Anaerobic digestion is the dominant pathway for pit latrine decomposition and is limited by intrinsic factors.

In vitro methods were used to assess the full potential for decomposition (measured as biogas formation) from pit latrine samples taken from the top layer of 15 Tanzanian latrines. We found considerable variability in the decomposition rate and extent. This was compared with decomposition in the same latrines, measured by comparing top layer composition with fresh stools and deeper (older) layers, to assess whether this potential was realised in situ. Results showed a close match between the extent of organic material breakdown in situ and in vitro, indicating that anaerobic digestion is the dominant pathway in latrines. The average potential decrease in chemical oxygen demand (COD) (determined as methane production in vitro within 60 days) and actual measured decrease in situ are 68.9% ± 11.3 and 69.7% ± 19.4, respectively. However in the in vitro tests, where samples were diluted in water, full decomposition was achieved in 2 months, whereas in situ it can take years; this suggests that water addition may offer a simple route to improving latrine performance. The results also allowed us to estimate, for the first time to our knowledge using experimental data, the contribution that latrines make to greenhouse gas emissions globally. This amounts to ∼2% of annual US emissions

Analysis of pit latrine microbiota reveals depth-related variation in composition, and key parameters and taxa associated with latrine fill-up rate

Funding statement This research received financial support from the Bill and Melinda Gates Foundation (grant number OPP52641 to the London School of Hygiene and Tropical Medicine). AWW and JP were supported by the Wellcome Trust [grant number 098051]. AWW and the Rowett Institute, University of Aberdeen, receive core funding support from the Scottish Government Rural and Environmental Science and In review Analysis Service (RESAS). UZI is funded by NERC Independent Research Fellowship (NE/L011956/1) and further supported by EPSRC (EP/P029329/1 and EP/V030515/1). CQ is funded through an MRC fellowship (MR/M50161X/1) as part of the MRC Cloud Infrastructure for Microbial Bioinformatics consortium (MR/L015080/1). Acknowledgements In review Pit latrine microbiota associated with depth and fill-up rate. We would like to thank all the field and laboratory teams and to all the pit latrine owners who participated in this study. We also thank Paul Scott, Richard Rance and members of the Wellcome Sanger Institute's sequencing team for generating 16S rRNA gene data.Peer reviewedPublisher PD

Towards a standardization of biomethane potential tests

Production of biogas from different organic materials is a most interesting source of renewable energy. The biomethane potential (BMP) of these materials has to be determined to get insight in design parameters for anaerobic digesters. Although several norms and guidelines for BMP tests exist, inter-laboratory tests regularly show high variability of BMPs for the same substrate. A workshop was held in June 2015, in Leysin, Switzerland, with over 40 attendees from 30 laboratories around the world, to agree on common solutions to the conundrum of inconsistent BMP test results. This paper presents the consensus of the intense roundtable discussions and cross-comparison of methodologies used in respective laboratories. Compulsory elements for the validation of BMP results were defined. They include the minimal number of replicates, the request to carry out blank and positive control assays, a criterion for the test duration, details on BMP calculation, and last but not least criteria for rejection of the BMP tests. Finally, recommendations on items that strongly influence the outcome of BMP tests such as inoculum characteristics, substrate preparation, test setup, and data analysis are presented to increase the probability of obtaining validated and reproducible results.info:eu-repo/semantics/publishedVersio

A review of nature-based solutions for resource recovery in cities

Our modern cities are resource sinks designed on the current linear economic model which recovers very little of the original input. As the current model is not sustainable, a viable solution is to recover and reuse parts of the input. In this context, resource recovery using nature-based solutions (NBS) is gaining popularity worldwide. In this specific review, we focus on NBS as technologies that bring nature into cities and those that are derived from nature, using (micro)organisms as principal agents, provided they enable resource recovery. The findings presented in this work are based on an extensive literature review, as well as on original results of recent innovation projects across Europe. The case studies were collected by participants of the COST Action Circular City, which includes a portfolio of more than 92 projects. The present review article focuses on urban wastewater, industrial wastewater, municipal solid waste and gaseous effluents, the recoverable products (e.g., nutrients, nanoparticles, energy), as well as the implications of source-separation and circularity by design. The analysis also includes assessment of the maturity of different technologies (technology readiness level) and the barriers that need to be overcome to accelerate the transition to resilient, self-sustainable cities of the future

Isolation and characterization of a new CO-utilizing strain, Thermoanaerobacter thermohydrosulfuricus subsp. carboxydovorans, isolated from a geothermal spring in Turkey

A novel anaerobic, thermophilic, Gram-positive, spore-forming, and sugar-fermenting bacterium (strain TLO) was isolated from a geothermal spring in Ayaş, Turkey. The cells were straight to curved rods, 0.4–0.6 μm in diameter and 3.5–10 μm in length. Spores were terminal and round. The temperature range for growth was 40–80°C, with an optimum at 70°C. The pH optimum was between 6.3 and 6.8. Strain TLO has the capability to ferment a wide variety of mono-, di-, and polysaccharides and proteinaceous substrates, producing mainly lactate, next to acetate, ethanol, alanine, H2, and CO2. Remarkably, the bacterium was able to grow in an atmosphere of up to 25% of CO as sole electron donor. CO oxidation was coupled to H2 and CO2 formation. The G + C content of the genomic DNA was 35.1 mol%. Based on 16S rRNA gene sequence analysis and the DNA–DNA hybridization data, this bacterium is most closely related to Thermoanaerobacter thermohydrosulfuricus and Thermoanaerobacter siderophilus (99% similarity for both). However, strain TLO differs from Thermoanaerobacter thermohydrosulfuricus in important aspects, such as CO-utilization and lipid composition. These differences led us to propose that strain TLO represents a subspecies of Thermoanaerobacter thermohydrosulfuricus, and we therefore name it Thermoanaerobacter thermohydrosulfuricus subsp. carboxydovorans

Biomethane from industrial and municipal wastewater

Remains of drainage systems to remove waste and latrines have been found in houses from the Mesopotamian Empire (3500-2500 BC); ancient Rome had its Cloaca Maxima, and there still exists a working 4000-year-old sewer system in Greece. Nevertheless, it was not until the late nineteenth century, and after a fourteenth-century long dark age, that it was recognized that municipal waste water needs to be removed from its origin and treated to prevent the outbreak of diseases (Lofrano and Brown 2010). Until then, wastewater had been discharged in surface water or so-called “night soil” (toilet waste) and collected and used for fertilization. Later, in the early twentieth century, biological oxygen demand (BOD) was introduced as a measure of pollution and the first wastewater treatment systems were installed. Recently, the recovery of nutrients, reuse of water, production of intermediates, and generation of energy have become important incentives for the treatment of wastewater from both industrial and municipal origins. This may be more feasible through separation at the source and improved design of water usage and treatment systems (Guest et al. 2009; Larsen et al. 2009). Aerobic treatment was and still is the main technology used for the treatment of municipal wastewater in the north and cold climate areas. In the twentieth century, the possible application of anaerobic systems for the treatment of industrial wastewater and municipal wastewater in warmer climates was recognized after the development of the upflow anaerobic sludge bed (UASB) system in Wageningen in the 1970s (Lettinga 2014; van Lier et al. 2015). Nowadays, with new treatment designs and the paradigm shift toward seeing wastewater as a source of valuable resources, the application of anaerobic technology may be expanded toward treating municipal sewage in cold climates as well. Anaerobic treatment has its advantages, for example, lower excess sludge production, high applicable loadings, and lower energy demands, combined with biogas production. Initially, those were the reasons for the application of anaerobic treatment. Nowadays, the fact that nutrients (N and P) are not destroyed (e.g., emitted as N2) but released as recoverable ions is considered an additional advantage, since this facilitates recovery. Therefore, anaerobic technology has a central role in existing and newly developed waste treatment systems (Figure 3.1). It is, however, important to consider that in most cases, posttreatment of anaerobic effluent is warranted to guarantee that limits for safe discharge of the effluent are met (von Sperling and de Lemos Chrenicharo 2002).</p

Biomethane from industrial and municipal wastewater

<p>Remains of drainage systems to remove waste and latrines have been found in houses from the Mesopotamian Empire (3500-2500 BC); ancient Rome had its Cloaca Maxima, and there still exists a working 4000-year-old sewer system in Greece. Nevertheless, it was not until the late nineteenth century, and after a fourteenth-century long dark age, that it was recognized that municipal waste water needs to be removed from its origin and treated to prevent the outbreak of diseases (Lofrano and Brown 2010). Until then, wastewater had been discharged in surface water or so-called “night soil” (toilet waste) and collected and used for fertilization. Later, in the early twentieth century, biological oxygen demand (BOD) was introduced as a measure of pollution and the first wastewater treatment systems were installed. Recently, the recovery of nutrients, reuse of water, production of intermediates, and generation of energy have become important incentives for the treatment of wastewater from both industrial and municipal origins. This may be more feasible through separation at the source and improved design of water usage and treatment systems (Guest et al. 2009; Larsen et al. 2009). Aerobic treatment was and still is the main technology used for the treatment of municipal wastewater in the north and cold climate areas. In the twentieth century, the possible application of anaerobic systems for the treatment of industrial wastewater and municipal wastewater in warmer climates was recognized after the development of the upflow anaerobic sludge bed (UASB) system in Wageningen in the 1970s (Lettinga 2014; van Lier et al. 2015). Nowadays, with new treatment designs and the paradigm shift toward seeing wastewater as a source of valuable resources, the application of anaerobic technology may be expanded toward treating municipal sewage in cold climates as well. Anaerobic treatment has its advantages, for example, lower excess sludge production, high applicable loadings, and lower energy demands, combined with biogas production. Initially, those were the reasons for the application of anaerobic treatment. Nowadays, the fact that nutrients (N and P) are not destroyed (e.g., emitted as N2) but released as recoverable ions is considered an additional advantage, since this facilitates recovery. Therefore, anaerobic technology has a central role in existing and newly developed waste treatment systems (Figure 3.1). It is, however, important to consider that in most cases, posttreatment of anaerobic effluent is warranted to guarantee that limits for safe discharge of the effluent are met (von Sperling and de Lemos Chrenicharo 2002).</p

Biomethane from industrial and municipal wastewater

<p>Remains of drainage systems to remove waste and latrines have been found in houses from the Mesopotamian Empire (3500-2500 BC); ancient Rome had its Cloaca Maxima, and there still exists a working 4000-year-old sewer system in Greece. Nevertheless, it was not until the late nineteenth century, and after a fourteenth-century long dark age, that it was recognized that municipal waste water needs to be removed from its origin and treated to prevent the outbreak of diseases (Lofrano and Brown 2010). Until then, wastewater had been discharged in surface water or so-called “night soil” (toilet waste) and collected and used for fertilization. Later, in the early twentieth century, biological oxygen demand (BOD) was introduced as a measure of pollution and the first wastewater treatment systems were installed. Recently, the recovery of nutrients, reuse of water, production of intermediates, and generation of energy have become important incentives for the treatment of wastewater from both industrial and municipal origins. This may be more feasible through separation at the source and improved design of water usage and treatment systems (Guest et al. 2009; Larsen et al. 2009). Aerobic treatment was and still is the main technology used for the treatment of municipal wastewater in the north and cold climate areas. In the twentieth century, the possible application of anaerobic systems for the treatment of industrial wastewater and municipal wastewater in warmer climates was recognized after the development of the upflow anaerobic sludge bed (UASB) system in Wageningen in the 1970s (Lettinga 2014; van Lier et al. 2015). Nowadays, with new treatment designs and the paradigm shift toward seeing wastewater as a source of valuable resources, the application of anaerobic technology may be expanded toward treating municipal sewage in cold climates as well. Anaerobic treatment has its advantages, for example, lower excess sludge production, high applicable loadings, and lower energy demands, combined with biogas production. Initially, those were the reasons for the application of anaerobic treatment. Nowadays, the fact that nutrients (N and P) are not destroyed (e.g., emitted as N2) but released as recoverable ions is considered an additional advantage, since this facilitates recovery. Therefore, anaerobic technology has a central role in existing and newly developed waste treatment systems (Figure 3.1). It is, however, important to consider that in most cases, posttreatment of anaerobic effluent is warranted to guarantee that limits for safe discharge of the effluent are met (von Sperling and de Lemos Chrenicharo 2002).</p

Biomethane from industrial and municipal wastewater

Remains of drainage systems to remove waste and latrines have been found in houses from the Mesopotamian Empire (3500-2500 BC); ancient Rome had its Cloaca Maxima, and there still exists a working 4000-year-old sewer system in Greece. Nevertheless, it was not until the late nineteenth century, and after a fourteenth-century long dark age, that it was recognized that municipal waste water needs to be removed from its origin and treated to prevent the outbreak of diseases (Lofrano and Brown 2010). Until then, wastewater had been discharged in surface water or so-called “night soil” (toilet waste) and collected and used for fertilization. Later, in the early twentieth century, biological oxygen demand (BOD) was introduced as a measure of pollution and the first wastewater treatment systems were installed. Recently, the recovery of nutrients, reuse of water, production of intermediates, and generation of energy have become important incentives for the treatment of wastewater from both industrial and municipal origins. This may be more feasible through separation at the source and improved design of water usage and treatment systems (Guest et al. 2009; Larsen et al. 2009). Aerobic treatment was and still is the main technology used for the treatment of municipal wastewater in the north and cold climate areas. In the twentieth century, the possible application of anaerobic systems for the treatment of industrial wastewater and municipal wastewater in warmer climates was recognized after the development of the upflow anaerobic sludge bed (UASB) system in Wageningen in the 1970s (Lettinga 2014; van Lier et al. 2015). Nowadays, with new treatment designs and the paradigm shift toward seeing wastewater as a source of valuable resources, the application of anaerobic technology may be expanded toward treating municipal sewage in cold climates as well. Anaerobic treatment has its advantages, for example, lower excess sludge production, high applicable loadings, and lower energy demands, combined with biogas production. Initially, those were the reasons for the application of anaerobic treatment. Nowadays, the fact that nutrients (N and P) are not destroyed (e.g., emitted as N2) but released as recoverable ions is considered an additional advantage, since this facilitates recovery. Therefore, anaerobic technology has a central role in existing and newly developed waste treatment systems (Figure 3.1). It is, however, important to consider that in most cases, posttreatment of anaerobic effluent is warranted to guarantee that limits for safe discharge of the effluent are met (von Sperling and de Lemos Chrenicharo 2002).</p