What issue may arise from using too much polymer in a belt filter press?

Using too much polymer in a belt filter press can lead to belt blinding, which is the correct answer. When polymer is applied excessively, it can cause the filter belt's surface to become clogged with particles that are bound together too tightly. This impedes the movement of water and solids through the filter, reducing the efficiency of the dewatering process. When the belt becomes blinded, it can lead to inadequate solids separation, resulting in poor performance of the press and potentially leading to the need for cleaning or even replacement of the filter media.

Other issues such as increased flow rates, higher BOD levels, and pumping failures are less directly related to using an excessive amount of polymer. Heavy polymer usage may not necessarily increase flow rates; instead, it tends to reduce the ability of the system to effectively process the sludge. Similarly, higher BOD levels are typically a result of increased organic load rather than polymer application itself. As for pumping failures, while they can occur due to various operational issues, they are not a direct result of polymer use. Thus, the most pertinent and significant issue from using too much polymer in a belt filter press is indeed belt blinding.