# Efficiency of Chemical Toilet Sewage (CTS) Co-Fermentation with Typical Energy Crops
## 2 Materials and Methods
### Materials  
Maize (_Zea mays_) silage maintained and stored in a pile system was sourced from the crops of the Teaching & Research Station of the University of Warmia and Mazury in Olsztyn. The station itself is sited in the village of Baldy (Poland). The anaerobic sludge used to inoculate the anaerobic reactors was sourced from a biogas plant used to process maize silage and cattle slurry. The key running parameters for the biogas plant were: T = 38 \({}^{\circ}\)C, OLR = 2.2 kgVS/m\({}^{3}\cdot\)day, HRT = 20 days, and initial feedstock water content = 90%. Accordingly, the anaerobic sludge did not have to be adapted prior to the experiment proper. The basic parameters of the maize silage and anaerobic sludge are presented in Table 1.  
The CTS used in the experiments was sourced from the sewage collection station of the \"Korektywa\" shipping port in the town of Piaski (near Ruciane-Nida). The CTS profile is given in Table 2.  
The process was designed to match the running conditions at the agricultural biogas plant from which the anaerobic sludge was obtained (this obviated the need to adapt the anaerobic sludge inoculums). Before being fed into the anaerobic reactors, the mixture of maize silage and tap water + CTS (90% water content) was ground and homogenized in a T65 MultiDrive Control laboratory mill (IKA, Germany). The feedstock particles averaged 2.0 \(\pm\) 1.0 mm in size. The process parameters and volumes of organic feedstocks used in the experiment are given in Table 3.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & **Unit** & \multicolumn{2}{c}{**Value**} \\ \hline pH & pH & 8.05 \(\pm\) 0.74 \\ \hline BOD\({}_{5}\) & mg O\({}_{2}\)/dm\({}^{3}\) & 4645 \(\pm\) 330 \\ \hline COD & mg O\({}_{2}\)/dm\({}^{3}\) & 13860 \(\pm\) 920 \\ \hline TOC & mg O\({}_{2}\)/dm\({}^{3}\) & 10350 \(\pm\) 270 \\ \hline TN & mg N\({}_{\text{total}}\)/dm\({}^{3}\) & 2240 \(\pm\) 230 \\ \hline Organic nitrogen & mg N/dm\({}^{3}\) & 2150 \(\pm\) 240 \\ \hline Ammoniacal nitrogen & mg N-NH\({}_{4}\)/dm\({}^{3}\) & 90 \(\pm\) 50 \\ \hline Nitric nitrogen & mg N-NO\({}_{3}\)/dm\({}^{3}\) & 2.20 \(\pm\) 0.93 \\ \hline Nitrite nitrogen & mg N-NO\({}_{2}\)/dm\({}^{3}\) & 0.12 \(\pm\) 0.02 \\ \hline TP & mg P\({}_{\text{total}}\)/dm\({}^{3}\) & 202 \(\pm\) 61 \\ \hline Orthophosphates & mg P-PO\({}_{4}\)/dm\({}^{3}\) & 129 \(\pm\) 33 \\ \hline Dry residue & mg/dm\({}^{3}\) & 12.5 \(\pm\) 2.2 \\ \hline Chlorides & mgCl\({}^{-}\)/dm\({}^{3}\) & 574 \(\pm\) 62 \\ \hline Sulfates & mgSO\({}_{4}\)/dm\({}^{3}\) & 0.39 \(\pm\) 0.12 \\ \hline Lipids & mg/dm\({}^{3}\) & 184 \(\pm\) 36 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Profile of the chemical toilet sewage used in the experiment.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & & \multicolumn{2}{c}{**Value**} \\ \cline{3-4}
**Parameter** & **Unit** & \multicolumn{2}{c}{**Maize Silage**} & \multicolumn{2}{c}{**Anaerobic**} \\  & & & **Sludge** \\ \hline Dry matter (TS) & \% & 30.2 \(\pm\) 0.8 & 9.8 \(\pm\) 0.2 \\ Organic dry matter (VS) & \% TS & 89.0 \(\pm\) 0.6 & 68.5 \(\pm\) 2.5 \\ Minerel dry matter (MS) & \% TS & 11.0 \(\pm\) 1.3 & 31.5 \(\pm\) 2.5 \\ Total nitrogen (TN) & mg/g TS & 11.1 \(\pm\) 0.9 & 33.1 \(\pm\) 3.3 \\ Total phosphorus (TP) & mg/g TS & 2.4 \(\pm\) 0.3 & 1.7 \(\pm\) 0.2 \\ Total carbon (TC) & mg/g TS & 460 \(\pm\) 13 & 309 \(\pm\) 28 \\ Total organic carbon (TOC) & mg/g TS & 441 \(\pm\) 15 & 199 \(\pm\) 34 \\ C\(\cdot\)N ratio & - & 39.6 \(\pm\) 1.6 & 9.3 \(\pm\) 0.1 \\ pH & - & 7.73 \(\pm\) 0.08 & 7.21 \(\pm\) 0.31 \\ Protein & \% TS & 9.2 \(\pm\) 0.6 & 20.7 \(\pm\) 2.8 \\ Lipids & \% TS & 2.2 \(\pm\) 0.5 & 3.1 \(\pm\) 0.5 \\ Sugars & \% TS & 60.4 \(\pm\) 1.0 & 1.6 \(\pm\) 0.4 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Profile of the maize silage and anaerobic sludge.