Massachusetts Wastewater Practice Exam

The treatment process that generally requires pH adjustment as the initial step is typically associated with cyanide removal. In many instances, cyanide compounds can be toxic and difficult to treat effectively at a neutral pH. Adjusting the pH to a more alkaline level can enhance the efficiency of the treatment processes, such as oxidation or hydrolysis, used to degrade cyanides into less harmful substances.

In contrast, the other treatment processes like plating wastewater and sewage treatment do not universally require an initial pH adjustment. While pH control can be important during various stages of these treatments, it is not typically a prerequisite step. In plating wastewater, pH may be adjusted during certain operational phases but varies depending on the specific contaminants. Similarly, in sewage treatment, the pH can fluctuate based on the influent characteristics, but pH adjustment is often not the first step taken.

Thus, the emphasis on cyanide removal and the critical role of pH adjustment in ensuring safe and effective treatment helps clarify why this choice is correct.