SuSanA - Forum Kunena Site Syndication http://forum.susana.org/ Wed, 29 Mar 2017 18:53:58 +0000 Kunena 1.6 http://forum.susana.org/components/com_kunena/template/default/images/icons/rss.png SuSanA - Forum http://forum.susana.org/ en-gb How to deal with trash in pits - TRASH EXCLUSION - by: FrancisdelosReyes http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/20974-how-to-deal-with-trash-in-pits-trash-exclusion#20974 http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/20974-how-to-deal-with-trash-in-pits-trash-exclusion#20974
Options for dealing with trash during pit emptying
The main challenge in mechanized pit emptying is dealing with trash. Trash, such as large pieces of clothing, rope-type materials, bottles, shoes, etc., can clog any tube-based mechanical approach, if the material is bigger than the tube. Note that the tube is limited to around 10-12 cm in diameter, if it is to access through the squat holes or the pedestal. Trash clogs other human-powered machines such as the Gulper I and II.

There are several approaches to deal with trash in pit latrines. Most pit emptiers who use a machine either accept clogging as something that occurs, and try to minimize the downtime due to clogging. Others, such as those in Blantyre, Malawi, use a “fluidization” method, followed by manual “fishing” to remove the trash using manually operated hooks. This approach is messy and time consuming. “Fishing” can take hours, even half a day, while the subsequent pumping by vacuum pumps take just minutes (Chirwa, Personal communication). The trash in pit latrines is covered in faecal material, and comes in many forms and sizes, making manual removal unhygienic. A third approach is to “macerate” or somehow reduce the size of trash before they enter the hose or tube. To our knowledge, there has not been a single successful application of this technology in real pits. This is because high rotational speeds and a large amount of energy would be needed to chop up material such as cloth, or trash like jeans, shoes, or bottles. A fourth approach is to use screens to minimize clogging. Screens can increase the time between complete clogging, but will still need to be cleaned periodically.

The case for trash exclusion
Leaving the trash behind in the pit avoids all these issues. There is no clogging, no fishing, no fluidization needed (which requires addition of large amounts of water), and no messy trash outside the pit that needs to be handled and disposed. There is no need for additional energy for chopping or macerating trash.

What happens to the trash left behind? One option is to leave it there. This will decrease the subsequent working volume of the pit. Thus the homeowners will need more frequent pit emptying, which will increase their costs. The other option is for the homeowner to request removal of the trash left behind. Since the contract is for removal of faecal material, this additional service should also be additional cost to the homeowner. In both cases, the higher costs for dealing with trash will lead to the change in behavior that is needed- for users to stop using the pit latrine as a trash disposal system. It should be noted that the second option – subsequent removal of the trash that was left behind- will be likely a manual process, until a mechanical option is developed. The costs for removing the trash should be a function of the amount of trash in the pit, again directly incentivizing behavioural change.

Separating the trash from faecal material makes downstream treatment of faecal sludge easier. Current FS treatment technologies, such as anaerobic digestion, composting, fermentation, black soldier fly, vermicomposting, and supercritical water oxidation, all require the pre- removal of inorganics such as plastic, clothing, glass bottles, metals, etc. Technologies such as LaDePa would also benefit if trash were not present, as it would remove the need for the trash removal step that requires energy. If only faecal sludge needs to be treated, then needed steps, such as pathogen inactivation, become more economical and effective, as the volume of material to be treated is reduced. Other reuse options become more feasible. These include conversion technologies to energy or high-value materials (such as long-chain acids or biofuels). Note that the cost of removing trash is already included in the pit emptying step, and eliminated from the treatment step.

Separating the trash will lead to efficiencies in collection, since faecal sludge volumes would be lower. The separated trash can be collected separately and transported to a landfill or other trash management facility that is possibly in a different part of town. Alternatively, the trash can be disposed of in a trash pit within the homeowner’s property. In any case, the trash management system can be optimized to lower costs of dealing with trash.

Conclusions
The removal of only faecal material during pit emptying, and leaving the trash in the pit, is a new approach that has inherent advantages. It is realistic, solves many pit emptying problems, and makes downstream handling and treatment of faecal sludge and trash easier, more hygienic, and more cost-effective.]]>
Faecal sludge transport (including emptying of pits and septic tanks) Tue, 21 Mar 2017 20:24:00 +0000
Re: Lively discussion on 'fishing' of rubbish from pit latrines at WEDC - by: FrancisdelosReyes http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/14842-lively-discussion-on-fishing-of-rubbish-from-pit-latrines-at-wedc#20973 http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/14842-lively-discussion-on-fishing-of-rubbish-from-pit-latrines-at-wedc#20973
Fishing is something that has been on our minds.

Below is a paper that attempts to look at how to deal with trash. I would say that since we submitted this paper, we have formulated a new approach which we described at FSM4 in Chennai. I will discuss that in a later post.


washdev.iwaponline.com/content/7/1/85

Trash removal methods for improved mechanical emptying of pit latrines using a screw auger

Tracey Sisco, Tate Rogers, Walt Beckwith, Willy Chipeta, Rochelle Holm, Christopher A. Buckley, Francis L. de los Reyes
Published March 2017, 7 (1) 85-91; DOI: 10.2166/washdev.2017.106
Abstract

Trash in pit latrines is one of the largest challenges facing pit emptying technologies, including the powered auger (the Excrevator), developed for improved emptying in lower- and lower-middle income countries. This study focused on two trash removal methods in conjunction with pit emptying by the Excrevator: (1) simultaneous removal of trash with sludge and (2) manual trash removal prior to sludge removal. Simultaneous removal was tested by adding to the inlet of the Excrevator system two cutting heads designed to reduce the size of trash particles before entering the pipe and auger. Laboratory testing indicated that the auger will not provide the rotational speeds necessary for proper maceration of fibrous materials such as clothing, indicating that a separate maceration unit with higher rotational methods may be more appropriate. Four manual trash removal mechanisms were designed to improve on existing manual trash ‘fishing’ tools such as iron rods with fixed hooks. Two of these tools (the ‘claw’ and the ‘hook’) showed promising laboratory results and were subsequently field tested in Mzuzu, Malawi. Both tools proved more efficient than the current tools used in the field and have potential for use in Malawi.

washdev.iwaponline.com/content/7/1/85]]>
Faecal sludge transport (including emptying of pits and septic tanks) Tue, 21 Mar 2017 20:19:15 +0000
Re: Solutions for pit desludging and sludge management in low income urban settlements in Malawi (Mzuzu University) - and policy issues - by: rochelleholm http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/6138-solutions-for-pit-desludging-and-sludge-management-in-low-income-urban-settlements-in-malawi-mzuzu-university-and-policy-issues?limit=12&start=24#20961 http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/6138-solutions-for-pit-desludging-and-sludge-management-in-low-income-urban-settlements-in-malawi-mzuzu-university-and-policy-issues?limit=12&start=24#20961
Characterization of pit latrines to support design and selection of emptying tools in peri-urban Mzuzu, Malawi.

Chiposa, R., Holm, R. H., Munthali, C., Chidya, R. C. G. and de los Reyes III, F. L.
Journal of Water, Sanitation and Hygiene for Development, 2017, 07(1), pages 151-155.
DOI: 10.2166/washdev.2017.096
washdev.iwaponline.com/content/7/1/151

ABSTRACT
The urban areas of many low-income countries must balance a rising demand for pit latrines for household sanitation provision against limitations in space, resulting in a need for pit latrine emptying services. This study was undertaken in the peri-urban neighborhood of Area 1B in the city of Mzuzu, Malawi, to examine the characteristics of household pit latrines for designing and selecting pit latrine emptying tools. We used 150 structured household surveys and field observations. From this, a subset was selected and 30 manual cone penetrometer tests were conducted at full latrines. Chemical oxygen demand analysis was also performed for 14 pit latrines. The results indicated that in addition to serving as a disposal for fecal matter, 90% of households also used pit latrines for domestic waste. Only 10% of the studied pit latrines were lined. The filling rate in the study area is calculated to be about three years, and no respondents reported previous emptying. It is suggested pit latrine emptying technology development focuses on a maximum tool diameter of 10 cm to fit through the keyhole (squat hole) and height of 146 cm to fit inside the superstructure, as well as supporting unlined pits and the ability to pump trash.]]>
Faecal sludge transport (including emptying of pits and septic tanks) Tue, 21 Mar 2017 03:46:53 +0000
Re: Solutions for pit desludging and sludge management in low income urban settlements in Malawi (Mzuzu University) - and policy issues - by: rochelleholm http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/6138-solutions-for-pit-desludging-and-sludge-management-in-low-income-urban-settlements-in-malawi-mzuzu-university-and-policy-issues?limit=12&start=24#20770 http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/6138-solutions-for-pit-desludging-and-sludge-management-in-low-income-urban-settlements-in-malawi-mzuzu-university-and-policy-issues?limit=12&start=24#20770
Designing local solutions for emptying pit latrines in low-income urban settlements (Malawi)
by W.C. Chipeta, R.H. Holm, J.F. Kamanula, W.E. Mtonga and F.L. de los Reyes III
Physics and Chemistry of the Earth, Parts A/B/C
dx.doi.org/10.1016/j.pce.2017.02.012

Abstract
A lack of effective options in local technology poses challenges when onsite household sanitation facilities are eventually filled to capacity in unplanned settlement areas within Mzuzu City, located in northern Malawi. Vacuum trucks currently dominate the market but focus on emptying septic tanks in the more easily accessible planned settlement areas, rather than servicing the pit latrines common in unplanned settlement areas. As a result, households in the unplanned settlement areas within Mzuzu rely primarily on manual pit emptying (i.e., shoveling by hand) or digging a new pit latrine. These practices have associated health risks and are limited by space constraints. This research focused on filling the technological gap through the design, development, and testing of a pedal powered modified Gulper pump using locally available materials and fabrication. A modified pedal powered Gulper technology was developed and demonstrated to be capable of lifting fecal sludge from a depth of 1.5 m with a mean flow rate of 0.00058 m3/s. If the trash content was low, a typical pit latrine with a volume of 1–4 m3 could be emptied within 1–2 h. Based on the findings in our research Phase IV, the pedal powered Gulper modification is promising as a potential emptying technology for lined pit latrines in unplanned settlement areas. The success rate of the technology is about 17% (5 out 30 sampled lined pit latrines were successful) and reflects the difficulty in finding a single technology that can work well in all types of pit latrines with varying contents. We note that cost should not be the only design criteria and acknowledge the challenge of handling trash in pit latrines.

To help you access the full article, it is open access, please visit www.sciencedirect.com/science/article/pii/S1474706516300523 .]]>
Faecal sludge transport (including emptying of pits and septic tanks) Wed, 08 Mar 2017 03:58:13 +0000
Re: Emptying of sludge - How can we know the consistency of the fecal sludge during the emptying if it can be pumped or not? - by: ddiba http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/20482-emptying-of-sludge-how-can-we-know-the-consistency-of-the-fecal-sludge-during-the-emptying-if-it-can-be-pumped-or-not#20516 http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/20482-emptying-of-sludge-how-can-we-know-the-consistency-of-the-fecal-sludge-during-the-emptying-if-it-can-be-pumped-or-not#20516
In the case of Kampala-Uganda, vacuum truck operators usually have an idea of what sludge consistency to expect in particular areas but what I have seen them do a lot also is to pour water in pits so as to make the sludge more workable before pumping it out.

Regards,
Daniel]]>
Faecal sludge transport (including emptying of pits and septic tanks) Mon, 20 Feb 2017 10:10:48 +0000
Re: Emptying of sludge - How can we know the consistency of the fecal sludge during the emptying if it can be pumped or not? - by: kevintayler http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/20482-emptying-of-sludge-how-can-we-know-the-consistency-of-the-fecal-sludge-during-the-emptying-if-it-can-be-pumped-or-not#20509 http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/20482-emptying-of-sludge-how-can-we-know-the-consistency-of-the-fecal-sludge-during-the-emptying-if-it-can-be-pumped-or-not#20509
First, I would say that, in addition to septic tanks, many leach pits are pumpeable. Experience in Indonesia shows that there is sometimes a need to mix some water with the pit contents before pumping it and it is possible that some hard consolidated sludge remains in the bottom of pits (and septic tanks) that have not been pumped for some time. The research from e Thekwini in South Africa shows that some dry pit latrines contain faecal sludge that cannot be pumped but there are other places in Africa, for instance Dakar, where septage has a high water content and certainly can be pumped.

Perhaps the best way to make a quick initial assessment is to assess what is already happening. Do vacuum tankers operate and if so what does the material that they discharge look like - is it thick or thin? Of course, there is always the possibility that they are only taking the top layer from the sludge in the tank/pit but observation of existing practice and talking to tanker operators and manual emptiers will give an idea of the existing situation]]>
Faecal sludge transport (including emptying of pits and septic tanks) Sun, 19 Feb 2017 20:42:05 +0000
Re: Emptying of sludge - How can we know the consistency of the fecal sludge during the emptying if it can be pumped or not? - by: JKMakowka http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/20482-emptying-of-sludge-how-can-we-know-the-consistency-of-the-fecal-sludge-during-the-emptying-if-it-can-be-pumped-or-not#20503 http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/20482-emptying-of-sludge-how-can-we-know-the-consistency-of-the-fecal-sludge-during-the-emptying-if-it-can-be-pumped-or-not#20503 Faecal sludge transport (including emptying of pits and septic tanks) Sun, 19 Feb 2017 06:23:43 +0000 Re: Emptying of sludge - How can we know the consistency of the fecal sludge during the emptying if it can be pumped or not? - by: goeco http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/20482-emptying-of-sludge-how-can-we-know-the-consistency-of-the-fecal-sludge-during-the-emptying-if-it-can-be-pumped-or-not#20500 http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/20482-emptying-of-sludge-how-can-we-know-the-consistency-of-the-fecal-sludge-during-the-emptying-if-it-can-be-pumped-or-not#20500
In my view would be nice to have input from participants representing innovations taking place in this area... there are a range of these described in this forum, some funded by benefactors who I'm sure would like to see information flow.

cheers
Dean]]>
Faecal sludge transport (including emptying of pits and septic tanks) Sat, 18 Feb 2017 22:08:51 +0000
Re: Emptying of sludge - How can we know the consistency of the fecal sludge during the emptying if it can be pumped or not? - by: JKMakowka http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/20482-emptying-of-sludge-how-can-we-know-the-consistency-of-the-fecal-sludge-during-the-emptying-if-it-can-be-pumped-or-not#20499 http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/20482-emptying-of-sludge-how-can-we-know-the-consistency-of-the-fecal-sludge-during-the-emptying-if-it-can-be-pumped-or-not#20499 For septic tanks there is usually enough liquid to pump the majority of the sludge, but it might require some manual mixing and trying to break up the often consolidated sludge bottom.

Other on-site systems like pit latrines you can rarely pump, except maybe by adding quite a lot of water and mixing before pumping.]]>
Faecal sludge transport (including emptying of pits and septic tanks) Sat, 18 Feb 2017 06:02:05 +0000
Emptying of sludge - How can we know the consistency of the fecal sludge during the emptying if it can be pumped or not? - by: andriamanjakagael http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/20482-emptying-of-sludge-how-can-we-know-the-consistency-of-the-fecal-sludge-during-the-emptying-if-it-can-be-pumped-or-not#20482 http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/20482-emptying-of-sludge-how-can-we-know-the-consistency-of-the-fecal-sludge-during-the-emptying-if-it-can-be-pumped-or-not#20482 I have a subject which I'd like have your opinion: ''How can we know the consistency of the fecal sludge during the emptying if it can be pumped or not?''
Thanks]]>
Faecal sludge transport (including emptying of pits and septic tanks) Fri, 17 Feb 2017 08:51:35 +0000
Re: Solutions for pit desludging and sludge management in low income urban settlements in Malawi (Mzuzu University) - and policy issues - by: rochelleholm http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/6138-solutions-for-pit-desludging-and-sludge-management-in-low-income-urban-settlements-in-malawi-mzuzu-university-and-policy-issues?limit=12&start=24#20352 http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/6138-solutions-for-pit-desludging-and-sludge-management-in-low-income-urban-settlements-in-malawi-mzuzu-university-and-policy-issues?limit=12&start=24#20352
Pit Latrine Fecal Sludge Resistance Using a Dynamic Cone Penetrometer in Low Income Areas in Mzuzu City, Malawi
by: Charles F. C. Chirwa, Ralph P. Hall, Leigh-Anne H. Krometis, Eric A. Vance, Adam Edwards, Ting Guan and Rochelle H. Holm
Int. J. Environ. Res. Public Health 2017, 14(2), 87; doi:10.3390/ijerph14020087

Abstract
Pit latrines can provide improved household sanitation, but without effective and inexpensive emptying options, they are often abandoned once full and may pose a public health threat. Emptying techniques can be difficult, as the sludge contents of each pit latrine are different. The design of effective emptying techniques (e.g., pumps) is limited by a lack of data characterizing typical in situ latrine sludge resistance. This investigation aimed to better understand the community education and technical engineering needs necessary to improve pit latrine management. In low income areas within Mzuzu city, Malawi, 300 pit latrines from three distinct areas were assessed using a dynamic cone penetrometer to quantify fecal sludge strength, and household members were surveyed to determine their knowledge of desludging procedures and practices likely to impact fecal sludge characteristics. The results demonstrate that there is a significant difference in sludge strength between lined and unlined pits within a defined area, though sludge hardened with depth, regardless of the pit type or region. There was only limited association between cone penetration depth and household survey data. To promote the adoption of pit emptying, it is recommended that households be provided with information that supports pit emptying, such as latrine construction designs, local pit emptying options, and cost. This study indicates that the use of a penetrometer test in the field prior to pit latrine emptying may facilitate the selection of appropriate pit emptying technology.

To help you access the full article which is open access, please visit www.mdpi.com/1660-4601/14/2/87 .]]>
Faecal sludge transport (including emptying of pits and septic tanks) Sun, 05 Feb 2017 10:01:40 +0000
Re: Time taken for faecal sludge tankers to discharge? - by: kevintayler http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/18932-time-taken-for-faecal-sludge-tankers-to-discharge?limit=12&start=24#20199 http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/18932-time-taken-for-faecal-sludge-tankers-to-discharge?limit=12&start=24#20199
Thanks for this. I am currently in Dehradun, India and had a chance to observe a tanker discharging into a sewer on Friday. The tanker capacity was 4000 litres and the outlet was 100mm but they connected a 75m hose to the outlet and dropped the hose into the sewer. That would have increased the head at the end of the pipe but on the other hand there would have been friction in the pipe. The tanker took about 3 minutes and 30 seconds to empty the tanker (assuming it was full which may not have been the case). That equates to about 20 litres per second which is in line with theoretical calculations using orifice theory (albeit ignoring the effect of the hose). The Brazilian experience, along with many of the others referred to in this thread, is that discharge rates are less than this. I think that the overall conclusion is that, whatever the theory says, there is no substitute for recording actual discharge rates - thicker sludges may well take longer to discharge.

One point Christoph is that you do not mention the size of the outlet, I would guess 100mm but it would be good to confirm

Regards to all
Kevin]]>
Faecal sludge transport (including emptying of pits and septic tanks) Mon, 23 Jan 2017 03:52:50 +0000
Re: Vacuum truck, vacuum tanker - what is it? Simple definition for lay people reading on Wikipedia? - by: JKMakowka http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/19578-vacuum-truck-vacuum-tanker-what-is-it-simple-definition-for-lay-people-reading-on-wikipedia#20197 http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/19578-vacuum-truck-vacuum-tanker-what-is-it-simple-definition-for-lay-people-reading-on-wikipedia#20197 christoph wrote:

“There are two different ways to mount the pump: either directly on the truck with the vacuum drive powered by the truck motor, or on the trailer with an independent motor. The more complicated trailer mounted version allows the utilisation of both the negative pressure suction side of the pump as well as the positive pressure side to pump sludge over longer distances or lift it higher into the tank.”

The observation is not correct. It is possible to pressure the suction side of the pump as well when powered with the truck motor. Actually I hardly know Vaccum tanker with a pump on a trailer I would say that is less than 5% of the cases.


Yes it is quite uncommon, as with a air vacuum pump it is difficult to build a setup that can also push. Of course technically you can have the same on the truck (for quicker emptying for example), but that wouldn't really increase the possible lift more than maybe a meter difference between the motor and the top of the tank, no? So practically speaking the text in the wiki (which I wrote) is correct, as the point of having it on a trailer would be to move the pump closer to the septic-tank and thus reduce the length and hight-difference of the suction hose. Or am I misunderstanding what you meant?

christoph wrote:

“Due to the inherent suction limitations of all suction pumps, that can only lift a liquid through atmospheric pressure, a theoretical maximum water lift of approximately 10.3 m (33.9 feet) can be reached.[4]“

That is not correct. It should be.

The typical maximum lift depends on the equipment (vaccum pump) and the material to be transported. The mixture of water/sludge and air (to be controlled by the operator) reduces the density of water/sludge and a theoretical water lift above the clean water lift limit is possible. In practical operation lift differences of over 15 m will seldom be possible. This limits as well the length of the hose. Only in limited cases a hose larger than 50 m will be used.


Can you explain that a bit better? Am I guessing right that the higher density of the sludge solids is not so significant, so that by adding air into the mix the overall density of the sludge/air mix can be brought down significantly below that of pure water?
I always thought adding air was only a way of offset other losses, not actually to increase the overall lift above the theoretical limit of water.
Edit: I changed the text a bit to explain this better. However I also don't have a good source for this.]]>
Faecal sludge transport (including emptying of pits and septic tanks) Sun, 22 Jan 2017 21:33:50 +0000
Re: Vacuum truck, vacuum tanker - what is it? Simple definition for lay people reading on Wikipedia? - by: christoph http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/19578-vacuum-truck-vacuum-tanker-what-is-it-simple-definition-for-lay-people-reading-on-wikipedia#20196 http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/19578-vacuum-truck-vacuum-tanker-what-is-it-simple-definition-for-lay-people-reading-on-wikipedia#20196 I don´t have the references on hand, therefore I did not change anything in Wikipedia. I try to put some aspects here from the page so that you can use or discard them without changing Wikipedia

General

A vacuum truck or vacuum tanker is a type of tank truck that has a vaccum pump and a vaccum tank, designed to pneumatically succion liquids, sludges (such as fecal sludge) or slurries or sand/water mixture without the contact of any mechanical equipment. They are mainly used to transport sanitary waste (human excreta mixed with water, e.g. from on-site septic tanks) as well as for some industrial liquids or slurries and equipped with a high pressure pump they are used to clean out sewers from sand.
The material has to be transported to a treatment or disposal site.

In the text

Pumps:
“There are two different ways to mount the pump: either directly on the truck with the vacuum drive powered by the truck motor, or on the trailer with an independent motor. The more complicated trailer mounted version allows the utilisation of both the negative pressure suction side of the pump as well as the positive pressure side to pump sludge over longer distances or lift it higher into the tank.”

The observation is not correct. It is possible to pressure the suction side of the pump as well when powered with the truck motor. Actually I hardly know Vaccum tanker with a pump on a trailer I would say that is less than 5% of the cases.

Suction lines… Better .. suction hoses?

“Due to the inherent suction limitations of all suction pumps, that can only lift a liquid through atmospheric pressure, a theoretical maximum water lift of approximately 10.3 m (33.9 feet) can be reached.[4]“

That is not correct. It should be.

The typical maximum lift depends on the equipment (vaccum pump) and the material to be transported. The mixture of water/sludge and air (to be controlled by the operator) reduces the density of water/sludge and a theoretical water lift above the clean water lift limit is possible. In practical operation lift differences of over 15 m will seldom be possible. This limits as well the length of the hose. Only in limited cases a hose larger than 50 m will be used.

I hope that helps a bit.
Regards
Christoph]]>
Faecal sludge transport (including emptying of pits and septic tanks) Sun, 22 Jan 2017 17:17:46 +0000
Re: Time taken for faecal sludge tankers to discharge? - by: christoph http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/18932-time-taken-for-faecal-sludge-tankers-to-discharge?limit=12&start=24#20194 http://forum.susana.org/component/kunena/99-faecal-sludge-transport-including-emptying-of-pits-and-septic-tanks/18932-time-taken-for-faecal-sludge-tankers-to-discharge?limit=12&start=24#20194 just some quick comments.
Background: We (Rotária do Brasil) operate 3 tankers and we are part of an association for sludge emptying with 26 tankers in southern Brazil. We operate at one treatment plant.

• The regular discharge time for a tanker of 8 – 9 m³ is about 15 min.. quite similar to the practical numbers mentioned here.

• What is “pressure out”? Normally a tanker empties by gravity, that is better for the equipment and uses less gas. If needed there is the possibility to pressure up the vaccum tank in order to “pressure out” the liquid quicker or if you have to empty against a small difference in level. But that procedure is not very well accepted as it is “stressfull” for the equipment, so it is done only in special situations.

Hope that complements the picture.

Regards
Christoph]]>
Faecal sludge transport (including emptying of pits and septic tanks) Sun, 22 Jan 2017 15:50:38 +0000