What percentage of solids should be wasted each week in the summer from a package wastewater treatment plant for optimal quality?

Wasting 5% of solids each week during the summer from a packaged wastewater treatment plant is optimal for maintaining the quality of the effluent. In summer months, higher temperatures can accelerate biological processes, leading to increased microbial activity and consequently higher production of biomass in the system. If too few solids are removed, there is a risk of overloading the system with organic material, which can result in deterioration of treatment efficiency and poor effluent quality.

Wasting at the 5% level strikes a balance, ensuring that sufficient biomass is removed to prevent this overload while retaining enough microorganisms to sustain effective treatment. This percentage supports optimal conditions for the biological processes taking place within the treatment plant, helps in stabilizing the microbial population, and allows the treatment system to operate efficiently.

In contrast, other percentages might either remove too few solids, risking system overload, or remove too many, which could lead to a reduction in the overall treatment capacity and performance. Thus, the choice of 5% represents a scientifically backed approach for encouraging high-quality wastewater treatment, particularly during the summer months when conditions are more conducive to rapid biological growth.