatment system include climate geography groundwater and its chemistry soils and geology rainfall and runoff water chemistry biology and socioeconomic factors. The importance of each of these conditions may vary but all should be investigated to some extent. Detailed studies may be needed to determine the importance of those site conditions that affect technical feasibility. This book primarily considers performance-based design algorithms. The first steps in the process require the assembly of the basis of the design which includes the following steps 1. Determine inlet concentrations and flows. 2. Determine target concentrations regulatory limits and allowable exceedance factors . 3. Determine allowable inflow and seepage rates. 4. Determine rain ET and temperature ranges for the project site. 5. Select wetland type FWS or SSF . Often the establishment of flows and concentrations will require the acquisition of data on flows and concentrations at least to confirm estimates based on prior operations or knowledge of the technology of the source. There are unfortunately numerous examples of inappropriate selection of the design basis for treatment wetlands. The difficulty is often not the misunderstanding of current conditions but rather incorrect assumptions about future conditions. This may involve actions outside the control of the designer. For instance the failed Gustine California system added wetlands to existing lagoons Walker and Walker 1990 . The source water was a combination of municipal and milk processing wastewaters the latter having very high biochemical oxygen demand BOD . The design presumption was that milk wastewater would be .
