SuSanA - Forum Kunena Site Syndication http://forum.susana.org/ Sun, 26 Mar 2017 11:08:27 +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 Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design) - by: BPopov http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20899 http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20899
This is great experiment! Means it is quite a robust system.
Regards
Bogdan]]>
Vermicomposting for various types of waste streams Thu, 16 Mar 2017 21:48:30 +0000
Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design) - by: goeco http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20898 http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20898
cheers
Dean]]>
Vermicomposting for various types of waste streams Thu, 16 Mar 2017 21:34:01 +0000
Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design) - by: BPopov http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20897 http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20897 This all is very very interesting.

How about oils and grease? Do they pose threat for the vermifilter and better removed by grease trap before it? I am asking this since in compost pile grease is quite ok and sometimes used deliberately to heat it up.



Regards,
Bogdan]]>
Vermicomposting for various types of waste streams Thu, 16 Mar 2017 21:24:15 +0000
Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design) - by: goeco http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20872 http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20872 No I don't believe the process releases much heat. Certainly oxidation means generation of heat, but I don't think the wastewater would increase much in temperature during the process because of flow and volumes involved. Although the wastewater influent has a very high biological oxygen demand (BOD), which directly results from dissolved and suspended organics, if actually quantified as organic matter content, this is not much compared with the solids pile. The issue is that the amount of oxygen that water can contain or "dissolve" is very little compared with what is in air. This means that the oxygen needs to be replenished several times in wastewater for aerobic decomposition to be completed, if only taking place in the water. The biological process is that the bacteria degrade the organics in the wastewater and consume oxygen. What little oxygen is dissolved in the water is quickly depleted, rapidly leading to anaerobic conditions unless aeration takes place. I've tried to explain this here. Filtering solids out and providing air to the decomposing bacteria is quite different than decomposition taking place within the water... a big advantage with vermifiltration over traditional wastewater treatment.

However, if the water is already cold the process will inevitably be slow (even slower under anaerobic conditions). This means a capacity issue if the environment is cold for long periods.

By providing ventilated media and wastewater flow with lots of "food" (organics), bacterial slime builds up on the media and consumes the dissolved and suspended organics. I favour the recirculating vermifilter because oxygen will dissolve into the wastewater with each pass. I just don't think that the quantity of organics in the filtered wastewater will be sufficient to generate much heat. The solids pile on the surface of the primary treatment vermifilter would produce some heat but this does not decay rapidly like a compost heap. A normal compost heap decomposes very rapidly from the inside out because there is plenty of air inside it and the heat generated increases the rate of decomposition. The "wet" compost heap on top of the primary treatment vermifilter doesn't have air inside it, it relies on the worms to introduce air from the outside (especially underneath) and so the process is slower. It would generate some heat but maybe not as much as you require to increase rate of decomposition in cold conditions.

Okay, so insulation would be required to ensure the worms don't freeze. However, ventilation shouldn't be required when conditions are cold because there is so little biological activity taking place anyway and the oxygen wouldn't get depleted in the reactor. You could introduce a heat source to generate the required biological activity and treatment level, but I'm thinking you could automate ventilation to open when the sun does shine or when temperature does get above say 5 degrees, you just need capacity because when its cold not much will be happening.

Just some ideas, it doesn't often get below zero degrees C here!]]>
Vermicomposting for various types of waste streams Thu, 16 Mar 2017 09:15:45 +0000
Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design) - by: BPopov http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20845 http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20845
Thanks for the useful input! Yes it would be really intresting for me to build this one in the cold conditions where sometimes I work with -20 C outside for prolonged time during winter. There is not much sun to take into account for the passive ventilation.
Does this process release considerable heat? Probably one can expect more heat from black water vermifilter than from a grey one.
What do we have here a compost pile with a bit of worms or rather worm nest eating up feces with a bit of compost?

Regards,
Bogdan]]>
Vermicomposting for various types of waste streams Tue, 14 Mar 2017 11:50:06 +0000
Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design) - by: goeco http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20842 http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20842
I'm not in a cold climate but was thinking that a well insulated reactor would only require ventilation when it warms up. Very little biological activity would happen say below 6 degrees C so the ventilation system could be set up to switch on once above that temperature. This could be passive, such as convection (a black pipe that warms with the sun and draws air into the reactor), or a small solar panel and fan that runs during the daytime? In small systems I don't think air pipes through the media would be necessary, especially if the media basket has air flow under and around the sides and the media course. However, anything that improves the efficiency of the system is good!

cheers
Dean]]>
Vermicomposting for various types of waste streams Tue, 14 Mar 2017 09:38:22 +0000
Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design) - by: BPopov http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20816 http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20816 I have no practical experiece yet with building aerated constructes wetlands. The inforamtion on the forum is here
forum.susana.org/component/kunena/36-con...gineered-wetlands-ew

I believe that one possibility is to aerate is through perforated pipes inserted directly in the substrate or have the the air supply from underneath the supporting structure like it done in industrial trickling filters. If we have the air cavity between the walls it would also help


Or it can be a cobination with the perforated pipes protruding through support layes vertically.
As far as I know pressurized air can be produced directly by windmils or hydropower pumps bypassing electricity.

I think in cold climate design active aeration could be a must since insulation also means restricted air flow from outside.
Regards
Bogdan]]>
Vermicomposting for various types of waste streams Sun, 12 Mar 2017 08:24:19 +0000
Re: Reply: Vermi-Trickling Filters for Sewage Treatment (looking for help to design) - by: goeco http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20815 http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20815
I believe a Chilean company has built a working vermifilter in Antarctica for processing sewage! The worms would only die if the reactor froze, so insulating this well is probably all that is required...

In my view small reactors should have sufficient ventilation without additional air supply (especially if there is an air cavity between the bottom/side walls and the media). However, once reactor volume increases to community or municipal scale I'd imagine it might be more difficult to provide sufficient oxygen passively into the core. What I like is how small scale one can go at low cost, so haven't really taken an interest in scaling up.

Yes, fans use very little electricity and would improve ventilation where air movement is insufficient. My experience has been that air pumps use more electricity to aerate water compared to using water pumps with cascading flow through porous media, but I'm not familiar with aerated constructed wetlands. Were you thinking of small diaphragm air pumps blowing air into the core of the reactor?

cheers
Dean]]>
Vermicomposting for various types of waste streams Sun, 12 Mar 2017 06:51:28 +0000
Re: Reply: Vermi-Trickling Filters for Sewage Treatment (looking for help to design) - by: BPopov http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20809 http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20809
Thank you very much for sharing very interesting info on vermifilters! It would be a challenge to build these in cold climate but believe this could be overcomed possibly utilizing the residual heat of wastewater and having the reactors insulated or installed within glasshouses.
I support your approach of using moderately pumps and other etechnical devices as soon as they low energy consuming
What do you think about enhancing air supply through the fans in the reactor lid or aerating the substrate actively with air pumps like it is done in aerarated constructed wetlands recently?

Best wishes
Bogdan]]>
Vermicomposting for various types of waste streams Fri, 10 Mar 2017 20:17:03 +0000
Re: Reply: Vermi-Trickling Filters for Sewage Treatment (looking for help to design) - by: goeco http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20692 http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20692 I see the vermifilter as the next step in the evolution of the trickling filter. It's still an aerobic packed bed reactor with a high specific surface area. By incorporating worms it becomes self maintaining - because the worms graze on the biofilm and convert this to humus, the microbial layer does not slough off and therefore a post treatment clarifier/sedimentation tank is not required to settle this as sludge. The humus itself improves the filtration because it increases the media surface area while remaining porous.

From my understanding of trickling filters, the dosing is to ensure a sufficiently aerobic environment is maintained on the media surface for optimum biofilm growth (air - water -air - water). From my experience at a domestic scale a rotating biological contactor or dosing system can be replaced by continuous tricking flow because the worms maintain an aerobic environment with good drainage, meaning oxygen dissolves into the wastewater as it trickles through the media, therefore not limiting microorganism growth. Would be interesting to see whether efficiency could be improved with dosing on a municipal scale, but in a passive domestic vermifilter system this would happen every time the toilet is flushed and in an active recirculating system the reactor capacity and flow rate are matched for greatest effectiveness and lowest cost.

cheers
Dean]]>
Vermicomposting for various types of waste streams Tue, 28 Feb 2017 21:44:16 +0000
Re: Reply: Vermi-Trickling Filters for Sewage Treatment (looking for help to design) - by: kevintayler http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20691 http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20691
I have just come across this thread. One question I have is what are the perceived advantages of a vermifilter over an old-fashioned trickling filter: The trickling filter is not a filter but a form of biological treatment - very simple and would seem to have a much shorter retention time than some of the technologies described in previous posts.

Trickling filters do need follow up secondary sedimentation but for small plants that could probably be done in a small pond. The other challenge is to get even distribution of wastewater across the filter surface - the traditional approach to this was to build circular beds with distributor arms driven by the pressure of the water emerging from them - but something simpler would be required for a small installation. The other point is that the flow should be discontinuous - this can be achieved with some form of dosing syphon. There was some interesting discussion on this on another thread on the forum.

Awaiting replies with interest
Kevin]]>
Vermicomposting for various types of waste streams Tue, 28 Feb 2017 21:03:26 +0000
Reply: Vermi-Trickling Filters for Sewage Treatment (looking for help to design) - by: AjitSeshadri http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20639 http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20639
Hydraulic Retention Time HRT in all phases of the treatment is important.

All together try to have minm. 8 to 10 days. Then the treatment works fine. Inlet BOD could be say 400-600 ppm and outlet would be less than 50 ppm.

Ensure to carry out regular operation & maintainance - O&M practices .This would call for efforts on manual labour. etc.

When it is completed then quantify sludge/ bio residues . And take them and co compost them with bio wastes or dairy sewage wastes.

All these make excellent manure.

With well wishes

Ajit Seshadri]]>
Vermicomposting for various types of waste streams Sun, 26 Feb 2017 08:17:55 +0000
Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design) - by: goeco http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20636 http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20636
I have built a series of prototypes over many years for my family-sized domestic wastewater treatment, with the intention of refining to be low cost and capable of producing effluent quality suitable for safe surface irrigation.

Most domestic vermifilters I hear of either use a septic tank followed by secondary treatment with the vermifilter, or alternatively they're just primary treatment vermifilters followed by disposal to subsurface effluent fields.

I've put the primary and secondary vermifilters in series. Because the primary treatment vermifilter is aerobic, the oxygen demand of the primary treated effluent is much less than with using a septic tank. It is also cheaper.

For secondary treatment I use a series of sedimentation drums, the purpose of these is to settle out residual suspended solids rather than filter these. This is because I believe that it is much easier to settle helminth ova out rather than try and remove with filters. Helminths being the key parasite to remove if using for irrigating food crops. Sedimentation tanks are very simple to build, with inflow going to near the bottom and outflow from near the top, in series.

My trickling vermifilter takes wastewater from the final settling tank and pumps this back through the secondary treatment vermifilter, which discharges to the first settling tank. Thus the settling tanks act as aerobic treatment reactors even though they are not ventilated to the external environment and oxygen. This is because of the large media surface area and trickling action of the secondary treatment vermifilter dissolving oxygen continuously into the wastewater.

My prototype domestic system recirculation pump is 3 watts which flows about 1 litre per minute at a 1.5 m head. The 1.5 m head gives me good depth of media in my vermifilter so I only have one pipe feeding the centre of the the vermifilter media surface. The water quickly spreads through the media as it travels downwards and the 15mm pipe is big enough to never clog. One litre per minute is 1.4 m2 per day cycling through the reactors.

The settling tanks therefore have both continuous (recirculation) and intermittent flow (when wastewater enters the system) with periods of quiescent operation resulting in good effluent clarity without having a filter to maintain.



One key advantage with the system is that I can easily pump sludge from the settling tanks back into the primary treatment vermifilter where this is rapidly converted into humus. Because so little sludge is generated this is rarely required.

The system is not designed to remove plant nutrients (NPK etc) because I want to retain these for fertigation. Provided pathogen removal is sufficient, I see value in the treated effluent. I don't like the idea of using plants within the treatment process, but prefer treating wastewater to then use on plants productively.

cheers
Dean]]>
Vermicomposting for various types of waste streams Sun, 26 Feb 2017 00:46:56 +0000
Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design) - by: guilherme http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20635 http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20635
I have some experience working with raw wastewater with vermifilter as a primary treatment, as well as small septic tanks as primary treatment and vermifilters as a secondary stage, always on gravity flow. Woodchips have been used as the filtration media. I never even considered recirculating, but I found it a very interesting idea indeed, where context allows.

Cheers!

Best from Brazil]]>
Vermicomposting for various types of waste streams Sat, 25 Feb 2017 20:49:01 +0000
Re: Vermi-Trickling Filters for Sewage Treatment (looking for help to design) - by: goeco http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20563 http://forum.susana.org/component/kunena/206-vermicomposting-for-various-types-of-waste-streams/20372-vermi-trickling-filters-for-sewage-treatment-looking-for-help-to-design?limit=12&start=12#20563
Thats amazing that India now require similar levels of BOD to New Zealand for surface application/discharge.

Indeed if using garden soil as your filtration medium you would need infiltration rates that can be maintained over time. One important factor to consider when using soil is that it needs to be at the right moisture content when packing the filter. Too dry and the clods don't break up sufficiently, too wet and you get what is called "lubrication" where you risk making mud. Once soil has become mud it is useless. High moisture content + movement = mud. Therefore the filter needs to be packed with really well broken up soil at exactly the right moisture content, and packed to exactly the right level of compaction, that is not too much to impede drainage but sufficient to ensure the soil doesn't move or further settle once wet.

I don't use soil at all, and consider it too unreliable over time. For passive systems (step filters) use sawdust. This will be cheap and available, but make sure that retention time never gets less than conservative loading rate. You'll need larger reactors than with an active (recirculating) systems.

I use bark or woodchips when recirculating because of higher loadings and lower retention times. In your case the outlet of the secondary module would recirculate through the vermifilter into the inlet of the secondary module, aerating the wastewater. That is, improved treatment also takes place in your secondary module (if it was previously anaerobic), not just the vermifilter.

Make sure that a layer of pervious cloth (shadecloth) is placed over the drainage layer before adding the sawdust.

The drainage layer (e.g. large gravel) requires some form of additional ventilation if scaling up width. Narrow and tall with side wall ventilation is great, but scaling capacity is most cost effectively achieved by wide reactors. These may require vertical pipes through the sawdust and set into the drainage layer, say one 100mm pipe per 3m2 of surface area.

cheers
Dean]]>
Vermicomposting for various types of waste streams Wed, 22 Feb 2017 20:39:03 +0000