Table 2 Parameters and analytical methods for the evaluation of the fermentation material
From: Foam formation in full-scale biogas plants processing biogenic waste
Parameter | Sample pre-treatment | Analytical methods and instruments |
|---|---|---|
Total solids (TS) | O | DIN 12880 |
Volatile solids (VS) | O | DIN 12879 |
pH value | CE/S | Microprocessor pH meter pH 95 (WTW, Germany) |
VFA/TIC | CE/S | Titration method according to Nordmann [27] |
Ammonium-nitrogen (NH4-N) | F | DIN 38406 E5, Spektroquant® test kit (measuring range 0.01 to 3 mg/L NH4-N, Merck, Germany), photometric measurement with MultiLab P5 (WTW, Weilheim, Germany) |
Chloride | F | Spektroquant® test kit (measuring range 2,5 to 250 mg/L Cl−, Merck, Darmstadt, Germany), photometric measurement with SpektralPhotometer CADAS 200 (Dr. Lange, Düsseldorf, Germany) |
Volatile fatty acids (acetate, propionate, butyrate) | F | High-performance liquid chromatography (Shimadzu, Japan); detector: RID-10A; column: VA 300/7.8 Nucleogel Ion 300 OA; eluent: 0.01 N H2SO4 [28] |
TOC/IC/TC/TN | B/S | TOC-VCSH/CSN with a TN unit (Shimadzu, Japan) |
Crude protein | CA | Calculated according to Dumas method [29]: Crude protein = 6.25 × ([TN] – [NH4-N] – [NO3-N] – [NO2-N]) (The concentrations of nitrate- and nitrite-nitrogen were neglected due to their low concentration in the digestates as measured previously.) |
Water-soluble elements | F | Inductively coupled plasma atomic emission spectrometry ICP-AES (Spectroflame, Spectro Int., Kleve, Germany) |
Pattern of fatty acids | E | GC (System 5890 Series II GC, Hewlett-Packard, Wilmington, USA) after extraction according to Bligh and Dyer [20] and Morrison and Smith [21] |
Surface tension | CE | Drop volume tensiometer (Lauda TV T-1, Lauda Dr. R. Wobser GmbH and Co. KG, Lauda-Königshofen, Germany) |