Infrared wave analysis after hydrodynamic and acoustic cavitation as effective method of confirming sewage sludge destruction

Abstract

The efficiency of disintegration of sewage sludge cells microorganisms were characterized using biochemical parameters such as COD, phosphate, ammonium nitrogen and proteins. The investigated process was additionally assessed using the coefficient DD (Degree of Disintegration). It has been demonstrated that a 30-min of hydrodynamic and ultrasonic disintegration causes the soluble COD value increased about 300 mg /L and 190 mg /L (average), while the degree of disintegration reached 24% and 21%, respectively. The efficiency of sewage sludge hydrodynamic and ultrasonic disintegration was confirmed by increased release of phosphate (V) (from 4 to 54 mg PO³⁻ ₄/L and to 50 mg PO³⁻ ₄/L, respectively), ammonium nitrogen (from 1.5 to 4 mg N-NH⁺ ₄/L and to 3.5 mg N-NH⁺ ₄/L, respectively) and proteins (from 5 to 70 mg/L and to 60 mg/L, respectively). The effectiveness of surplus activated sludge disintegration was tested in the infrared spectrum. Changes in absorbance at the specified wavelength attest to a release of i.e., amines, amino acids, amide groups (proteins), phosphates, ammonium salts of carboxylic acid, etc. during disintegration time. Revealing these chemical groups in over-sludge liquids attests to a destructive influence of hydrodynamic and ultrasonic cavitation on activated sludge microorganisms and effective cells lysis.

Keywords:

• Acoustic cavitation
• degree of disintegration
• disintegration
• hydrodynamic cavitation
• infrared spectrum
• surplus activated sludge

Acknowledgments

This work was supported by the EU ROUTES project (contract no. 265156, FP7 2007-2013, THEME [ENV.2010.3.1.1-2] Innovative system solutions for municipal sludge treatment and management).