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Article
Publication date: 1 May 2006

Saber A. El‐Shafai, Fayza A. Nasr, Fatma A. El‐Gohary, N. Peter van der Steen and Huub J. Gijzen

The main purpose of this study is to investigate the bioaccumulation pattern and fate of heavy metals in duckweed‐based wastewater treatment ponds with different depth.

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Abstract

Purpose

The main purpose of this study is to investigate the bioaccumulation pattern and fate of heavy metals in duckweed‐based wastewater treatment ponds with different depth.

Design/methodology/approach

Three replicates of four reactors were used in this experiment. The reactors were randomly distributed on the bench and filled with 50 percent diluted sewage for the control reactors whereas diluted sewage mixed with 5 mg Pb/l and 5 mg Zn/l was used for the treatment reactors. The reactors were stocked with Lemna gibba at 1,000 g fresh weight per each square meter. The culture tanks were exposed to temperature range of 21‐25°C and light regime of 16 hours light using halogen lamps and 8 hours dark. The light intensity was maintained around 200 μ E m−2 S−1. The experiment extended for 30 days. Regular monitoring of the growth performance of duckweed was carried out with subsequent analysis of dry matter, heavy metals, phosphorous and nitrogen content. Composite samples from the water phase were subjected to the analysis of ammonia, nitrite, nitrate, orthophosphate and sulfate concentration. The analysis of sediment and biofilm were carried out at the end of the experiment. Interpretation of results was carried out using one‐way analysis of variance.

Findings

Statistical analysis showed a significant reduction in the growth rate of duckweed within the first five days exposure time. After five days exposure, the growth rate in the treatments returned to the normal growth till day 15 after which the growth became significantly lower in the small and medium scale ponds. The results revealed that zinc is more bio‐available than lead and both metals are mostly precipitated in the sediment probably as sulfides.

Practical implications

The results help in enhancement of heavy metals removal in a small anaerobic pretreatment unit before entering to the pond system by sulfate addition.

Originality/value

The results of the study confirm the positive effect of pond depth in reducing the heavy metal toxicity to the duckweed‐based wastewater treatment ponds.

Details

Management of Environmental Quality: An International Journal, vol. 17 no. 3
Type: Research Article
ISSN: 1477-7835

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Article
Publication date: 1 October 2000

Fatma A. El‐Gohary, Fayza A. Nasr, Rifaat A. Wahaab and Hamdy I. Aly

Pre‐treatment of wastewater discharged from a potato‐chips factory was the subject of this study. Wastewater discharged from this factory is characterized by high values of BOD…

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Abstract

Pre‐treatment of wastewater discharged from a potato‐chips factory was the subject of this study. Wastewater discharged from this factory is characterized by high values of BOD, TSS and oil and grease (3,685, 4,115 and 169mg/l, respectively). Treatability studies via continuous aerobic and anaerobic methods treatment have been investigated. The results obtained showed marked improvement in the quality of the treated effluent using packing material versus the upflow anaerobic sludge bed reactor (UASB) without packing. An extra removal in COD (53 per cent), BOD (61 percent), TSS (52 per cent) and oil and grease (46 per cent) was obtained. Corresponding residual values were 398mgO2/l, 235mgO2/l, 108mg/l and 38mg/l, respectively. Based on the laboratory results, engineering designs and economic evaluation of the different treatment systems were developed.

Details

Environmental Management and Health, vol. 11 no. 4
Type: Research Article
ISSN: 0956-6163

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Article
Publication date: 8 December 2022

Timothy Adu Gyamfi, Clinton Ohis Aigbavboa and Wellington Didibhuku Thwala

Construction organisations cannot underestimate the improvement in public–private partnership (PPP) projects’ implementation. At the same time, construction organisations cannot…

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Abstract

Purpose

Construction organisations cannot underestimate the improvement in public–private partnership (PPP) projects’ implementation. At the same time, construction organisations cannot overlook the risk arising from engaging in PPP construction projects. Hence, this study aims to establish the influence of risk resource management (RRM) in managing PPP risk in the construction industry in Ghana.

Design/methodology/approach

The researchers adopted qualitative and quantitative research methods to achieve the aim of the study, in which Delphi questions and a close-ended questionnaire were developed. A total of 650 construction specialists, including procurement officers, consultants, project managers, quantity surveyors, site engineers and planning officers were chosen using random and purposive sampling techniques. Recovered data were analysed using descriptive statistics and confirmatory factor analysis (CFA). The CFA maximum likelihood estimation extractor compresses 19 variables into 3 pattern matrices.

Findings

The results of the study revealed three factors that measure RRM in Ghana’s PPP construction industry, including financial resource management which was influenced by communicating the budget to project team members and project partners understanding the budget, and material resource management which was influenced by the provision of materials transportation and provision of delivery programs and labour resource management which was impacted by a commitment to pay social security and taxes and provision of good salaries, to address RRM in PPP construction organisations.

Research limitations/implications

To incessantly improve the PPP risk management (RM) in construction through RRM, there should be a strong liaison between the universities, government agencies and the construction industry, and such collaboration will assist the industry to obtain first-hand information regarding the study findings and how they can be implemented to help the development of RM in the construction industry. This study is limited to Ghana and CFA and further study should explore structural equation model to determine the structure and measurement model of the risk resource variables.

Originality/value

The study may be valuable to industry stakeholders looking for new approaches to improve RM in their construction activities, particularly in PPP projects. Also, to assist reduce PPP risk, construction companies should use RRM in their organisations.

Details

Journal of Engineering, Design and Technology , vol. 22 no. 5
Type: Research Article
ISSN: 1726-0531

Keywords

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