What is required for the stabilization of solids with lime in terms of pH maintenance duration?

The stabilization of solids with lime requires a minimum duration of 2 hours for effective pH maintenance. This extended timeframe is essential because it allows lime to react sufficiently with the organic and inorganic materials present in the solids. The increase in pH due to lime application helps in neutralizing pathogens and stabilizing volatile solids by reducing their activity and odorous compound release.

The chemical reactions involved in stabilization require time to reach an effective equilibrium. If the duration is shorter than 2 hours, there may not be enough time for the lime to fully penetrate and modify the structure and composition of the solids adequately. Effective stabilization ensures that the treated solids are safe for further handling or disposal and improves overall treatment efficiency.

Longer durations promote better structural changes and the precipitation of contaminants, making it critical to adhere to the recommended pH maintenance period. Thus, the choice of 2 hours is based on established norms in wastewater treatment practices.