Analysis of Reject Water Formed in the Mechanical Dewatering Process of Digested Sludge Conditioned by Physical and Chemical Methods

Beata Bień and Jurand D. Bień
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Beata Bień: Faculty of Infrastructure and Environment, Czestochowa University of Technology, 42-200 Czestochowa, Poland
Jurand D. Bień: Faculty of Infrastructure and Environment, Czestochowa University of Technology, 42-200 Czestochowa, Poland

Energies, 2022, vol. 15, issue 5, 1-14

Abstract: Reject water separated from digested sludge may be a potential source of nutrients due to its high content. However, most often, reject water after sludge dewatering is directed to sewage lines at wastewater treatment plants, negatively affecting their operation, especially in the biological part. The activities related to sludge conditioning before dewatering have a direct impact on the quality of the reject water. The reject water of raw digested sludge is characterized by very high concentrations of ammonium nitrogen, at 1718 mgN-NH 4 + /dm 3 ; phosphates, at 122.4 mgPO 4 3− /dm 3 ; and chemical oxygen demand (COD), at 2240 mgO 2 /dm 3 . The objective of the research was to determine the impact of selected sludge conditioning methods on the quality of reject water obtained after sludge dewatering. The following parameters were analyzed in the reject water: the chemical oxygen demand (COD), phosphates, ammonium nitrogen, and total suspended solids (TSS). It has been observed that the sludge sonification process increases the content of impurities (COD, phosphates) in reject water with an increase in the amplitude of the ultrasonic field. On the other hand, the chemical reagents cause a decrease in the concentration of the pollutants with an increase of the chemical dose. It has been found that the inorganic coagulant PIX 113 gives much better results regarding the reduction of contamination than the polyelectrolyte Zetag 8180.

Keywords: reject water; quality; sewage sludge; conditioning; sonification (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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