Talk:Sewage sludge treatment

message: I think there needs to be a distinction made between biosolids and sludge. In an activated sludge process, the solids wasted out of the process are biosolids, the colonies of bacteria that eat waste matter). In a standard process with primary and secondary clarification, the resulting solids are literally sludge, whatever settles out is what you get.
With both processes, the biosolids and sludges are usually digested, anaerobically or aerobically. This is to reduce VOC content and also further the breakdown -or- digestion of organic matter.  Digested biosolids from an activated sludge process are (usually) 12-15 days old, and are nothing but nutrients (phosphorus, nitrogen, ammonia, zinc, potassium, sulphur, manganese, magnesium, iron, copper, calcium, and a host of other yummy ingredients, including trace amounts of heavy metals and other pollutants). The quality and  constituents of digested biosolids largely depends of the community the wastewater was collected from. For example, in a residential suburb, you may derive a very high quality biosolids that can easily be qualified for land application, but in a heavy industrial and urban community, your biosolids may contain much higher concentrations of chemicals and heavy metals, disqualifying their use as a fertilizer.  The level of industrial pre-treatment also plays a large role in the quality of biosolids.
Also, a reason as to why some plants use anaerobic digestion and aerobic digestion needs to be made. For example, the capital cost of an anaerobic system is vastly greater than the cost of an aerobic system, but in the long term, the anaerobic system is more cost efficient. Aerobic systems require air pumped into them, needing power hungry blowers.
After digestion I think there needs to be more descriptions of the dewatering processes, such as:
Sludge Drying Beds
Drying beds consist of long skinny concrete troughs filled with sand, and have an underdrain system. Sludge is allowed to fill the bed, and the water slowly drains through the sand, leaving the solids on top. The sludge may be left to air dry, sometimes for days, resulting in a solid that can be ~80% solids or higher. The purpose of the troughs being skinny is so that a front-end loader drive down the trough and scoop up the dried sludge, leaving the sand intact for the next batch.  The tires of the loader sit on the very short concrete walls between the troughs. Drying beds are a slow dewatering process, and are perfect for plants processing less than 4MGD.
Belt Filter Press
A Belt Filter Press is a carryover from the paper pulp industry. basically, it is a machine that has two belt loops that come together at one point, squeezing the water from the sludge. The solids remain between the belts and are scraped off, usually onto a conveyor. A press feature three main zones, the gravity zone, where the sludge is dropped onto the belt, and a majority of the water is drained via gravity through the belt. The shear zone, where the two belts come together and usually the initial drum that the belts travel around after the gravity zone. A lot of water is squeezed out here. Next is the pressure zone where the belts travel through a series of rollers, placing the belts under extreme pressure. This forces out the last amount of water.  Belt Filter Presses are the workhorses of the dewatering section of most plants because of their ease of use, year round ability to dewater, and relatively low power consumption. The dewatered "cake" scraped off the belts is usually a wet 10% to spongy 18% solids, dry enough to haul in a dump truck.
Plate Filter Press
Similar to a Belt Filter Press, except higher pressures can be obtained and thus, a drier cake in the 25-35% range. This is a slower process than the Belt Filter Press as the Plate Filter Press cannot continually process biosolids. The plate filters must be filled, squeezed together then unloaded.
Centrifuge
A centrifuge is also a carryover, but from multiple industries (mainly food!) and tailored for sludge. basically, there is a large spinning drum, which may reach speeds as high as 20k RPM. Inside, there is a screw which turns at a slightly lower speed than the drum, pushing the driest solids to one end for discharge, and the liquid flows out the drum into the casing for dishcharge. Centrifuges can handle higher flow rates than comparable Belt Filter Presses, and also have drier cake, usually a spongy 18% to crumbly 26-40% solids. Centrifuges consume much more power than a belt filter press, but the savings are seen in lowered hauling costs.
Liquid
Usually only in the smallest plants, sludge is hauled by tanker truck to another facility for dewatering, or some other direct use.
And even after de-watering, you have the disposal methods.
Landfill
Many plants dispose of their de-watered sludge in sanitary landfills (in the U.S.). This option does have its costs, but sometimes there is no other alternative.
Land Application
Depending on the quality of sludge, the dewatered sludge or biosolids can be used as a fertilizer on crops not intended for human consumption.  This is by far the cheapest option, as most municipalites give it away to farmers and some even spread it themselves on the farmers fields at no charge. In the U.S. biosolids must meet "Class B" criteria for land application, which has to do with the levels of contaminates in the biosolids.
Deep Well Injection
Rarely practiced, liquid sludge may be injected deep into the earth.
Given away or sold to consumers
For lawn and garden use. Very stringently drawn rules and regulations govern this practice, ans the only biosolids qualified for this are "Class A" and have had their pathogenic content reduced to near nothing. "Class A" biosolids are made by cooking the "Class B" biosolids cake from the dewatering process.  This is accomplished trhough a variety of means, mainly gas-fired rotating drum ovens, microwaves, and sunlight. The prohibitive cost of this makes it unattainable by most municipalities.
Ocean Dumping
This practice is now illegal in the U.S. and U.S. waters, not sure about the world.
Incineration
Fairly expensive because of the fuel requirement, but incineration reduces biosolids down to about 10% of its original mass and volume, making the ash very cheap to landfill. This is an option when the sludge does not meet the quality requirements for land application or even direct landfilling.
Please feel free to tear this apart. Thanks JAK83 17:37, 5 February 2007 (UTC)
replies: text: Hi. I made the following remark at Biosolids. (Copied from biosolids talk) Not a bad idea. I would rename sewage sludge treatment to just sewage sludge then merge in sludge and make sludge a disamb to include industrial sludge, water treatment sludge, etc. I would leave biosolids as a separate article due to the political and social aspects it has that are not shared by sludges that are not distributed as CFR 503 biosolids. --Justanother 04:41, 10 February 2007 (UTC)

text: Good work here! I may have a few more comments later but for now let me present a different distinction in terms. Although there is not uniformity nationwide, the USEPA seems to make the distinction that sewage sludge that has been further processed for beneficial reuse under CFR Part 503 would be called "biosolids". I think it would serve us well if we went that way. I think that the organic pre-digester treatment sludges you term "biosolids" above could as well be called "biomass" and avoid confusion. How does that sound? --Justanother 06:06, 10 February 2007 (UTC)
thread_title:  sludge vs. biosolids and disposal 

message: The section on disposal should be moved to the sewage sludge page because this article is about treatment, not about disposal. However, when looking at it more closely, one can see that it doesn't actually talk about disposal but also about treatment... Therefore it needs to be integrated into the body of the article, or a different header chosen. I think some of it is dublication, was probably copied from another article. Could someone tidy this up? EvM-Susana (talk) 10:38, 14 January 2015 (UTC)
replies: text:  yes, sounds good to me. EvM-Susana (talk) 19:38, 19 February 2015 (UTC)
thread_title:  Section on disposal does not fit here 

message: A persistent problem with broad concept Wikipedia articles are recurring efforts by special interest editors to inappropriately emphasize emerging technologies. Neutrality requires coverage to accurately reflect present and historical trends. The emerging technologies section of this article is intended to recognize and provide a brief mention of promising technologies; and while there will not be room for a full description of all of them, descriptions of a few broadly successful technologies will ultimately be integrated into the main article as their use becomes widespread. To avoid inappropriately weighting this article with descriptions of little-used treatment methods, I propose to restrict the emerging technologies section to a brief sentence describing those technologies with notability established by a separate article.
In the absence of an alternative organization proposal with appropriately verified notability precedence, I suggest a single alphabetical bullet listing of the emerging technologies by article name to avoid an inappropriately long table of contents unduly weighted toward emerging technologies. I suggest emerging technologies might be considered those applied to less than ten percent of sludge volume and at fewer than ten percent of sludge treatment facilities.Thewellman (talk) 01:46, 19 February 2015 (UTC)
replies: text: I don't really see the problem here. The section on emerging technologies is not very long. Just because a technology has its own page (like the one on Omni-processor) does not mean it is necessarily "notable". The Omni-processor page contains little more than the link to the BBC article and the company's website. I could equally create a separate page on "phosphorus recovery from sewage sludge"... (if I had the time). This suite of technologies is in any case far more advanced than the Omni-processor, see the example of Ostara. It was your idea to move "phosphorus recovery" to the emerging technologies section and now you are saying this section is getting too long. In my opinion it (the phosphorus recovery section) should be at the end of the other treatment technologies. I can't say how many treatment plants use the Ostara process. Of course not 10% on a worldwide scale but neither do 10% of all wastewater treatment plants use enhanced biological phosphorus removal and nevertheless that is a notable technology. So my proposal is to move phosphorus technology away from the emerging technologies section; or otherwise just leave it as is and focus on other problem areas of this article (or of the article on sewage sludge) rather. Time will tell how these emerging technologies will develop. Another alternative is to delete the section on emerging technologies altogether, as I don't think they are important (they could simply be mentioned in one sentence or under See Also). But not to delete the section on phosphorus recovery from sewage sludge, because that one is important and well referenced. I can add more references there, however most of it is in German. EvM-Susana (talk) 19:47, 19 February 2015 (UTC)

text: * The problem has not yet reached critical mass, but your edit causes approximately 10% of this article to be focused on a technology which is not yet economically viable. I anticipate other editors may wish to similarly expand descriptions of emerging technologies. In time, such editing will create an article with disproportionate focus on sludge treatment technologies representing an insignificant fraction of international sewage sludge treatment. I encourage you to compile information into a separate phosphorus recovery article before this article requires thinning of emerging technologies to maintain focus on successful methods. If you don't wish to compile a separate article, you might alternatively create or expand a section of an existing article such as phosphorus recovery or the work you have already done on reuse of excreta. Information from a separate article can be condensed into this article as the technology becomes cost effective. Thewellman (talk) 21:39, 19 February 2015 (UTC)
replies: text:  Let us see what other editors do in future and then we can still re-visit this perceived problem if the part on emerging technologies gets to big. You say the technologies are not yet economically viable - well this doesn't apply to the Ostara process in Canada (they also have installations in Europe). If it wasn't economically viable that company wouldn't sell it. I think it's important that an article on sewage sludge treatment also considers sewage sludge liquor (e.g. digestate) treatment. The section could be restructured to make it clearer that this is sewage sludge liquor treatment. EvM-Susana (talk) 07:44, 20 February 2015 (UTC)
thread_title:  Emerging technologies 

message: Hello, Katana0182 I would like to speak to you and others about how we want to deal with the "biosolids" issue in this article. I am not really in agreement with your recent changes (last paragraph of the lead). The citation for the term biosolids that I had given is the well respected textbook by Metcalf and Eddy. You have only provide one reference from 2002, yet you spoke of "studies". I also don't like the term "sewage treatment industry" - there is no industry, it is simply local governments etc. But I know the whole debate in the US is different than e.g. in Europe. Much more heated over there... You only need to look on the page on sewage sludge and its talk page to see the whole level of controversy there.... I suggest that we tone done the sentences about biosolids, that we move it to further down in the article (take it out of the lead), and generally keep it very short and rather refer to the article on sewage sludge - so that we don't have two pages that explain the issue with biosolids but only one, i.e. the page on sewage sludge. But I think at least once in this article the term "biosolids" needs to be mentioned because of literature (not just the "propaganda literature" but also normal textbooks, like Metcalf and Eddy) use this term. EvM-Susana (talk) 21:24, 23 April 2015 (UTC)
replies: text:  I think I generally agree with these assessments.  Clearly it is true that some see the term "biosolids" as propaganda, and it is also true that it is possible to cite sensible references on this point. However, it is absolutely the case that the term has widespread usage by those involved in the treatment of sewage sludge, so it would be rather ridiculous not to use it here. I think it is fair to keep a line making it clear that some are campaigning against the term, but support the idea of an expanded biosolids page where all the different sides to the debate can set out their views without derailing this page. JMWt (talk) 07:57, 24 April 2015 (UTC)
replies: text:  I have just rearranged that section as a suggestion for resolving this issue.  Thoughts? JMWt (talk) 08:08, 24 April 2015 (UTC)
replies: text:  I like your changes and I have taken it a bit further. I have moved it out of the lead into a new section called terminology (I think it would otherwise get too much weight in the lead). I have also linked there to other relevant pages. OK like this?EvM-Susana (talk) 09:33, 24 April 2015 (UTC)
thread_title:  About the term biosolids 

message: It was suggested above to have a separate biosolids page. At the moment, biosolids redirects to sewage sludge. The curent page on sewage sludge is an absolute mess. It contains the word biosolids on about 80 occasions - so I think that IS a biosolids page already, full of descriptions of the controversies... So I don't see how a separate biosolids page could help - unless we actually rename the sewage sludge page to "biosolids" and create a new sewage sludge page which is purely focussed on the technical aspects. At the moment, I have a similar paragraph about biosolids at the end of the lead section of the "sewage sludge" article but I am wondering if either the same wording that we have used here now should be copied across, or if a terminology section would also be good there. - I guess the whole debate about biosolids fits better on the page of sewage sludge than on the page of sewage sludge treatment - at least that's how it's set up at the moment. EvM-Susana (talk) 09:33, 24 April 2015 (UTC)
replies: text: Maybe it is a "can of worms" which is too complicated to sort out and would require rewriting multiple pages. JMWt (talk) 09:40, 24 April 2015 (UTC)
replies: text:  Thewellman has taken the plunge and created a new page for biosolids. Please see on its talk page for further discussion. We have actually gone full-circle because a separate page on biosolids used to exist but was later re-integrated into the page on sewage sludge. My other concern is what to do about the page on sewage sludge? I think there would be very large sections that would need to be deleted.EvM-Susana (talk) 20:43, 26 April 2015 (UTC)
replies: text: I think the new article is appropriate and balanced and deals principally with the cultural, marketing and quasi-political issues. I believe that all the process and technological and environmental issues should be at "sewage sludge treatment". Where content best lies between "Sewage sludge treatment" and "Biosolids" is a debate worth having, but my strong inclination would be to retain as much as possible in "sewage sludge" and keep "biosolids" relatively compact as a description of a marketing approach.  Velella  Velella Talk   21:45, 26 April 2015 (UTC)
replies: text:  I think the pages on biosolids and sewage sludge treatment are not bad now, but the page on sewage sludge is a desaster... I have tried to improve it bit by bit, but I think one may need a rigorous approach and delete huge parts of the text, as it's either biased, way too detailed, too focussed on examples in the US, using too many poor references like primary research articles, too repetitive and so forth. But who has the time to work on that page? It seems to be abandoned by its original editors, at least I have had no reactions so far for the edits I have done there. EvM-Susana (talk) 22:10, 26 April 2015 (UTC)
thread_title:  Separate Biosolids page? 

message: Can we tidy these references up?  I don't like the split between refs and the further reading section. Also, are there really no good references since the 1970s?  I find that very hard to believe. JMWt (talk) 08:21, 24 April 2015 (UTC)
replies: text: I agree with you. It came about from that method of using notes and references. So it's not technically further reading that is listed there but it is part of the sources. But I don't actually know how to change it? The more recent references are listed under "references". I would delete the "further reading" section but it's not possible because it comes from that method of citing. Help anyone? EvM-Susana (talk) 09:33, 24 April 2015 (UTC)
thread_title:  References 

message: This article needs a paragraph or new section/sub-section describing thermal hydrolysis, a process employed at some sewage treatment plants around the world. I'm not sure where in the article to add this. Suggestions? Moreau1 (talk) 04:24, 20 August 2016 (UTC)
replies: text: Good idea, please go ahead. Add it under emerging technologies? EvMsmile (talk) 13:43, 27 August 2016 (UTC)
replies: text:  Thanks. I added a paragraph. Moreau1 (talk) 00:54, 31 August 2016 (UTC)
replies: text:  Thank you. EvMsmile (talk) 11:37, 4 September 2016 (UTC)
thread_title:  Thermal hydrolysis 

message: I've just come across the new article on sewage waste energy. I don't think it is very good and the term itself is also not well established. I suggest to merge any worthwhile content to here, as it really is about sewage sludge treatment with energy as a side product. EvMsmile (talk) 20:55, 3 January 2017 (UTC)
replies: text:  In my opinion the article sewage waste energy is actually very poor quality. It starts already with a strange title. There is no such thing as "sewage waste"! If anything it is "sewage sludge". I think it should be nominated for deletion and content worth saving should be integrated into here. When the section on "energy from sewage sludge" gets too big, then a spin-off article could be created. EvMsmile (talk) 21:44, 30 January 2017 (UTC)
replies: text: I agree it is a very poor article which seems mostly about promoting companies involved in energy production from sewage sludge. Therefore I agree with EvMsmile and for the avoidance of doubt, I also agreee to the merge here of a well balanced and brief précis. I do not believe that the existing title is appropriate, even for a redirect, and I would advocate its deletion.  Velella  Velella Talk   22:57, 30 January 2017 (UTC)

text:  I don't disagree with your assessment of the quality of the article.  As an inclusionist, I would not initiate deletion; but I have no objection to someone else taking that action.  My objection is to the proposal to merge that poor quality material into this article.  It appears to be an experimental technology warranting, at most, an internal link from this article to a separate article; but if the experimental technology is not notable enough to warrant a separate article, the experimental technology seems unworthy of description in this article. Thewellman (talk) 23:15, 30 January 2017 (UTC)
replies: text:  My suggestion was to take any content worth salvaging from sewage waste energy (but not take the poor quality parts) and to merge that into here, and then to delete the sewage waste energy article. Oh, wait, I looked at it again and there is really very little that can be salvaged! I had originally looked at the references and thought some of them might be worth including (if they are not already there). But now I see that none of the references are actually properly cited in the text but just listed. - I think the article ought to be deleted. Question is for me now: speedy deletion or slow deletion. I guess "slow deletion" would be the way to go.  EvMsmile (talk) 00:47, 31 January 2017 (UTC)
replies: text: I would PROD it just to allow any contrary views to emerge. Some AfDs tend to attract occasional voices that have no knowledge of the topic and judge only by reference count or some other arbitrary test - no criticism of the great majority of AfD particpants implied by that. An uncontested PROD will gently expire in 7 days without fuss. There is absolutely no avenue for a speedy delete.  Velella  Velella Talk   03:07, 31 January 2017 (UTC)
replies: text:  Have added the deletion tag now.EvMsmile (talk) 22:45, 26 February 2017 (UTC)
replies: text:  Have just noticed that an admin disagreed with the PROD and deleted the tag from the article. I have questioned the decision of the admin here in case you are interested. I wonder if you User:Gronk Oz have an opinion on this since you once did some edits on the article sewage waste energy. EMsmile (talk) 19:07, 12 March 2017 (UTC)
replies: text:  Have spoken to that admin and based on his/her advice have placed a redirect on the page sewage waste energy to here. EMsmile (talk) 12:43, 13 March 2017 (UTC)
thread_title: Merge article sewage waste energy to here