Release of N-containing compounds during pyrolysis of milk/dairy processing sludge - Experimental results and comparison of measurement techniques Articles uri icon

authors

  • Kwapinska, Marzena
  • Sommersacher, Peter
  • Kienzl, Norbert
  • Retschitzegger, Stefan
  • Lagler, Jacqueline
  • HORVAT, ALEN
  • Leahy, James J.

publication date

  • March 2024

start page

  • 1

end page

  • 13

issue

  • 106391

volume

  • 178

International Standard Serial Number (ISSN)

  • 0165-2370

Electronic International Standard Serial Number (EISSN)

  • 1873-250X

abstract

  • A dried dairy processing sludge (sludge from wastewater treatment of an effluent from a milk processing plant)
    was pyrolysed in a single-particle reactor at different temperatures from 400 ◦C to 900 ◦C. NH3 and HCN were
    measured online and offline by means of FTIR as well as by cumulative sampling in impinger bottles (in 0.05 M
    H2SO4 and 1 M NaOH, respectively) and analysed by photometric method. NO and NO2 were measured online
    using a nitric oxide analyser while N2O was measured by FTIR. Nitrogen (N) in the sludge and in the remaining
    char, char-N, was determined. Moreover, tar content in pyrolysis gas was measured and tar-N was determined.
    The results with respect to N mass balance closure are discussed. The different measurements techniques are
    compared. For pyrolysis at 520 ℃ and 700 ℃ nitrogen in the gas phase was mainly contained as N2 (36 % and 40
    % respectively), followed by NH3 (15 % and 18 %), tar-N (10 % and 9 %), HCN (1 % and 3 %), NO (1 %) and NO2
    (0.2 %). The dairy processing sludge has very specific properties with organic-N present predominantly as
    proteins and a high content of inherent Ca. These characteristics affected the distribution of N. The amount of
    char-N was higher while the amount of tar-N lower than for sewage sludge from literature, at comparable pyrolysis temperature.

subjects

  • Chemistry
  • Food Science and Technology
  • Nuclear Energy

keywords

  • ammonia; hydrogen cyanide; n mass balance; char; ftir; photometric