Organics removal of combined wastewater through shallow soil infiltration treatment: A field and laboratory study

COD Removal Model and Its Application in Shallow Soil Infiltration Treatment System

“…And biological COD removal, affected more by temperature, might be predominant in the three SSIT systems with packing media (T2, T3 and T4), which has been manifested by our additional experiments 18) . The f and m values in Table 4 showed that the effects of q and S0 on COD removal relied on the packing medium being used in SSIT system.…”

“…1). Four trenches (labeled as T1, T2, T3 and T4) were designed in parallel, with total and effective depth about 0.5 m and 0.3 m, respectively 18) . Different artificial soil constituents used in the four different SSIT systems are listed in Table 1.…”

“…In SSIT systems, abiological effect was evident and contributed to 28.1%-42.3% of the total COD removal, which increased with the increase of water temperature 18) . COD, more convenient and easier to determine than BOD, is always used to measure the total organics in wastewater.…”

“…At first, the 1.035 in Model 2 was used for BOD removal and the effect of temperature on COD removal might be different due to the fact that a substantial portion (28.1%-42.3%) of COD removal is contributed by abiological proceses 18) . Thus considering the impact of temperature on COD removal and the difference existed among the four SSIT systems, the Model 2 is rewritten as Model 3,…”

“…), and partly from the shallow depth of soil matrix. In addition, the abiological degradation contributed to 28.1%-42.3% of the total COD removal 18) , which has been included in the integrated COD removal model while always not in BOD removal models (e.g., Eckenfelder Model). This disagreement phenomenon between SIT and SSIT systems needs more detailed investigation before really adequate conclusion could be deduced.…”