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• W2299688568 abstract "The activated sludge process (ASP) is a widely applied technology for biological wastewater treatment. The sludge production from the ASP is enormous and its management contributes typically 30 - 50% of the total operating costs of the wastewater treatment plant (WWTP). To develop a more cost-effective and sustainable wastewater treatment process, reduced sludge generation, improved energy recovery and beneficial biosolids reuse for nutrient recovery are key optimisation targets. Anaerobic digestion (AD) is widely adopted for sludge stabilisation and energy recovery through biogas production. However, the poor digestibility of sludge, especially waste activated sludge (WAS), often reduces the AD efficiency. Sludge application on agricultural land provides an opportunity for the beneficial reuse of organic matter and nutrients, particularly nitrogen and phosphorus. However, toxic metal contaminants, including Cd, Cr, Cu, Ni, Pb and Zn, often limit land application of these biosolids. Hence there is a significant demand for innovative sludge treatment solutions that can remove toxic metals and improve sludge digestibility to maximise the beneficial reuse potential and minimise costs related to transportation and disposal. In this thesis, a novel sludge treatment technology concept was developed with integrating nitrite addition and in situ electrochemical acid and alkali production, whereby metal removal, pathogen reduction, sludge digestibility and dewaterability were all enhanced at the same time. First, the effect of nitrite addition on metal removal from acidified sludge was investigated using WAS from three different full-scale WWTPs. It was found that acidification to pH 2 by sulfuric acid achieved Zn removal of around 70%, but only 3 - 7% of Cu was removed. Nitrite addition of 20 mg NO2--N/L (equal to 19.2 mg HNO2-N/L) to the acidified WAS substantially enhanced Cu removal to 45-64%, while Zn removal was also increased to over 81%. Metal distribution analysis using sequential chemical extraction revealed that the improvement of Cu and Zn removal was mainly due to the release of the organically bound metal fraction. Subsequent process optimisation demonstrated that a nitrite addition of 10 mg NO2--N/L and 5 hour exposure time was sufficient for metal removal enhancement for WAS at pH 2. To avoid the purchase, transport, storage and handling of corrosive acid and alkali for the treatment as well as minimising possible occupational health and safety issues with the treatment, a three-compartment electrochemical system (ES) was employed for the in situ sludge acidification and alkali generation. Acidification (to pH 2) of WAS and alkali production were achieved in the anode and cathode compartment, respectively, with a current efficiency of 85% for both anode and cathode processes. Maintaining the optimised WAS treatment conditions (5 h at pH 2 with 10 mg NO2--N/L) achieved solubilisation of 60 ± 2% Cu and 86 ± 1% Zn, which is even higher than what was achieved in the treatment with external acid dosing. After separation of the solids by centrifugation, the metal-laden sludge liquor could be treated further in the cathodic process where the in situ generated alkali could be used to remove 74 ± 1% of Cu and 100% of Zn by precipitation. To evaluate the effect of acidification with nitrite treatment on the digestibility of the treated sludge, biochemical methane potential (BMP) tests were conducted. WAS acidified to pH 2 by HCl dosing or electrochemical acidification was exposed to the optimised nitrite treatment, followed by removal of the solubilised metals by alkali precipitation. Compared to the untreated WAS, the methane production of the WAS treated by HCl or electrochemical acidification was increased by 46 ± 3% and 55 ± 6% through 69 days of BMP tests, respectively. By fitting the experimental data to a first-order kinetic model, the biochemical methane potential of WAS from the treatment by electrochemical acidification with nitrite and metal removal was estimated as 474 L CH4/kg VS. Compared with the biochemical methane potential of 232 L CH4/kg VS for the untreated WAS, this represents a very significant improvement of the WAS digestibility. Furthermore, the solids content of (laboratory-scale) belt filter dewatered sludge after treatment was increased from 14.6% to about 19%, which is again a very substantial and valuable improvement. Furthermore, a 4-log reduction in the concentration of two selected pathogen indicators, total coliforms and E.coli, was achieved in the WAS treated by acidification with nitrite addition. A further application of the acid/nitrite method for the treatment of primary sludge was also evaluated. Only the electrochemical acidification method achieved a significant metal solubilisation (39 ± 1% and 82 ± 1% for Cu and Zn, respectively), but it had only a minor effect on the digestibility and dewaterability, both of which are typically quite high already for primary sludge. At last, the economic potential of this novel sludge treatment technology concept was evaluated using a cost analysis based on the achieved research outcomes. The major economic benefits could be generated from reduced sludge production (through enhanced digestibility and dewaterability) and improved sludge quality (due to the decrease of toxic metal and pathogen concentrations). With both capital and operational cost considered, the electrochemical treatment with nitrite addition was estimated to be able to achieve a net benefit in 7 and 4 years for the sludge treatment with and without AD, respectively. Overall, this study has clearly demonstrated the technical feasibility and economic potential of an innovative new sludge pre-treatment method that is able to achieve significantly improved metal removal, pathogen reduction, sludge digestibility and dewaterability through a relatively simple, single stage treatment process involving acidification by ES and nitrite addition." @default.
• W2299688568 created "2016-06-24" @default.
• W2299688568 creator A5059277612 @default.
• W2299688568 date "2015-12-03" @default.
• W2299688568 modified "2023-09-23" @default.
• W2299688568 title "Novel sludge treatment technology enhances toxic metal removal, pathogen reduction, sludge digestibility and dewaterability" @default.
• W2299688568 cites W1492025590 @default.
• W2299688568 cites W1539839337 @default.
• W2299688568 cites W1540404708 @default.
• W2299688568 cites W1548650423 @default.
• W2299688568 cites W1575253570 @default.
• W2299688568 cites W1602946632 @default.
• W2299688568 cites W1856219842 @default.
• W2299688568 cites W1917372497 @default.
• W2299688568 cites W1966984375 @default.
• W2299688568 cites W1967498598 @default.
• W2299688568 cites W1969373222 @default.
• W2299688568 cites W1970091067 @default.
• W2299688568 cites W1973871727 @default.
• W2299688568 cites W1973890341 @default.
• W2299688568 cites W1976344205 @default.
• W2299688568 cites W1977662170 @default.
• W2299688568 cites W1979290418 @default.
• W2299688568 cites W1980144827 @default.
• W2299688568 cites W1980950024 @default.
• W2299688568 cites W1981002830 @default.
• W2299688568 cites W1983872796 @default.
• W2299688568 cites W1994044024 @default.
• W2299688568 cites W1994812618 @default.
• W2299688568 cites W1995527010 @default.
• W2299688568 cites W1996423265 @default.
• W2299688568 cites W1997389217 @default.
• W2299688568 cites W1997720395 @default.
• W2299688568 cites W1998815067 @default.
• W2299688568 cites W1999836109 @default.
• W2299688568 cites W1999851629 @default.
• W2299688568 cites W2003423793 @default.
• W2299688568 cites W2004452659 @default.
• W2299688568 cites W2005156563 @default.
• W2299688568 cites W2014163601 @default.
• W2299688568 cites W2014647685 @default.
• W2299688568 cites W2017063371 @default.
• W2299688568 cites W2020783385 @default.
• W2299688568 cites W2024739977 @default.
• W2299688568 cites W2025187230 @default.
• W2299688568 cites W2028621974 @default.
• W2299688568 cites W2028886596 @default.
• W2299688568 cites W2030187888 @default.
• W2299688568 cites W2032107190 @default.
• W2299688568 cites W2036332789 @default.
• W2299688568 cites W2036574651 @default.
• W2299688568 cites W2038031723 @default.
• W2299688568 cites W2040315921 @default.
• W2299688568 cites W2041141901 @default.
• W2299688568 cites W2042559508 @default.
• W2299688568 cites W2042572782 @default.
• W2299688568 cites W2044090624 @default.
• W2299688568 cites W2044659623 @default.
• W2299688568 cites W2044851096 @default.
• W2299688568 cites W2047735969 @default.
• W2299688568 cites W2047765871 @default.
• W2299688568 cites W2049032268 @default.
• W2299688568 cites W2049159561 @default.
• W2299688568 cites W2050015812 @default.
• W2299688568 cites W2052393515 @default.
• W2299688568 cites W2053477819 @default.
• W2299688568 cites W2054963520 @default.
• W2299688568 cites W2055883700 @default.
• W2299688568 cites W2056047987 @default.
• W2299688568 cites W2058172088 @default.
• W2299688568 cites W2062123032 @default.
• W2299688568 cites W2063069479 @default.
• W2299688568 cites W2063294656 @default.
• W2299688568 cites W2065409754 @default.
• W2299688568 cites W2066580653 @default.
• W2299688568 cites W2070246701 @default.
• W2299688568 cites W2071437625 @default.
• W2299688568 cites W2071725160 @default.
• W2299688568 cites W2073239598 @default.
• W2299688568 cites W2073537292 @default.
• W2299688568 cites W2073548842 @default.
• W2299688568 cites W2073565713 @default.
• W2299688568 cites W2075069674 @default.
• W2299688568 cites W2075484742 @default.
• W2299688568 cites W2076412587 @default.
• W2299688568 cites W2086906631 @default.
• W2299688568 cites W2087251363 @default.
• W2299688568 cites W2087539273 @default.
• W2299688568 cites W2088730211 @default.
• W2299688568 cites W2088820729 @default.
• W2299688568 cites W2089225020 @default.
• W2299688568 cites W2089487971 @default.
• W2299688568 cites W2089848749 @default.
• W2299688568 cites W2092658731 @default.
• W2299688568 cites W2093790008 @default.
• W2299688568 cites W2111641049 @default.
• W2299688568 cites W2113536011 @default.
• W2299688568 cites W2115070974 @default.
• W2299688568 cites W2118854147 @default.
• W2299688568 cites W2125711856 @default.

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