Table 2. Results from Previous Experiments Measuring the Concentration of Viral Genetic Markers in the Solid and Liquid Fractions of Wastewater Matrices.

study	virus	wastewater matrix	sample processing	KF or Kd (mL·g–1)
Graham et al.15	SARS-CoV-2	paired wastewater influent and primary sludge samples	solid and liquid fractions were separated by centrifugation; the supernatant from influent samples was further processed using PEG precipitation method; viral concentrations (N1 and N2) were measured using RT-ddPCR	Kd: 350–3100
				calculated/reported as the solid-influent concentration ratio
Li et al.16	SARS-CoV-2	wastewater influent	solid and liquid fractions were separated by centrifugation; liquids were further processed using PEG precipitation method; viral concentrations (N1, N2, and E gene) were measured using qPCR	Kd: 4000–20,000
				calculated/reported as the solid–liquid concentration ratio
Kim et al.40	SARS-CoV-2	paired wastewater influent and primary sludge samples	solid and liquid fractions were separated using different processing techniques; viral concentrations (N1 and N2) were measured using RT-ddPCR	KF: 1000–100,000
				calculated using the Freundlich model; solid to influent ratio
Kim et al.31	SARS-CoV-2	wastewater collected from sewer network	solid and liquid fractions were separated by centrifugation; liquids were further processed using a 0.45 μm pore size filter; viral concentrations (N and S gene) were measured using RT-ddPCR	Kd: 8600, 16,000
				calculated/reported as the solid–liquid concentration ratio
Wolfe et al.41	influenza A	paired wastewater influent and primary sludge samples	solid and liquid fractions were separated by centrifugation; the supernatant from influent samples was further processed using PEG precipitation method; viral concentrations (N1 and N2) were measured using RT-ddPCR	Kd: 1000
				calculated/reported as the solid-influent concentration ratio
Mercier et al.2	influenza A	wastewater and primary sludge samples	solid and liquid fractions were separated by centrifugation and filtration using a 0.45 μm pore size filter; viral concentrations were measured in settled solids, suspended solids, and liquid fractions (supernatant) using RT-qPCR	authors only reported the percent of viral RNA adsorbed onto wastewater solids, Kd was not reported
Wolfe et al.19	Mpox	paired wastewater influent and primary sludge samples	influent samples were processed using an affinity-based capture method with magnetic hydrogel Nanotrap particles with enhancement reagent 1; primary sludge samples were centrifuged to obtain solids; viral concentrations were measured using RT-ddPCR	Kd: 1000
				calculated/reported as the solid-influent concentration ratio
Yin et al.20	adenovirus	primary and secondary sludge	solid and liquid fractions were separated by centrifugation; viral concentrations were measured in the liquid fraction (supernatant) using qPCR; viral concentrations in solids were estimated using a mass balance equation	KF: 37,000, 40,000
				calculated using the Freundlich model
Yang et al.11	MS2, Phi6, Phix174, T4	primary sludge	solid and liquid fractions were separated by centrifugation and filtration using a 0.22 μm pore size filter; viral concentrations were measured using qPCR	KF: 4.1 × 106, 5.4 × 105, 1.2 × 105, and 8.5 × 103 for Phi6, MS2, T4, and Phix174, respectively