Dataset Information

Towards an off-grid fecal sludge treatment unit: demonstrating energy positive thermal treatment.

ABSTRACT: Background: There is an unmet demand for community-scale fecal sludge treatment units (FSTUs) that serve communities of between 1,000 and 50,000 people and are able to operate in non-sewered and off-grid environments. An emerging industry standard for FSTUs includes as a key criteria energy independence in steady-state. Theoretically, there is sufficient thermal energy available in fecal sludge to provide the electrical power needed to run the FSTU. However, such a system had never been implemented. Methods: Biomass Controls has previously demonstrated the thermal treatment of fecal sludge using the Biogenic Refinery, a thermal FSTU deployed in three sites in India. In this article we describe testing where a Biogenic Refinery was paired with a thermal fluid heat exchanger and organic Rankine cycle generator to generate electrical power. Results: This Biogenic Refinery combined heat and power system generated sufficient electrical power to offset electrical parasitic loads in steady-state operation and produce a surplus of 1.2 kWe. Conclusions: The results of the study demonstrate that there is an excess of energy available and reliable mechanisms to generate electrical energy using an FSTU. Additional steps are necessary to transition to a true off-grid FSTU.

SUBMITTER: Myers T

PROVIDER: S-EPMC6733003 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Towards an off-grid fecal sludge treatment unit: demonstrating energy positive thermal treatment.

Myers Taylor T Schoebitz Lars L Woolley Stuart S Sanchez Ferragut Jaime J Thostenson Jimmy J Jooss Kathy K Piascik Jeffery J Frechette August A Hotz Nico N Stoner Brian R BR Hallowell Jeffery J

Gates open research 20190410

<b>Background</b>: There is an unmet demand for community-scale fecal sludge treatment units (FSTUs) that serve communities of between 1,000 and 50,000 people and are able to operate in non-sewered and off-grid environments. An emerging industry standard for FSTUs includes as a key criteria energy independence in steady-state. Theoretically, there is sufficient thermal energy available in fecal sludge to provide the electrical power needed to run the FSTU. However, such a system had never been i ...[more]

PMID: 31508581

Similar Datasets

Project description:Omni Processors (OPs) are community-scale systems for non-sewered fecal sludge treatment. These systems have demonstrated their capacity to treat excreta from tens of thousands of people using thermal treatment processes (e.g., pyrolysis), but their relative sustainability is unclear. In this study, QSDsan (an open-source Python package) was used to characterize the financial viability and environmental implications of fecal sludge treatment via pyrolysis-based OP technology treating mixed and source-separated human excreta and to elucidate the key drivers of system sustainability. Overall, the daily per capita cost for the treatment of mixed excreta (pit latrines) via the OP was estimated to be 0.05 [0.03-0.08] USD·cap-1·d-1, while the treatment of source-separated excreta (from urine-diverting dry toilets) was estimated to have a per capita cost of 0.09 [0.08-0.14] USD·cap-1·d-1. Operation and maintenance of the OP is a critical driver of total per capita cost, whereas the contribution from capital cost of the OP is much lower because it is distributed over a relatively large number of users (i.e., 12,000 people) for the system lifetime (i.e., 20 yr). The total emissions from the source-separated scenario were estimated to be 11 [8.3-23] kg CO2 eq·cap-1·yr-1, compared to 49 [28-77] kg CO2 eq·cap-1·yr-1 for mixed excreta. Both scenarios fall below the estimates of greenhouse gas (GHG) emissions for anaerobic treatment of fecal sludge collected from pit latrines. Source-separation also creates opportunities for resource recovery to offset costs through nutrient recovery and carbon sequestration with biochar production. For example, when carbon is valued at 150 USD·Mg-1 of CO2, the per capita cost of sanitation can be further reduced by 44 and 40% for the source-separated and mixed excreta scenarios, respectively. Overall, our results demonstrate that pyrolysis-based OP technology can provide low-cost, low-GHG fecal sludge treatment while reducing global sanitation gaps.

Project description:The aim of this study is to use the life cycle assessment method to measure the environmental performance of the sludge incineration process in a wastewater treatment plant and to propose an alternative that can reduce the environmental impact. To show the damages caused by the treatment processes, the study aimed to use an endpoint approach in evaluating impacts on human health, ecosystem quality, and resources due to the processes. A case study was taken at Bissell Point Wastewater Treatment Plant in Saint Louis, Missouri, U.S. The plant-specific data along with literature data from technical publications were used to build an inventory, and then analyzed the environmental burdens from sludge handling unit in the year 2011. The impact assessment method chosen was ReCipe 2008. The existing scenario (dewatering-multiple hearth incineration-ash to landfill) was evaluated and three alternative scenarios (fluid bed incineration and anaerobic digestion with and without land application) with energy recovery from heat or biogas were proposed and analyzed to find the one with the least environmental impact. The existing scenario shows that the most significant impacts are related to depletion in resources and damage to human health. These impacts mainly came from the operation phase (electricity and fuel consumption and emissions related to combustion). Alternatives showed better performance than the existing scenario. Using ReCipe endpoint methodology, and among the three alternatives tested, the anaerobic digestion had the best overall environmental performance. It is recommended to convert to fluid bed incineration if the concerns were more about human health or to anaerobic digestion if the concerns were more about depletion in resources. The endpoint approach may simplify the outcomes of this study as follows: if the plant is converted to fluid bed incineration, it could prevent an average of 43.2 DALYs in human life, save 0.059 species in the area from extinction, and make a 62% reduction in the plant's current expenses needed by future generations to extract resources per year. At the same time it may prevent 36.1 DALYs in humans, save 0.157 species, and make a 101% reduction in current expenses on resources per year, if converting to anaerobic digestion.

Project description:A new sanitation technology has been proposed in which a laminated hydrophobic membrane contains and enhances drying of fecal sludge in a toilet, with particular focus on application to urban regions of low-income countries. The proposed technology uses a laminated hydrophobic membrane liner as an integral component of container-based sanitation systems. The focus of this study is to quantitatively evaluate the laminate's clogging after repeated use, which will affect replacement interval and might limit the laminate's application in container-based toilets. The membrane of the laminated hydrophobic membrane used in this process is hydrophobic and only allows vapor transport. Drying of water vapor using the laminated hydrophobic membrane occurs due to moderate temperature or humidity gradients, while other constituents such as aqueous dissolved solutes of fecal sludge are retained. Controlled laboratory experiments evaluated repeated use of a laminated hydrophobic membrane for fecal sludge drying, with mild brushing/rinsing of the laminate between each application. Drying occurred at a constant rate as long as the fecal sludge moisture content exceeded 11.6 (g/g), below which water activity <1. Over five drying cycles, at a significance level of ??=?0.05 the dimensionless drying rate in the constant-rate period was not reduced. While scanning electron microscopy and energy dispersive X-ray analyses of used laminated hydrophobic membrane showed deposition of fecal sludge on the inner fabric of the laminate, particulate accumulation was never sufficient to alter the fecal sludge drying rate. Experiments with only water indicated that the fecal sludge increased the effective diffusion length through the laminate by 10-30%. These data demonstrate that clogging of the laminated hydrophobic membrane is minor over five cycles of fecal sludge drying with mild rinsing between cycles, indicating that use of the laminate may be feasible in many field applications.

Dataset Information

Towards an off-grid fecal sludge treatment unit: demonstrating energy positive thermal treatment.

Publications

Towards an off-grid fecal sludge treatment unit: demonstrating energy positive thermal treatment.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets