The hydraulic retention time determines wastewater inflow rate (hydraulic loading as influent volume per hour). Influent wastewater is received and flow rate is measured using a Parshall flume. Results for turbidity reductions vary depending on the turbidity of the influent water. IMLR may be 200% to 400% the flow rate of influent wastewater (Q). In the first case, the influent wastewater to the pond to be desludged is closed. Some plants have enhanced treatment processes to target nitrogen removal from influent water. This is dependent on volume of solids in the influent and decomposition rate. Influent concentrations of PFAS can vary by orders of magnitude for specific media or applications. Hydrolysis of complex organic molecules occurs improving biodegradability of the influent of the B-stage. Next the influent is pumped through a flotation unit which removes floatable waste. They are effective in reducing BOD (biological oxygen demand) of influent untreated water. This ensures that influent organic matter will be treated with a correct concentration of microorganisms. Influent flows fall through the filter and are captured by the underdrain. Influent entry is from above the filter media. This is a list of ports of the North Sea and its influent rivers.