Journal of Humanitarian Engineering

VOL 9 FRONT MATTER

Fiona Johnson — Thu, 22 Feb 2024 22:22:56 +0000

Guest Editorial

Aaron Opdyke — Thu, 22 Feb 2024 22:10:25 +0000

Editorial

Coconut husks as a packing media in anaerobic filters for the treatment of septic tank effluent in Tonga

Nicola Brown, Zoe Daborn, John Edwards, Shazwani Shamsulgafar — Wed, 21 Feb 2024 00:00:00 +0000

Septic tanks can become overloaded overtime due to increases in the size of households or the build-up of sludge. This results in the wastewater spending less time within the tank and therefore a reduced level of treatment. One solution to enhance treatment is to add an anerobic filter after the existing septic tank. The anaerobic filter requires media for the establishment of a biofilm and the use of coconut husks were identified as a possibility due to their abundance. Both green and brown coconut husks were imported from Tonga and tested in laboratory scale anerobic filters treating synthetic wastewater. The treatment performance was monitored in terms of the chemical oxygen demand (COD) which is a measure of organic strength. There was also potential for organic material to leach out of the coconut husks so additional testing was done to evaluate this. It was found that four times more COD was leached from the green coconut husks showing that brown coconut husks were the better choice. The brown coconut husk reactor reduced the COD concentration by 49%. This study has indicated that there is value in examining the feasibility of implementing an anaerobic filter using brown coconut husks to enhance wastewater treatment from septic tanks. Further research should focus on examining whether any nutrients are released from the husk and then practical considerations such as the scale needed for a household and maintenance requirements.

Determining Hydraulic Ram Pump Feasibility

Maxwell Pawlick, David Vaughn, Jeffery Plumblee — Wed, 21 Feb 2024 00:00:00 +0000

Hydraulic ram pumps have been used for over 200 years to pump water using only the potential energy of elevated water. Today, the low price and simplicity of the materials and methods required to construct ram pumps make them an excellent option for small and mid-sized water systems in developing countries where elevated water is available. However, ram pumps are risky to implement because they will fail to deliver water if they are not designed correctly. Evaluating pump designs requires complex computer modeling typically unavailable in developing countries. Existing design documents for users without a specialization in fluid mechanics use vague rules of thumb to simplify the design process. Unfortunately, these rules cannot reliably predict whether or not a ram pump will deliver water in many cases. Recent research has focused on developing pump efficiency equations from non-dimensional analyses of experimental data, developing guidelines to optimize designs, and modeling ram pump function with numerical methods. Currently, the literature has not provided the typical designer with accurate and accessible methods for predicting the maximum delivery head or the delivery flowrate of a specific design. This study models the acceleration of fluid in the drive pipe and the intensity of the pressure spike to determine the feasibility of a wide variety of ram pump designs with a higher degree of certainty than previous rules of thumb. The model can be used in a Matlab program that determines if a design will function based on design parameters input by the user. The Matlab method was used along with conservative assumptions to predict the minimum design characteristics required for several common scenarios for easy reference. This work will allow a wider proliferation of hydraulic ram pumps through more accurate design tools, and reduce the cost of water systems for small developing communities.

Is there a case for gridshell structures in humanitarian assistance and disaster relief efforts?

Thomas Imhoff, Samar R. Malek — Thu, 22 Feb 2024 22:22:14 +0000

This article focuses on the core concerns of shelter and settlement, and more specifically focuses on large-span shelters in humanitarian assistance and disaster relief (HA/DR) efforts. Furthermore, this article introduces the audience to novel large-span structures called gridshells. This paper presents a parametric, computational study that quantifies the efficacy of bracing orientation and arrangement on the load carrying capacity of gridshells. The varied parameters include the grid density (“16 by 16” to “30 by 30”) and the bracing scheme (unbraced, continuous fully-braced, discontinuous fully-braced, continuous half-braced, and discontinuous half-braced). Four load cases were analyzed, namely a symmetric distributed load, an asymmetric distributed load, a centered point load, and an off-centered point load. The results of the study provide designers with trends and basic design options upon which they can base further analysis depending on the requirements of the final structure.

VOL 9 BACK MATTER

Fiona Johnson — Thu, 22 Feb 2024 22:11:38 +0000