Dr Martin Pritchard

There has been very little scientific research work into the use of plant extracts to purify groundwater. Research studies on the purification of groundwater have mainly been carried out in developed countries and have focused on water purification systems using aluminium sulphate (a coagulant) and chlorine (a disinfectant). Such systems are expensive and not viable for rural communities due to abject poverty. Shallow well water, which is commonly available throughout Africa, is often grossly contaminated and usually consumed untreated. As a result, water-related diseases kill more than 5 million people every year worldwide. This research was aimed at examining natural plant extracts in order to develop inexpensive ways for rural communities to purify their groundwater. The study involved creating an inventory of plant extracts that have been used for water and wastewater purification. A prioritisation system was derived to select the most suitable extracts, which took into account criteria such as availability, purification potential, yield and cost of extraction. Laboratory trials were undertaken on the most promising plant extracts, namely: Moringa oleifera, Jatropha curcas and Guar gum. The extracts were added to water samples obtained from five shallow wells in Malawi. The trials consisted of jar tests to assess the coagulation potential and the resulting effect on physico-chemical and microbiological parameters such as temperature, pH, turbidity and coliforms. The results showed that the addition of M. oleifera, J. curcas and Guar gum can considerably improve the quality of shallow well water. Turbidity reduction was higher for more turbid water. A reduction efficiency exceeding 90% was achieved by all three extracts on shallow well water that had a turbidity of 49 NTU. A reduction in coliforms was about 80% for all extracts. The pH of the water samples increased with dosage, but remained within acceptable levels for drinking water for all the extracts. Overall, M. oleifera powder produced superior results, followed by Guar gum and lastly J. curcas. There is a need to carry out further more detailed tests, which include toxicity to guarantee the safety of using plant extracts as a coagulant in the purification of drinking water for human consumption.

Lack of safe drinking water is a major problem in developing countries. Within Africa most people rely mainly on local groundwater sources for their water needs. These can be deep boreholes or shallow wells, the latter are normally found in poorer communities as they are the least expensive to construct. Over time water from these sources can be contaminated leading to fatal consequences. Previous monitoring of the quality of water from boreholes and shallow wells have been irregular, with the focus being mainly on boreholes. Information on seasonal water quality changes in shallow wells used by rural communities in Malawi has generally been lacking. A study was conducted from 2006 to 2007 to determine the quality of water from shallow wells in three districts in southern Malawi namely, Balaka, Chikwawa and Zomba districts. Water samples from 21 covered and five open shallow wells were analysed for chemical, microbiological and physical parameters using a portable water testing kit. Sampling was carried out at four different times of the year i.e. in August and October 2006 (dry season) and February and April 2007 (wet season). Microbiological data indicated that around 80% of the samples, obtained from the covered wells, failed to meet safe drinking water limits, set by World Health Organisation guidelines and Malawi Bureau of Standards, of zero total and faecal colony forming units (cfu)/100 ml. Values in excess of 1000 cfu/100 ml were noted in 10% of the samples, indicating gross contamination and the probability of pathogens being present. Contamination levels were higher during the wet season than the dry season in all three districts. Arsenic, ammonia, nitrate, nitrite and sulphate were all within the acceptable limits. Elevated levels of hardness, turbidity were noted in certain wells.

The provision of safe drinking water is a fundamental right of basic health and an extremely high priority of the Malawi Poverty Reduction Strategy. Only 40% of the people in Malawi have access to safe drinking water at any one time. Conventional water purification systems are prohibitively expensive for developing countries. The bulk of research work carried out in developing countries has concentrated on surface and borehole water quality with barely any work on monitoring water quality from shallow wells. The extent of pollution in shallow wells together with innovative, sustainable and economical solutions for rural villagers needs to be developed. This research work has focused on establishing data on water quality from shallow wells in southern Malawi with the view to developing a technology that uses indigenous plant extracts to purify the groundwater. An in-situ water testing kit was used to determine the water quality. The majority of the physico-chemical parameters were found to be within the recommended limits; however, microbiological water quality results showed that the water can be grossly polluted with faecal matter and the likely presence of disease causing microorganisms. Preliminary laboratory tests on a powdered extract from the common indigenous plant Moringa oleifera are sufficiently encouraging for microbiological purification for further more detailed work to be planned. © 2009 Springer Netherlands.

It is now very difficult to find a construction site that does not utilise any geosynthetic products. Materials used in the manufacture of geosynthetics are primarily synthetic polymers – generally derived from the by-products of the oil industry. As a result of the finite nature of these raw materials and their associated pollution streams, there is growing pressure to use renewable resources for sustainable production. Also, the majority of geosynthetic applications are only required to perform for a short period of time, thereby leaving an alien residual in the ground for many years to come. Natural (vegetable) fibres provide a more sustainable alternative to polymeric based materials, particularly for short-term applications – termed limited-life geotextiles (LLGs). This paper presents an overview of an extensive study that has been undertaken on the development of reinforcing LLGs manufactured from renewable and biodegradable vegetable fibres for short-term applications. Initially, structural form is considered. It is shown that LLGs can have tensile strength of up to 100 kN.m-1, which is directly comparable to a mid-range geosynthetic product. The shear interaction properties of the LLGs was then compared to a number of different commercially available geotextile structures – manufactured from both natural and synthetic materials. The results demonstrate that coefficient of interaction values of around unity can be achieved with these LLGs. This is about 20–25% more shear resistance than their synthetic equivalent. The difference stemming primarily from the coarseness of the vegetable fibres themselves but also from the novel structural form. In terms of longevity, durability tests have been undertaken on the LLGs in various ground conditions. The data obtained indicate that degradation rates are sensitive to fibre type, together with the amount of water present in the soil. Coir fibre performed the best in worst deterioration environment tested. A simple basal embankment analysis is then presented to demonstrate a potential end application for the short-term reinforcing LLGs. In this analysis, it is shown that the rate at which the underlying embankment soil gains in effective stress, due to the dissipation of excess pore water pressure, could be designed to correspond to the decline in tensile strength from the degrading LLG.

The provision of safe drinking water is a fundamental right of basic health and an extremely high priority of the Malawi Poverty Reduction Strategy. Only 40% of the people in Malawi have access to safe drinking water at any one time. Conventional water purification systems are prohibitively expensive for developing countries. The bulk of research work carried out in developing countries has concentrated on surface and borehole water quality with barely any work on monitoring water quality from shallow wells. The extent of pollution in shallow wells together with innovative, sustainable and economical solutions for rural villagers needs to be developed. This research work has focused on establishing data on water quality from shallow wells in southern Malawi with the view to developing a technology that uses indigenous plant extracts to purify the groundwater. An in-situ water testing kit was used to determine the water quality. The majority of the physico-chemical parameters were found to be within the recommended limits; however, microbiological water quality results showed that the water can be grossly polluted with faecal matter and the likely presence of disease causing microorganisms. Preliminary laboratory tests on a powdered extract from the common indigenous plant Moringa oleifera are sufficiently encouraging for microbiological purification for further more detailed work to be planned. © Springer Science + Business Media B.V. 2009.

The industrial heritage of the UK has given rise to around 100,000 sites, being classified as contaminated. There are many different techniques that have recently been developed to remediate land. Thermal desorption is one of these techniques. Contaminants in the soil are volatilised, which are then removed by a thermal or catalytic oxidiser. The chemical and physical properties of the ‘burnt’ soil’, termed thermally desorbed soil (TDS), have significantly changed but is typically still disposed of to landfill. The use of supplementary cementing materials has become a central aspect of construction economics and environmental preservation. This study therefore investigated the potential use of TDS as a partial cement replacement material. Cement was replaced from 0% (as the control) to 30% TDS in 10% increments. The compressive strength of the mortar cubes was then determined at intervals of 7, 28 and 91 days. For a direct comparison, a well-established pozzolanic material, fly ash (FA) was tested throughout the programme. Strength was indirectly related to replacement level, with the control initially (up to 7 days) gaining, and thereafter retaining, the highest degree of strength. However, after 7 days the rate of gain in strength was higher for the replacement mixes (FA and TDS) than the control. There was no significant strength difference between the FA and TDS mixes up to 20% replacement. Hence, based on these initial strength results, the performance of TDS as a partial cement replacement (up to 20%) was directly equivalent to that of FA. Environmental benefits for the use of TDS as a partial cement replacement would be twofold; firstly, by using a waste material rather than disposing to landfill; and secondly by using less cement. This would result in less carbon dioxide (CO2) being released into the atmosphere during the cement manufacturing process, which is currently responsible for 7–10% of the global CO2 emissions.

The industrial heritage of the UK has given rise to around 100,000 sites, beingclassified as contaminated. In particular the former Avenue Coking Works, Chesterfield,UK in the 1990s was classified as one of the most contaminated sites in Western Europe.The site was left derelict after its working life and was never decommissioned. Chemicaltanks, pipe work, sumps, gantries and contaminated lagoons were never drained down;the condition of these deteriorated. This coupled with site operation has caused severeground pollution. Major contaminants identified included PAHs, phenols, mineral oil,BTEX, cyanides, tyres, metal, asbestos and spent oxide. In 2001 a series of remediationtechniques were trialled to determine the superlative form of remediation. These trialsincluded bioremediation, thermal desorption, soil washing, cement stabilisation and coincineration.The enhanced thermal conduction (ETC) was the thermal desorptiontechnology used which was found to be the most effective technology for treating thistype of soil. Contamination levels such as PAHs (total 16 USEPA) were significantreduced from 76,000 mg/kg to 500 mg/kg at a cost of £60 per cubic metre.In addition to the reduction in contamination levels the ETC process alsosignificantly improved the geotechnical properties/parameters of the soil. The CBR valueincreased from 11% to 107%; this was related to the high uniformity coefficient of thesoil where excellent particle interlock would have been obtained. Humus would have alsobeen destroyed by the thermal process, which in turn would relate to a greater interlockbetween soil particles. The thermal process also enhanced the shearing resistance by afactor of two from 17° to 34°. Thus, the residual soil has the potential to be reused as a fillmaterial (Grade 1A) under the Specification for Highway Works, UK (2007). Theapplication for its reuse has been demonstrated in the chapter for an engineeredembankment. © 2010 Nova Science Publishers, Inc. All rights reserved.

Soil is one of the most important materials in construction, however it is often neglected in other construction material textbooks. It is one of the most variable materials to consider as it is naturally occurring. Also, it will be, almost certainly, inconsistent from one site to the next site. The most important elements to consider are: the range of soils, their properties/parameters and what causes variations in these values.

About 80% of all illnesses and over one-third of deaths in developing countries are related to poor water quality and sanitation facilities. The majority of research work undertaken on water in developing countries has focussed on surface and borehole water with hardly any work being undertaken on shallow well water. A study was conducted between 2005 and 2007 to determine water quality from shallow wells in southern Malawi. Over 2,700 samples were analysed for microbiological, chemical and physical contamination, namely: total coliforms (TC), faecal coliforms (FC), turbidity, total dissolved solids, electrical conductivity, pH, hardness, ammonia, arsenic, nitrate, nitrite and sulphate. Sampling was undertaken during both the wet and dry season to find the change in water quality with season. The results indicated that shallow wells tested were heavily polluted with both TC and FC. The pollution levels were higher in the wet season than the dry season. About 94% of all the wells tested failed to meet the Ministry of Water Development (MoWD) TC guideline value of 50 cfu/100 ml for untreated drinking water in the wet season, while about 80% of the wells failed in the dry season. Approximately 83% of all the wells tested failed to meet the MoWD FC guideline value of 50 cfu/100 ml in the wet season, while about 50% of the wells failed in the dry season. The difference in season was significant for both total and faecal coliforms (p<0.05). The majority of the physico-chemical parameters were found to be within the recommended limits. Parameters that were found to be slightly out of the range were pH, turbidity total dissolved solids and electrical conductivity in a small number of wells. © 2010 by Nova Science Publishers, Inc. All rights reserved.

Microbially induced calcite precipitation (MICP) is an emerging solution to issues faced by geotechnical engineers that has yet to turn its attention to strengthening fine particle clays, including lateritic soil. The lateritic clays found in tropical regions have long been used as a low cost construction material for earth roads linking rural village clusters. However, earth roads are exposed to prolonged tropical wet seasons and become inundated with rainwater, deteriorating their ability to bear traffic. MICP soil strengthening may provide a low cost, sustainable solution that would allow earth roads to remain usable. This paper presents the first phase of geotechnical strength related tests undertaken on a lateritic soil, prior to any MICP treatment, including plasticity index, Proctor compaction, Californian bearing ratio (CBR) and unconfined compressive strength (UCS). They have been undertaken to provide the baseline data against which future MICP treated samples can be assessed. The results indicate that the lateritic sample was a low plasticity clay, which may be prone to turbulent shearing when past its semisolid/plastic limit of 12 %. When tested at 12.5 % moisture content, the values of CBR and UCS fell by 96.4 and 87.4 %, respectively, when compared to samples tested at 7.5 % moisture content.

Lateritic soils are frequently utilised in tropical areas of the developing world as an engineering material in the construction of rural earth roads, usually in the form of engineered natural surface (ENS) roads. The heavy, seasonal rainfalls common to the tropics results in ENS roads becoming quickly saturated with rainwater, and no longer accessible to motorised transportation. Microbially induced calcite precipitation (MICP) has been successfully used as a treatment process to decrease the permeability of clean, cohesionless sands by studies trying to impede the movement of groundwater, and any pollutants they may contain. In order to see if MICP treatment can also reduce the susceptibility of ENS road lateritic soils to rainwater saturation, this study has treated a Brazilian sample extracted from an ENS road in Espirito do Santo, Brazil, using the MICP bacterium Sporosarcina pasteurii contained within a urea-calcium chloride solution inoculum. Investigation, by means of a Rowe cell, of the post-treatment permeability, to untreated control samples, has shown an average decrease in the vertical coefficient of permeability of 83%, from 1.15 × 10-7 m/s for the untreated control samples, to 1.92 × 10-8 m/s in treated samples.

In developed countries potable water is usually taken for granted, where advanced infrastructure and a strong economy has allowed waterborne diseases (such as cholera and dysentery) to be virtually eradicated. In contrast, developing countries have poor infrastructure, lack development, stability and vibrancy. Consuming untreated, and potentially contaminated, groundwater extracted from shallow wells is the only option. The primary aim of this study was to undertake an extensive field water quality-sampling programme in rural villages throughout Malawi. About 95 % of all the wells tested failed to meet safe drinking water values for untreated water in the wet season, while about 80 % of the wells failed in the dry season. The main forms of contamination emanate from bacteriological and physical constituents. As noted in the United Nations post-2015 water agenda, water quality is just as important as water quantity—the two are inextricably linked. Hence, there is currently a great need to develop more appropriate, cost-effective options to treat water; particularly to reduce the 3.5 million deaths related to inadequate water supply and sanitation each year. Subsequently the aim was directed towards investigating a sustainable, yet appropriate, way to treat shallow well water to significantly improve quality. The most suitable method to remove coliforms and turbidity from water is via the process of coagulation, using aluminium sulphate (alum) or ferric sulphate (ferric). The limited availability and relative expense of these chemicals has led to other more appropriate indigenous coagulants being sought for developing countries. Natural plant extracts have been available for water purification for many centuries. However, the science and engineering application of the use of plant extracts have not really been developed. To start to address this, Leeds Beckett University and the University of Malawi—The Polytechnic have shown that a locally available plant extract, Moringa oleifera, which grows wild throughout rural villages in developing countries, can be used to improve water quality in the order of 80–94 %. The flocculent capacity of M. oleifera is closely comparable to that of a well-established chemical coagulant, alum.

Legionnaire’s disease presents a significant public health risk, yet current monitoring methods remain reactive. Traditional methods involve engineers conducting monthly site visits to collect temperature data from sentinel outlets. While effective, this approach has significant environmental and financial costs due to frequent travel. The rise of Internet of Things (IoT) technology has enabled remote monitoring across various industries, including water management. By transitioning to remote monitoring, this reduces annual site visits from twelve to one, which significantly cuts carbon emissions, water wastage, time and hence costs. This study presents the findings of two independent case studies assessing the environmental and operational impacts of implementing IoT-enabled remote monitoring. The first case study evaluates five sites (A to E). For instance, results from Site A indicating that replacing on-site monitoring with remote systems can reduce CO₂ emissions by 1,993 kg annually—a 96% decrease—alongside fuel cost savings of approximately £1,020. When extrapolated across all Aquatrust monitoring sites, requiring extensive travel, potential annual savings reach 49 tonnes of CO₂ and £24,500. The second case study, based on four representative outlet locations typical to these sites, shows a 90% reduction in water wastage, saving approximately 9,843 litres per year. Together, the findings highlight the significant sustainability and efficiency benefits of remote monitoring, including reduced manual intervention, improved regulatory compliance, and enhanced predictive maintenance enabled by continuous data collection. Additionally, IoT-driven systems improve efficiency by reducing manual testing and maintenance costs while ensuring compliance with water safety regulations. Furthermore, continuous data feeds enable trend analysis, allowing for predictive maintenance and early intervention. However, despite the clear benefits, challenges such as initial implementation costs, data security concerns, and industry resistance must be addressed. Nevertheless, pilot studies and regulatory incentives can facilitate a broader adoption. This approach represents a transformative step in Legionella risk management, offering scalable solutions for both industrial and domestic applications. Future research should focus on optimising deployment strategies and addressing industry-specific challenges, ensuring technology and sustainability continue to drive advancements in water hygiene management.

It is estimated that broken water pumps impact 62 million people in sub-Saharan Africa. Over the last 20 years, broken handpumps have represented US$1·2–1·5 billion of lost investment in this region, with 30–40% of rural water systems failing prematurely. While the contributory factors are complex and multi-faceted, the authors consider that improved post-construction monitoring strategies for remote water projects, which rely on smart pumps to monitor operational performance in place of physical site visits, may address some of these problems and help reduce the heavy time and resource demands on stakeholders associated with traditional monitoring strategies. As such, smart pumps could play a significant role in improving project monitoring and might subsequently help deliver universal access to safe and affordable drinking water by 2030, which constitutes one of the key targets of United Nations sustainable development goal 6 and is embedded in some national constitutions.

The powder obtained from the seeds of the Moringa oleifera tree has been shown to be an effective primary coagulant for water treatment. When the seeds are dried, dehusked, crushed and added to water, the powder acts as a coagulant binding colloidal particles and bacteria to form agglomerated particles (flocs), which settle allowing the clarified supernatant to be poured off. Very little research has been undertaken on the parameters affecting the effectiveness of M. oleifera, especially in Malawi, for purification of drinking water and there is a great need for further testing in this area. Conclusive data needs to be compiled to demonstrate the effects of various water parameters have on the efficiency of the seeds. A parametric study was undertaken at Leeds Metropolitan University, UK, with the aim to establish the most appropriate dosing method; the optimum dosage for removal of turbidity; the influence of pH and temperature; together with the shelf life of the M. oleifera seeds. The study revealed that the most suitable dosing method was to mix the powder into a concentrated paste, hence forming a stock suspension. The optimum M. oleifera dose, for turbidity values between 40 and 200 NTU, ranged between 30 and 55 mg/l. With turbidity set at 130 NTU and a M. oleifera dose within the optimum range at 50 mg/l, pH levels were varied between 4 and 9. It was discovered that the coagulant performance was not too sensitive to pH fluctuations when conditions were within the optimum range. The most efficient coagulation, determined by the greatest reduction in turbidity, occurred at pH 6.5. Alkaline conditions were overall more favourable than acidic conditions; pH 9 had an efficiency of 65% of optimum, whilst at pH 5 the efficiency dropped to around 55%. The efficiency further dropped at pH 4, where the powder only produced results of around 10% of optimum conditions. A temperature range of 4–60 °C was studied in this research. Colder waters (<15 °C) were found to hinder the effectiveness of the coagulation process. The higher the temperature the more effective was the coagulation. It was also found that the age of the seeds, up to 18 months, did not have any noticeable effect on dose level and percentage reduction in turbidity, although at 18 months the seeds had a narrower dosing range to produce near-optimum reduction. Seeds aged 24 months showed a significant decline in coagulant efficiency.

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A research project was commissioned to investigate the performance of Moringa oleifera compared with that of aluminium sulphate (Al2(SO4)3) and ferric sulphate (Fe2(SO4)3), termed alum and ferric respectively. A series of jar tests was undertaken using model water, different raw water sources and hybrid water containing a mixture of both of these types of water. The model water consisted of deionised water spiked with Escherichia coli (E. coli) at 104 per 100 ml and turbidity (146 NTU) artificially created by kaolin. Results showed that M. oleifera removed 84% turbidity and 88% E. coli, whereas alum removed greater than 99% turbidity and E. coli. Low turbidity river water (<5 NTU), with an E. coli count of 605 colony forming units (cfu)/100 ml was treated with M. oleifera and ferric. Results showed an 82% and 94% reduction in E. coli for M. oleifera and ferric respectively. Tests on turbid river water of 45 NTU, with an E. coli count of 2650 cfu/100 ml, showed a removal of turbidity of 76% and E. coli reduction of 93% with M. oleifera. The equivalent reductions for alum were 91% and 98% respectively. Highly coloured reservoir water was also spiked with E. coli (104 cfu/100 ml) and turbidity (160 NTU) artificially created by kaolin; termed hybrid water. Under these conditions M. oleifera removed 83% colour, 97% turbidity and reduced E. coli by 66%. Corresponding removal values for alum were 88% colour, 99% turbidity and 89% E. coli, and for ferric were 93% colour, 98% turbidity and 86% E. coli. Tests on model water, using a secondary treatment stage sand filter showed maximum turbidity removal of 97% and maximum E. coli reduction of 98% using M. oleifera, compared with 100% turbidity and 97% E. coli for alum. Although not as effective as alum or ferric, M. oleifera showed sufficient removal capability to encourage its use for treatment of turbid waters in developing countries.

A study was conducted in Blantyre, Chiradzulu and Mulanje districts in Malawi to determine the biological, chemical and physical drinking water quality from shallow wells. An in situ membrane filtration test kit (Paqualab 50) was used to determine the microbiological quality of water and a photometer was used for the chemical analyses. Water samples were collected from 21 covered/protected and five open/unprotected shallow wells at four different times in a year to determine the change in quality with different seasons. The results of microbiological analysis show that the drinking water quality is very poor, i.e. grossly polluted with faecal matter. Total coliform (TC) and faecal coliform (FC) values in the wet season (February and April, 2006) were much higher than those in the dry season (August and October, 2005). In terms of total coliform, the results show that approximately 80% of the shallow wells tested in the dry season and 100% of the wells in the wet season did not meet the drinking water quality temporary guidelines, set by the Ministry of Water Development - MoWD (2003) [Ministry of Water Development - MoWD, 2003. Government of Malawi, Devolution of functions of assemblies, Guidelines and standards], of a maximum of 50 TC/100 ml for untreated water. Approximately 50% of the wells failed to meet the faecal coliform drinking water guideline of 50 FC/100 ml in the dry season while this figure had increased to 94% of the wells failing to meet the standard in the wet season. Covered wells were not as grossly contaminated as open wells but all of the wells tested failed the MoWD standards in at least one sample. Chemical analyses results were within the drinking water guideline and variations during seasons were insignificant. pH values were within the guidelines in the dry season except for Mulanje district where on average 45% of the wells had pH values below the lower limit of 6.0. In the wet season 50% of the samples had pH values below 6.0. Turbidity values were within the guideline for all covered wells in the dry season, while about 22% had turbidity values greater than the guideline of 25 NTU in the wet season. From these results it is very clear to see that the drinking water from the shallow wells tested, in southern districts of Malawi, is grossly contaminated microbiologically, with this contamination becoming worse in the wet season. Crown Copyright © 2007.