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Impact of agricultural waste additive on 1-dimensional clay consolidation behaviour

  • Authors: Agbenyeku, Emem-Obong Emmanuel , Muzenda, Edison , Msibi, Innocent Mandla
  • Date: 2014
  • Subjects: Rice husk ash , Kaolinitic clay , Soil treatment , Soil consolidation , Soil stabilization , Agricultural waste , Landfills , Fills (Earthwork)
  • Type: Article
  • Identifier: http://ujcontent.uj.ac.za8080/10210/386034 , uj:5050 , http://hdl.handle.net/10210/13589
  • Description: Soil treatment is of vital concern in geoenvironmental and construction engineering in present times as suitable naturally occurring materials are rapidly depleted. Efforts are continually invested towards the resourceful utilization of wastes as fillers, cement enhancers, stabilizers and blenders with little or no significant impacts on the environment. This paper explains the use of a locally available and abundant agricultural waste- Rice husk ash (RHA) in West Africa, Nigeria for the treatment and stabilization of kaolinitic clay (KC) sampled from an active landfill site in Johannesburg, South Africa. The impact of incorporating different percentages of RHA on the compressibility characteristics of a parent compressible landfill KC sample was investigated under a One-dimensional consolidation test. Compacted soil specimens were treated at optimum water content (OWC) and maximum dry unit weight (MDUW) by the addition of agricultural waste material to the parent KC. The compacted specimens were subjected incremental vertical loading in a fixed ring consolidometer device. This was done with a view to closely simulate the waste loading effects from a typical landfill on a treated and parent clay/clayey bottom barrier based on one-dimensional consolidation behaviours. The introduction of RHA waste material to the parent KC revealed an outcome with substantial improvements in compaction characteristics. Hence, the results presented herein showed the agricultural waste to positively increase one-dimensional rigidity while settlement was effectively decreased. From results and analysis, the KC stabilized with RHA can withstand loadings from waste heaps under conditions as were applied in this study. With due recommended examination by geoenvironmental specialists, the stabilized material may be considered as an environmental and cost saving beneficiation approach for use in landfill liners.
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Industrial waste modified 1-dimensional compressibility of kaolinitic clay

  • Authors: Agbenyeku, Emmanuel Emem-Obong , Muzenda, Edison , Msibi, Innocent Mandla
  • Date: 2014
  • Subjects: Fly ash , Kaolinitic clay , Soil modification , Soil compressibility , Industrial wastes , Landfills , Fills (Earthwork)
  • Type: Article
  • Identifier: http://ujcontent.uj.ac.za8080/10210/365833 , uj:5053 , http://hdl.handle.net/10210/13592
  • Description: The modification of soil has become a major drive in construction and geoenvironmental engineering in recent years. Researches towards the effective incorporation of wastes as cement blenders and enhancers with environmental friendly impacts are increasing. This paper channeled the utilization of commercially available industrial waste- Fly ash (FA) in South Africa towards the modification and improvement of kaolinitic clay sampled from a disposal site. One-dimensional consolidation tests were conducted to investigate the effect of integrating varied proportions of FA on the compressibility behavioral patterns of a parent compressible landfill material. Compacted specimens were modified at optimum water content (OWC) and maximum dry unit weight (MDUW) by the incorporation of an industrial waste material to the parent soil. The generated specimens were subjected to incremental vertical loadings/pressures in a fixed ring odometer. This was done to simulate the impact of waste loads from a typical landfill on the consolidation characteristics of the modified specimens in a view for use as bottom liners in domestic waste containment facilities. The addition of different proportions of FA waste to the kaolinitic parent clay resulted in considerable improvements in compaction characteristics. Thus, the results of this study revealed that the incorporated industrial waste effectively increased one-dimensional stiffness and as such, successfully decreased settlement. Under adequate strength and operative conditions, the modified kaolinitic clay soil can withstand loadings from waste heaps and after recommended scrutiny by experts, may be initiated into landfill designs as an eco-friendly cost reducing agent.
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Potential efficiency and energy usage in a leachate treatment process

  • Authors: Agbenyeku, Emmanuel Emem-Obong , Muzenda, Edison , Msibi, Innocent Mandla
  • Date: 2016
  • Subjects: Landfills , Reverse osmosis , Leachate , Waste , Energy
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/93676 , uj:20377 , Citation: Agbenyeku, E.E., Muzenda, E. & Msibi, I.M. 2016. Potential efficiency and energy usage in a leachate treatment process.
  • Description: Abstract: Generated leachate in landfills is often as a result of the infiltration of rain, surface or running water into waste bodies. Numerous studies have revealed the potential impacts of leachate escape from landfill disposal facilities on human and environmental health. Although much is been done in most landfills in South Africa to ensure minimal leachate escape into immediate soil, surface and groundwater reserves, much more is still required. As such, the option of leachate treatment is gradually been explored. The potential efficiency and energy usage of a landfill waste water treatment plant (WWTP) for a simple leachate treatment process is explored. The WWTP process involves the basic treatment of the leachate with subsequent sequencing batch reactors (SBR), reverse osmosis unit (RO) and evaporation for additional concentration of RO yield. The process efficiency is appraised by conductivity, chemical oxygen demand (BOD), biochemical oxygen demand (BOD) and total nitrogen (TN) measurements. Energy usage is estimated by electrical input power, motor efficiency of power-consuming units and functional hours. 2.2% of the of the WWTP total operational real power consumption is gotten for the primary treatment process with 16.7% corresponding SBR operation and 13.2% RO unit. 2 unit evaporators consumes 61.5% and 0.78% for leachate recirculation to landfill from the total energy usage. Therefore, RO is taken as the most efficient leachate treatment process as it can dispense substantial amounts of water from the landfill leachate pond whereas, the evaporators are energy demanding.
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Potential risks of CCA-treated wood destined to landfills

  • Authors: Agbenyeku, Emmanuel Emem-Obong , Muzenda, Edison , Msibi, Innocent Mandla
  • Date: 2015
  • Subjects: Landfills , CCA-treated wood , Percolation
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/72876 , uj:18340 , Citation: Agbenyeku, E.E., Muzenda, E. & Msibi, I.M. 2015. Potential risks of CCA-treated wood destined to landfills.
  • Description: Abstract: In recent years, recycling has become the first best option of dealing with waste before landfilling is considered in cases of handling difficulties. In South Africa however, 41,000 tons of solid waste is destined for landfills daily; which includes huge chunks of waste from construction and demolition activities. The continued reliance of South Africa on the landfilling system could extend a while until economical recycling alternatives are introduced. Leachate generation and percolation is expected in these landfills on account of infiltration of water into the waste body from rain and/or runoffs. Although, it has been documented that arsenic, copper and chromium percolate soil systems, it however noted that occurring physical, chemical and biological activities may influence mobility of metals from generated leachate. This is particularly evident in cases where Chromated Copper Arsenate (CCA)-treated wood are disposed in monofills with consequential impacts on the environment. Laboratory investigation using a bespoke device to explore the environmental risk of depositing CCA-treated wood in monofills and/or open dumps was done; with a view to simulating worst case scenario of an unlined disposal facility that relied on the geology of the site. This scenario best indicates high concentrations and maximum formation of heavy metals. The bespoke device was assembled with chopped untreated wood and CCA-treated wood in a bottom chamber respectively, and de-ionized water was allowed to seep through from a reservoir forming leachate. The targeted chemical ions (arsenic, copper and chromium) from the leachate were analyzed by way of full spectral method on the effluent and were compared to South African standard of drinking water. The study therefore, revealed that CCA-treated wood formed hazardous concentration levels of chromium and arsenic which if not properly contained in real cases, could inflict severe contamination consequential to human and environmental health.
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The management of South African landfills and waste pickers on them : impacting lives and livelihoods

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