Motorised Emptying and Transport

Motorized emptying and transport refers to a vehicle equipped with a motorized pump and a storage tank for emptying and transporting faecal sludge and urine. Humans are required to operate the pump and manoeuvre the hose, but sludge is not manually lifted or transported.

A truck is fitted with a pump which is connected to a hose that is lowered down into a tank (e.g., Septic Tank) or pit, and the sludge is pumped up into the holding tank on the vehicle. This type of design is often referred to as a vacuum truck. Alternative motorized vehicles or machines have been developed for densely populated areas with limited access. Designs such as the Vacutug, Dung Beetle, Molsta or Kedoteng carry a small sludge tank and a pump and can negotiate narrow pathways.

Design Considerations

Generally, the storage capacity of a vacuum truck is between 3 and 12 m3. Local trucks are commonly adapted for sludge transport by equipping them with holding tanks and vacuums. Modified pick-ups and tractor trailers can transport around 1.5 m3, but capacities vary. Smaller vehicles for densely populated areas have capacities of 500 to 800 L. These vehicles use, for example, two-wheel tractor or motorcycle based drives and can reach speeds of up to 12 km/h. Pumps can usually only suck down to a depth of 2 to 3 m (depending on the strength of the pump) and must be located within 30 m of the pit. In general, the closer the vacuum pump can be to the pit, the easier it is to empty.

Appropriateness

Depending on the Collection and Storage technology, the sludge can be so dense that it cannot be easily pumped. In these situations it is necessary to thin the solids with water so that they flow more easily, but this may be inefficient and costly. Garbage and sand make emptying much more difficult and clog the pipe or pump. Multiple truckloads may be required for large septic tanks.
Although large vacuum trucks cannot access areas with narrow or non-driveable roads, they remain the norm for municipalities and sanitation authorities. These trucks can rarely make trips to remote areas (e.g., in the periphery of a city) since the income generated may not offset the cost of fuel and time. Therefore, the treatment site must be within reach from the serviced areas.
Transfer Stations and adequate treatment are also crucial for service providers using small-scale motorized equipment. Field experiences have shown that the existing designs for dense urban areas are limited in terms of their emptying effectiveness and travel speed, and their ability to negotiate slopes, poor roads and very narrow lanes. Moreover, demand and market constraints have prevented them from becoming commercially viable. Under favourable circumstances, small vehicles like the Vacutug are able to recover the operating and maintenance costs. However, the capital costs are still too high to sustainably run a profitable business.
Both the sanitation authority and private entrepreneurs may operate vacuum trucks, although the price and level of service may vary significantly. Private operators may charge less than public ones, but may only afford to do so if they do not discharge the sludge at a certified facility. Private and municipal service providers should work together to cover the whole faecal sludge management chain. 

Health Aspects/Acceptance 

The use of a vacuum truck presents a significant health improvement over manual emptying and helps to maintain the Collection and Storage technology. Still, truck operators are not always accepted by the community and may face difficulties with finding appropriate locations to dump the collected sludge.

Operation & Maintenance

Most pump trucks are manufactured in North America, Asia or Europe. Thus, in some regions it is difficult to locate spare parts and a mechanic to repair broken pumps or trucks. New trucks are very expensive and sometimes difficult to obtain. Therefore, older trucks are often used, but the savings are offset by the resulting high maintenance and fuel costs that can account for more than two thirds of the total costs incurred by a truck operator. Truck owners must be conscientious to save money for the purchase of expensive replacement parts, tires and equipment. The lack of preventive maintenance is often the cause for major repairs.The addition of chemical additives for desludging is not recommended because they tend to corrode the sludge tank.

References

Further Readings

  • Cover image of a reference book or miscellany.

    TILLEY, E.; ULRICH, L.; LUETHI, C.; REYMOND, P.; SCHERTENLEIB, R.; ZURBRUEGG, C. (2014): Compendium of Sanitation Systems and Technologies (Arabic). 2nd Revised Edition. Duebendorf, Switzerland: Swiss Federal Institute of Aquatic Science and Technology (Eawag). PDF

    This is the Arabic version of the Compendium of Sanitation Systems and Technologies. The Compendium gives a systematic overview on different sanitation systems and technologies and describes a wide range of available low-cost sanitation technologies.

  • Cover image of a reference book or miscellany.

    BOESCH, A.; SCHERTENLEIB, R. (1985): Emptying on-Site Excreta Disposal Systems. Field Tests with Mechanized Equipment in Gaborone (Botswana). Duebendorf: International Reference Centre for Waste Disposal. URL [Accessed: 22.07.2014]. PDF

    This report describes field tests of three prototype pit latrine emptying systems, a hand operated diaphgram pump and two vacuum tankers in regular service in Africa. Numerous sludge samples were taken and their viscosities and compositions measured to establish limits for the types of sludges that can be removed by each system.

  • Cover image of a reference book or miscellany.

    BRIKKE, F.; BREDERO, M. (2003): Linking Technology Choice with Operation and Maintenance in the context of community water supply and sanitation. A reference Document for Planners and Project Staff. Geneva: World Health Organization and IRC Water and Sanitation Centre. URL [Accessed: 30.03.2010]. PDF

    This document is addressed to planners and staff of water supply and sanitation projects on household and community level. The reader is guided through the main steps of informed choices regarding the main proven technologies for water supply, purification and water treatment at household and community level. Each technology is described in a small factsheet, regarding its functioning, actors and their roles, the main operation and maintenance (O&M) requirements and problems, which can occur.

  • Cover image of a reference book or miscellany.

    CHOWDHRY, S.; KONE, D. (2012): Business Analysis of Fecal Sludge Management: Emptying and Transportation Services in Africa and Asia. Seattle: Bill & Melinda Gates Foundation. URL [Accessed: 22.07.2014]. PDF

    This study maps the urban sanitation situation and assesses business and operating models for fecal sludge management in 30 cities across 10 countries in Africa and Asia, specifically focussing on the extraction and transportation market segments.

  • Cover image of a reference book or miscellany.

    EAWAG/SANDEC (Editor) (2008): Faecal Sludge Management. Lecture Notes. Duebendorf: Swiss Federal Institute of Aquatic Science (EAWAG), Department of Water and Sanitation in Developing Countries (SANDEC). URL [Accessed: 23.05.2012]. PDF

    This module pays special attention to the haulage, treatment and reuse or disposal of faecal sludge. It covers both technical and non-technical (socio-cultural, economic, political etc.) aspects and provides practical information on design, financing and planning of faecal sludge treatment plants.

  • Cover image of a reference book or miscellany.

    KONE, D.; STRAUSS, M.; SAYWELL, D. (2007): Towards an Improved Faecal Sludge Management (FSM). Duebendorf: EAWAG/SANDEC. URL [Accessed: 15.12.2010]. PDF

    More than two billion urban dwellers in developing countries use on-site sanitation facilities such as pit latrines, septic tanks and aqua privies for excreta and wastewater disposal. Since on-site sanitation installations will serve the growing urban populations in developing countries for decades to come, increasing faecal sludge quantities will have to be managed. Proper faecal sludge management (FSM) is the important link missing in integrated urban sanitation upgrading efforts.

  • Cover image of a reference book or miscellany.

    MONVOIS, J.; GABERT, J.; FRENOUX, C.; GUILLAUME, M. (2010): How to Select Appropriate Technical Solutions for Sanitation. Cotonou and Paris: Partenariat pour le Développement Municipal (PDM) and Programme Solidarité Eau (pS-Eau). URL [Accessed: 19.10.2011]. PDF

    The purpose of this guide is to assist local contracting authorities and their partners in identifying those sanitation technologies best suited to the different contexts that exist within their town. The first part of the guide contains a planning process and a set of criteria to be completed; these assist you in characterizing each area of intervention so that you are then in a position to identify the most appropriate technical solutions. The second part of the guide consists of technical factsheets which give a practical overview of the technical and economic characteristics, the operating principle and the pros and cons of the 29 sanitation technology options most commonly used in sub-Saharan Africa.

  • Cover image of a reference book or miscellany.

    STILL, D.; O RIORDAN, M.; MC BRIDE, A.; LOUTON, B. (2013): Adventures in search of the ideal portable pit-emptying machine. Rugby: Practical Action Publishing. URL [Accessed: 07.08.2013]. PDF

    This article explores the ideal portable pit-emptying machine for South Africa owing to site access constraints. The Water Research Commission of South Africa funded experimental development of a number of technologies designed to fill the gap between large vacuum tankers and manual emptying. This paper describes these attempts.

Case Studies

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    SCHAUB-JONES, D.; EALES, K.; TYERS, L. (2006): Sanitation partnerships. Harnessing their potential for urban on-site sanitation. URL [Accessed: 15.12.2010]. PDF

    The aim of this case study in five African cities was to look closely at the issue, see where partnerships fit into efforts to improve on-site sanitation and understand better what makes them succeed or fail. The ultimate goal is to help those involved in the delivery of sanitation services make more informed decisions about what routes to pursue the outset

  • Cover image of a reference book or miscellany.

    OPEL, A.; BASHAR, M.K. (2013): Inefficient technology or misperceived demand. The failure of Vacutug-based pit-emptying services in Bangladesh. Rugby: Practical Action Publishing. URL [Accessed: 07.08.2013]. PDF

    Demand is growing globally for appropriate technology and viable business solutions to pit-emptying and transportation services. There is a growing body of experiments on technological innovations in different contexts to find an effective solution. However, there is no one technology or business model that can be applied everywhere because of contextual difference and varied demand. A Vacutug-based emptying and transportation service has been introduced in an urban context in Bangladesh by WaterAid. However, this study suggests that despite enormous demand, this mechanical emptying and transportation service has not been successful because of technological inefficiency and other demand-related factors.

Training Material

  • Cover image of a reference book or miscellany.

    PICKFORD, J.; SHAW, R.; WELL (Editor) (1997): Emptying Pit Latrines. Loughborough: Water and Environmental health at London and Loughborough (WELL). URL [Accessed: 26.04.2010]. PDF

    This technical brief describes several possibilities of emptying pit latrines and helps to find the most suitable method.

Important Weblinks

  • http://www.un-habitat.org/ [Accessed: 04.01.2011]

    After studying the situation in slums around the world, UN-HABITAT sought to devise a system that would replace manual pit latrine and septic tank emptying. It commissioned a mechanical system that would be capable of being manufactured locally using readily available components, that would be affordable, easily serviceable, able to operate in narrow passageways where other conventional exhauster vehicles cannot pass, and capable of sucking out dense waste sludge for transportation to a larger tanker vehicle. At the same time it was imperative that excrement be removed as safely as possible without posing further health hazards in slums. Thus in 1995 Manus Coffey and Associates Ltd (MCA) and UN-HABITAT designed and built the first prototype in Ireland: the MK I UN-HABITAT Vacutug.