Dosing free nitrous acid for sulfide control in sewers: Results of field trials in Australia

Jiang, Guangming; Keating, Anthony; Corrie, Shaun; O’Halloran, Kelly; Nguyen, Lam; Yuan, Zhiguo

doi:10.1016/j.watres.2013.05.024

Cited by 103 publications

(38 citation statements)

References 27 publications

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“…FNA dosing at 0.2 -0.3 mg HNO 2 -N/L for 12 to 24 hours was shown to be able to suppress hydrogen sulfide and methane formation in anaerobic sewers for several days to weeks [10,12,13]. Field trials in real sewers confirmed these results [14] and cell viability tests revealed that FNA treatment of sewer biofilms incurred a substantial loss (85-95%) of cell viability [10]. Pijuan et al [11] applied FNA to treat secondary activated sludge and observed that FNA at 1-2 mg HNO 2 -N/L entirely deactivated secondary sludge and was able to significantly improved its biodegradability.…”

Section: Introductionmentioning

confidence: 71%

“…This represents an ample supply of renewable FNA that could be applied onsite for sludge treatment [33,34] or transported upstream for sewer applications [14].…”

Section: Economic Assessment For Fna Productionmentioning

confidence: 99%

“…Such strategies require intensive energy input and/or significant amounts of chemicals, and often only targets the symptoms rather than eliminating the biofilm. Due to the potency of FNA as a biocidal agent, 12-hr dosage of FNA at concentrations of 0.2-0.3 mg HNO 2 -N/L every five days can effectively decrease the sulfide production and emission in sewer systems by over 80% [13,14]. This can substantially reduce the amount of chemicals required compared to conventionally used chemicals such as oxygen, nitrate, ferric/ferrous salts and magnesium hydroxide, which need to be added continuously rather than intermittently.…”

Section: Potential Applications Of Fna As a Biocidal Agent For Wastewmentioning

confidence: 99%

See 2 more Smart Citations

Producing free nitrous acid – A green and renewable biocidal agent – From anaerobic digester liquor

Law

Wang

et al. 2015

Chemical Engineering Journal

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101

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Recent studies have shown that free nitrous acid (FNA) at parts per million is strongly biocidal to a broad range of microorganisms involved in wastewater management. Applications have been developed, where FNA is used to deactivate anaerobic sewer biofilms thus suppressing sulfide and methane production in sewers, or to lyse secondary sludge resulting in reduced sludge production and enhanced biogas production. This study examines the feasibility of producing FNA from a waste stream namely the anaerobic sludge digestion liquor, thus providing a source of FNA for the above applications within wastewater systems. Complete nitritation was achieved in a lab scale sequencing batch reactor (SBR) treating reject wastewater. Under stable operation, the system sustained more than 90% conversion of the 1.0 and 0.8 g NH 4 + -N/L contained in the synthetic and real digester liquor, respectively, to nitrite. Each liter of this nitrite rich effluent 2 could be acidified to pH 2 with only 66 mmole of H + , due to the low level of alkalinity in the effluent. This converts almost all of the nitrite to FNA providing an ample source of FNA for sewer and sludge pretreatment applications. Despite the high nitrite concentration in the reactor, minimal N 2 O was produced with an emission factor of 0.08% of the ammonium nitrogen converted. Finally, an economical assessment of a theoretical full-scale installation for FNA production was conducted and compared with the costs of producing this FNA from a commercial nitrite supply.

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Section: Introductionmentioning

confidence: 71%

“…This represents an ample supply of renewable FNA that could be applied onsite for sludge treatment [33,34] or transported upstream for sewer applications [14].…”

Section: Economic Assessment For Fna Productionmentioning

confidence: 99%

Section: Potential Applications Of Fna As a Biocidal Agent For Wastewmentioning

confidence: 99%

See 1 more Smart Citation

Producing free nitrous acid – A green and renewable biocidal agent – From anaerobic digester liquor

Law

Wang

et al. 2015

Chemical Engineering Journal

Self Cite

101

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show abstract

“…FNA dosing at 0.26 mg-N/L for 12 h was adequate to completely suppress methanogenesis in the sewer reactor, with only 20% recovery of methane production occurring in the following two weeks. This cost-effective dosing method has also been verified in an actual sewer (Jiang et al, 2013a). Sulfide production was also reduced by more than 80% over a period of 10 days after FNA was once dosed at a pumping station for a period of 8 h. MA are more sensitive than SRB to FNA, and the laboratory dosing study demonstrated complete methane control, giving good evidence that FNA is effective for both methane mitigation and sulfide control in sewer systems.…”

Section: Fnamentioning

confidence: 69%

Measurement and understanding of methane emission from sewers

Liu¹

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Sewer emissions are a notorious problem that water utilities have to deal with. The production and emission of hydrogen sulfide is a well-known problem for decades, which is the primary cause of sewer odors and corrosion. However, hydrogen sulfide is not the only harmful emission from sewer networks. Methane can also be generated in sewers through methanogenesis. Methane is a highly potent greenhouse gas, which is significantly contributing to climate change. Over a 100-year horizon, 1 ton of CH 4 will induce a warming effect equivalent to 34 tons of CO 2 . It is also explosive with a lower explosive limit (LEL) of approximately 5% by volume, and thus poses a serious safety issue. Currently, very little attention has been paid to methane formation in sewer networks.Therefore, the overall aim of this thesis is to measure and understand methane emission from sewers.The limited studies conducted so far on methane measurement in both gas and liquid phases in sewers have relied on manual sampling followed by off-line laboratory-based chromatography analysis. These methods are labor-intensive when measuring methane emissions from a large number of sewers, and do not capture the dynamic variations in methane production.Therefore, the suitability of infrared (IR) spectroscopy-based online methane gas sensors for measuring methane in humid sewer air was investigated in both laboratory and field conditions. Under certain circumstances, humidity could become an issue, however, this can be solved by removing the humidity on the sensor probe surface. Also, IR sensors exhibit excellent linearity and can be applied with factory calibration. Furthermore, the detection limit of sensors is suitable for measuring methane gas in sewers. Field application of the sensors revealed that methane concentrations in sewer air are 3 -4 orders of magnitude higher than in the atmosphere, confirming that sewers are a source of methane. The continuous measurement also revealed that methane concentrations in sewer are highly dynamic.Complementary to the gas phase sensors, a new dissolved methane sensor was developed in this thesis. This device uses an online IR gas-phase methane sensor to measure methane under equilibrium conditions in a stripping chamber. The measured gaseous methane levels were then II converted to liquid-phase methane concentrations according to Henry's Law. The detection limit and range was noted to be suitable for sewer applications. Good linearity was also obtained during Contributions of sediments in gravity sewers to overall sewer emissions are poorly understood at present. Sediments collected from a gravity sewer were cultivated in a laboratory reactor fed with real wastewater for more than one year to obtain intact sediments for the study. Batch test results clearly showed significant sulfide and methane production from sewer sediments. Microsensor and pore water measurements of sulfide, sulfate and methane in the sediments, microbial community profiling along the depth of the sediments and mathematical modelli...

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“…Regarding the cleaning time for biofouling removal, Jiang et al have reported that 6-24 h exposure time would be sufficient for sewer biofilms inactivation at lab-scale [150]. Protocol optimisation should test if cleaning efficiency of FNA presented in this study could be achieved 70 less than 24 h.…”

Section: Protocol Optimisation For Ro Biofilm Cleaningmentioning

confidence: 92%

Biofouling control of reverse osmosis membranes using free nitrous acid

Filloux¹,

Wang²,

Pidou³

et al.

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Reverse osmosis (RO) membranes have been widely applied in membrane filtration processes for water purification, since the high selective RO membranes are designed to reject all materials with particle diameter larger than 10 angstrom (Å) [1]. However, this optimal selectivity leads to fouling that can greatly affect the performance and productivity of RO membranes. Biofouling remains as one of the major operational problems in RO processes and is caused by unwanted deposit and growth of microorganisms on the membrane. Numerous biofouling control strategies have been developed to restore the performance of RO membranes, but none of them are able to prevent or remove biofouling completely. A novel cleaning technique using a weak and monobasic acid (pKa=3.34, 25℃) named free nitrous acid (FNA) in combined with hydrogen dioxide (H 2 O 2 ) was proposed.The effects of FNA with or without H 2 O 2 on biofouling of RO membranes were investigated in Chapter 4, five RO membranes with different degree of biofouling were cleaned using FNA has achieved higher biomass removal than NaOH for both heavily fouled (86-96% versus 41-83%) and moderately fouled (92-95% against 89-92%) membranes, respectively.In accordance to the biomass removal, 6-32% of viable cells remained on the moderately fouled RO membranes under the impact of FNA cleaning (pH 3), whereas 38-58% of viable cells stayed on the heavily fouled RO membranes. These results revealed that FNA cleaning is more effective for moderately fouled membranes, implying that early cleaning for biofouling is preferable. Although applying FNA alone, or combining it with H2O2 have shown better efficiency at biofouling removal than NaOH, the cleaning efficiency has not been significantly improved (<1% of enhancement) by adding H 2 O 2 to FNA cleaning solutions. The effects of FNA on scaling of RO membranes were also studied using the same cleaning protocol developed for biofouling control. The results showed that FNA solutions at pH 2.0 and 3.0 were as efficient as conventional cleaning acids (hydrochloric acid and citric acid). The scaling layers which contain 32.4±1.7 g/cm 2 of calcium were completely removed by all acidic cleaning solutions. Based on the results, FNA is shown to be a promising ii cleaning agent for RO membrane biofouling and scaling removal.Further investigation focused on the effectiveness of FNA for biofouling prevention in RO processes (Chapter 5). The results showed that weekly FNA cleanings were unable to prevent fouling in the RO filtration systems, as the hydraulic performances (permeability and salt rejection) of RO membranes have gradually declined over two to three weeks filtration period.Although FNA cleaning was able to restore the permeability of RO membranes for one to two days, continuing declined permeability implied that the fouling rate was greater than the inhibition rate of FNA. The results of prevention tests also showed that FNA was more efficient at biomass inactivation and removal. The biomass contents and viable cells of the fouli...

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Dosing free nitrous acid for sulfide control in sewers: Results of field trials in Australia

Cited by 103 publications

References 27 publications

Producing free nitrous acid – A green and renewable biocidal agent – From anaerobic digester liquor

Producing free nitrous acid – A green and renewable biocidal agent – From anaerobic digester liquor

Measurement and understanding of methane emission from sewers

Biofouling control of reverse osmosis membranes using free nitrous acid

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