Fig. 2: The low-quality effluent and sludge owing to lime passivation.

The final pH (a) and Ca concentration (b) of the effluents under increasing Ca/P dosing ratios in lime precipitation. c Images of lime-treated WAC wastewater. The product purity (d) and moisture content (e) of the obtained sludges from various Ca/P dosing ratios in lime precipitation. Data with error bars represented as mean ± s.d. (n = 3).