Decrease of Time for Pathogen Inactivation in Alkaline Disinfection Systems Using Pressure

Fitzmorris, Kari B.; Reimers, Robert S.; Oleszkiewicz, Jan A.; Little, Melvyn

doi:10.2175/106143006x111862

Cited by 6 publications

(5 citation statements)

References 5 publications

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“…Generally, addition of lime to faecal sludge releases ammonia which assists in the destruction of pathogens specifically coliforms [10,11] as cited by Spit et al [12]. The containment of ammonia in the reactor acts as a biocide that further kills pathogens [13]. Pathogen reduction for lime treatment is achieved by the high pH levels and the ammonia concentration induced through the addition of lime [14,15].…”

Section: Resultsmentioning

confidence: 99%

Off-Site Lime Stabilisation as an Option to Treat Pit Latrine Faecal Sludge for Emergency and Existing On-Site Sanitation Systems

Greya

Thole

Anderson³

et al. 2016

Journal of Waste Management

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Off-site lime stabilisation for treating faecal sludge was assessed by undertaking small-scale (35 L) and large-scale (600 L) field trials in Blantyre, Malawi. Hydrated lime was dosed to maintain pH 10, pH 10.5, pH 11, pH 11.5, and pH 12 depending on the buffer capacity of the faecal sludge in the four replica small-scale field trials. Significant reduction ofE. colito below the detection limit of 104 CFU/100 mL within 1 hour of treatment was reported for pH > 11. Based on the small-scale findings, large-scale field trials were conducted and greater than3 logremoval ofE. coliwas observed under pH 12 conditions. Therefore, based on the study, off-site lime stabilisation by dosing lime in the range of 10–35% w/w (dry solid basis), depending on the buffer capacity and solids content of the sludge to maintain pH > 11, can be used to sanitise faecal sludge during emergencies, as well as for existing on-site sanitation systems.

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Section: Resultsmentioning

confidence: 99%

Off-Site Lime Stabilisation as an Option to Treat Pit Latrine Faecal Sludge for Emergency and Existing On-Site Sanitation Systems

Greya

Thole

Anderson³

et al. 2016

Journal of Waste Management

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“…At pH levels greater than 12, the cell membranes of harmful pathogens are destroyed [ 18 ]. The high pH also leads to high fractions of non-ionised ammonium which, as detailed in the previous urea treatment section, will act as a biocide and contribute to pathogen removal if contained within the reactor [ 19 ].…”

Section: Introductionmentioning

confidence: 99%

Lactic Acid Fermentation, Urea and Lime Addition: Promising Faecal Sludge Sanitizing Methods for Emergency Sanitation

Anderson¹,

Malambo

Perez

et al. 2015

IJERPH

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In this research, three faecal sludge sanitizing methods—lactic acid fermentation, urea treatment and lime treatment—were studied for application in emergency situations. These methods were investigated by undertaking small scale field trials with pit latrine sludge in Blantyre, Malawi. Hydrated lime was able to reduce the E. coli count in the sludge to below the detectable limit within 1 h applying a pH > 11 (using a dosage from 7% to 17% w/w, depending faecal sludge alkalinity), urea treatment required about 4 days using 2.5% wet weight urea addition, and lactic acid fermentation needed approximately 1 week after being dosed with 10% wet weight molasses (2 g (glucose/fructose)/kg) and 10% wet weight pre-culture (99.8% pasteurised whole milk and 0.02% fermented milk drink containing Lactobacillus casei Shirota). Based on Malawian prices, the cost of sanitizing 1 m3 of faecal sludge was estimated to be €32 for lactic acid fermentation, €20 for urea treatment and €12 for hydrated lime treatment.

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“…Pilot testing was conducted at Tulane University in 2004 and indicated that the Bioset process met the criteria for a PEC process to disinfect to Class A (Fitzmorris et al 2007). This data is capsulated in Table 1.…”

Section: Resultsmentioning

confidence: 99%

Advances in Advanced Alkaline Stabilization and Disinfection

Brisolara¹,

Reimers²

2013

proc water environ fed

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The development of a new or innovative biosolids disinfection process not only has to function accordingly, but also must adhere to ever-increasing restrictions imposed by the federal government in addition to local and state governments. The purpose of this project was to conduct experiments to define an advanced alkaline process as PFRP by demonstrating the ability of the system to handle different sludge types and verifying the suggested optimum operating conditions indicated by previous tests. In order to achieve a Class A product, increased temperatures and/or ammonia addition is required to inactivate the highly resistant viruses, protozoan spores, and helminth eggs. The primary physical parameters of interest are pH, temperature and ammonia concentration with regard to disinfection. Studies at Tulane have observed disinfection under closed systems at 55 o C instead of 70 o C due to the containment of ammonia in a closed system (Reimers et al., 2004). In the disinfection of biosolids along with temperature caused by the exothermic reactions of quicklime and acid trimming, the non-charged disinfectants are a major player. For alkaline disinfection, ammonia is the primary constituent.The key parameters of interest to determine the efficacy of the process are the pathogens: Ascaris, fecal coliform and poliovirus. Aerobic endospores were also monitored as a potential indicator organism for alkaline processes. The data demonstrates the effectiveness of the closed alkaline system at inactivating helminth ova within 30 -40 minutes resulting in a greater than 2 log reduction. Most importantly, a greater than 3 log reduction was noted for all samples with regard to poliovirus and fecal coliform. The resistance of the aerobic endospores again proved to be higher than that of the other pathogens of concern. The data for the final runs conducted in the summer of 2010 substantiated the results of the previous studies conducted by Tulane. This data indicates meeting the criteria for Class A disinfected biosolids. The data related to pathogen testing, the required reductions, and indicator organism usage, will be presented along with the major hurdles to be overcome in pathogen recovery.

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Decrease of Time for Pathogen Inactivation in Alkaline Disinfection Systems Using Pressure

Cited by 6 publications

References 5 publications

Off-Site Lime Stabilisation as an Option to Treat Pit Latrine Faecal Sludge for Emergency and Existing On-Site Sanitation Systems

Off-Site Lime Stabilisation as an Option to Treat Pit Latrine Faecal Sludge for Emergency and Existing On-Site Sanitation Systems

Lactic Acid Fermentation, Urea and Lime Addition: Promising Faecal Sludge Sanitizing Methods for Emergency Sanitation

Advances in Advanced Alkaline Stabilization and Disinfection

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