Application of hydrodynamic cavitation to improve the biodegradability of mature landfill leachate

Abstract

In this study, the application of hydrodynamic cavitation to improve the biodegradability of mature landfill leachate was investigated. Three configurations of cavitation device were examined and operational parameters of the process were selected. The study indicated that the orifice plate with a 3/10mm diameter conical concentric hole, characterized by the cavitation number of 0.033, is a reasonable choice to ensure the enhanced biodegradability of mature leachate. Using such a configuration and maintaining 30 recirculation passes through the cavitation zone at inlet pressure of 7 bar, the highest increase of biodegradability index (BI) of approximately 22% occurred, i.e., from the value of 0.046 to 0.056. The FT-IR/PAS analysis confirmed a degradation of refractory compounds that typically prevail in mature leachate. An evaluation of energy efficiency was made in terms of the actual consumed energy measured by using the Kyoritsu KEW6310 Power Quality Tester. A cavitational yield of 9.8 mg COD kJ(-1) was obtained for the optimum configuration and 30 recirculation passes. Regarding energy efficiency, the application of 10 cavitation cycles appeared to be the most profitable. This was due to an almost threefold higher cavitational yield of 27.5 mg COD kJ(-1). However, the preferable option should be selected by considering a satisfactory effect in the biodegradability enhancement.

Potassium Ferrate (VI) as the Multifunctional Agent in the Treatment of Landfill Leachate

“…The obtained test results are comparable with the previous findings, especially for leachate from old landfills, for which a decrease in the value of pollution indicators was observed. Generally, in the case of pH-value values were 4-9.5 [4][5][6][7][8][9][10][11][12], for COD 100-84 300 mg O 2 /L [4, [13][14][15][16] and for TOC 40-13 610 mg/L. In addition, for TN and TP, the values were 350-4.370 mg/L and 1-655 mg/L, respectively [18,[24][25][26][27][28][29][30][31].…”

“…Nevertheless, depending on the age of the landfill (young < 5 years; medium 5-10 years; old > 10 years), the physicochemical composition of the leachate may vary [3,4]. According to the available data [4][5][6][7][8][9][10][11][12], the pH-value of the leachate varies in the range of 4-7.6, 6.9-9 and 8.1-9.5 for the leachate from young, medium and old landfills, respectively. In the case of COD and TOC, a decrease in the values of these indicators was observed according to the age of the landfills, and for COD they amounted to approx.…”

“…For this reason, various physicochemical and biological methods are used to treat the leachate. The landfill leachate could be treated with: ozone after coagulation treatment [7], ozonation [21], hydrodynamic cavitation [11], catalytic oxidation (by using Ni/Al 2 O 3 as the catalyst) by supercritical water oxidation [12], coagulation-flocculation, chemical coagulation and reverse osmosis system [13,30], hybrid coagulation-nanofiltration process [20], electrocoagulation [15], electrochemical oxidation [17], photoelectrochemical treatment in a continuous flow reactor [16], coagulation and Fenton reagent, UV, H 2 O 2 and UV/H 2 O 2 process [35][36][37].…”

Metagenomics Response of Anaerobic Ammonium Oxidation (anammox) Bacteria to Bio-Refractory Humic Substances in Wastewater

“…The control reactor was operated without HS-addition (defined as HS0), while the other two reactors were fed with 1 and 10 mg-HS•L −1 (defined as HS1 and HS10, respectively). The biological oxygen demand (BOD 5 )/chemical oxygen demand (COD) ratio of the HS was determined to be smaller than 0.02, indicating that the HS is a pool of recalcitrant organics for microbes [33].…”

Pollutant and Microorganism Removal From Water by Hydrodynamic Cavitation

“…Cavitation is defined as the phenomenon of formation, growth and subsequent collapse of microbubbles or cavities when the liquid encounter shrinking device in extremely small intervals of time (milliseconds), then release enormous energies [3,4]. When liquid passes through a constriction, such as orifice plates or venture tubes, the local pressure drops below the saturated vapor pressure of the liquid at the operating temperature [5,6]. This results in vaporization of the part liquid or escapes of the dissolved gas in liquid which can form bubbles stream or cavities [7].…”