I wish to know about the reason behind getting VFA values in negative. Initially for few days, I got positive values (91mg/L to 13.61 mg/L) and for the past two days my values went to -20.09 and -15 mg/l. what could be the possible reason for negative values. The sample is from digested wastewater samples.
I use three point titration method using 0.1 N H2SO4 by following Kapp et al method.
Total VFA [mg L-1] = [131,340 * (VpH4.0 – VpH5.0) * NH2SO4 / V sample] – [3.08 * VpH4.3*NH2SO4/ V sample *1,000] – 10.9
VpH4.0 Volume of added acid until pH=4.0 in mL
VpH4.3 Volume of added acid until pH=4.3 in mL
VpH5.0 Volume of added acid until pH=5.0 in mL
V sample Volume of titration sample (recommended 20 mL)
NH2SO4 Normality of used acid (0.1 in case of 0.05 mol L-1 sulphuric acid)
Ref: KAPP, H. (1984). Schlammfaulung mit hohem Feststoffgehalt. Stuttgarter Berichte zur Siedlungswasserwirtschaft, Bd. 86, Oldenbourg Verlag, München.
Your reply /suggestions regarding this highly appreciated.
I have not any expertise on this matter, but I can introduce Iranian experts.
- Badges
- Science topic
- Similar topics
- Biological Science
- Biochemistry
- Biochemical Techniques
- Analytical Chemistry
- pH