Evaluating the Hydraulic Effects of the Flow through and over the Submerged Biofilter Installed in Polluted Streams.

The problem of shortage in freshwater resources in many countries around the world has led to the use of unconventional water resources such as treated wastewater and agricultural drains water to bridge the gap between the demand and supply. However, the open nature of most agricultural drains and the spread of population cumulation around them has made them vulnerable to many organic and inorganic pollutants. One of the artificial methods used to enhance the self-purification process in polluted streams is submerged biofilters (SB). However, most of the previous studies focused on the efficiency of the biofilter to remove the pollutants, and there is a lack of studies on hydraulic changes. This study aims to assess the hydraulic effects of the submerged biofilter of star-shaped plastic media on water streams and develop a mathematical formula that could predict such effects. For this purpose, an experimental study was conducted with 60 total runs (30 for flow through biofilter and 30 for flow over biofilter), and dimensional analyses with multi-linear regression analysis were used to correlate different parameters that affect the flow through and over the biofilter. The mathematical relationships were developed to determine the changes in the upstream water level and that heading up in streams due to the use of the biofilter for both cases of flow. The results of the new formulas are very close to the experimental results, with (R2 = 0.89) for flow through the biofilter and (R2 = 0.993) for the flow over biofilter. In addition, the results were very close to other developed equations. The developed formulas were used to predict the upstream water depth (h1) by knowing the discharge (Q), length (L), and width (B) of the biofilter.

Improving the Hydraulic Effects Resulting from the Use of a Submerged Biofiter to Enhance Water Quality in Polluted Streams.

Water scarcity is one of the most serious problems facing many countries. In addition, water pollution could lose more water. A submerged biofilter (SB) is used to enhance the self-purification process in polluted streams. However, most previous studies have focused on the efficiency of SB to remove pollutants and there is a lack of studies investigating the hydraulic changes in streams. The current paper aimed to study the hydraulic effects of SB on the flow behavior in streams and how to improve it. An empirical equation for determining the flow rate through SB was developed. Different cases were studied to improve the hydraulic effects resulting from the use of SB. The effect of increasing SB length was tested using different SB lengths. The results showed that increasing the length increased the upstream water depth (h1) and relative heading up (h1/h2). In the second case, comparison between continuous and fragmented SB was tested. The results showed that a fragmented biofilter increased the upstream water depth and the relative heading up. Case three tested the effect of SB height. Different SB heights were tested with a fixed length and constant flow rate. The results revealed that the upstream water depth and relative heading up decreased when the biofilter height decreased. Case four tested the effect of SB with a fixed volume and constant flow rate. In this case, the length and height of SB were changed where the volume was fixed. The results showed that the relative heading up decreased when the SB height decreased and the length increased, which revealed that the SB height can improve the hydraulic impacts. Finally, the use of SB to improve the water quality in polluted streams led to an increase of the relative heading up, which can be reduced by decreasing the height of SB.