Decentralized sanitation a way to go for Ukraine?

  • BPopov
  • BPopov's Avatar
    Topic Author
  • Ecologist involved with ecosanitation in Ukrainian Carpathians
  • Posts: 122
  • Karma: 6
  • Likes received: 39

Re: Decentralized sanitation a way to go for Ukraine?

goeco wrote:

Bogdan describes a highly risky approach to fertilising crops, using sludge from septic tanks and pit latrines. This will contain pathogens and will result in disease.


Hi Dean! Thanks for the input!

That's right-- this approach is highly risky but it is here and it might make sense to shape into safe onewhile leaving the pattern of direct linking the households with small farm without intermediate WWTP. If vermidigester can replace the septic that would be great breakthrough, but I am still not convinced that it will be so easy in cold climate. It takes quite an effort to keep vermidigester above 10 degrees, while septic is basically hole in the ground.
Regards,
Bogdan

Bogdan Popov
The Ecosolutions Forge
www.ecoforge.org
You need to login to reply
  • bowenarrow
  • bowenarrow's Avatar
  • Posts: 30
  • Likes received: 6

Re: Decentralized sanitation a way to go for Ukraine?

All the more reasons to remove the transporter of pathogens- urine. Whilst urine is almost a sterile product ( and useful in its own right) it makes faeces difficult to handle and the volume increase a real problem. Leaching of mixed urine and faeces into waterways is criminal.
Ross
You need to login to reply
  • Decentral
  • Decentral's Avatar
  • Independent consultant with special interest in decentralized wastewater systems
  • Posts: 17
  • Likes received: 4

Re: Decentralized sanitation a way to go for Ukraine?

Dear all,

I enter this discussion at a later stage and in general I agree with the first comment of Philippe. Decentralized wastewater systems are a common case in many small population centres and villages in Europe, especially on-site sanitation. However, such solutions are a real problem in areas with high water table or very small plots. Therefore, the choice of appropriate level of decentralization is question of technical and economic analysis, which normally can not be done by the community itself but should be delegated to professionals. Some general points related to decentralized systems can be found at the site Decentralized wastewater systems

The reuse of treated water is a viable alternative in arid and warm climates, but in Europe it is possible for a few months in a year, so is a problem as well, which needs to be considered. You are aware that the water quality requirements for irrigation purposes and for discharge are different, the last are much more stringent.

I am in full support for decentralized solutions but we have to be careful in the choice of the most appropriate one.

Best regards,
Roumiana
The following user(s) like this post: BPopov
You need to login to reply
  • BPopov
  • BPopov's Avatar
    Topic Author
  • Ecologist involved with ecosanitation in Ukrainian Carpathians
  • Posts: 122
  • Karma: 6
  • Likes received: 39

Re: Decentralized sanitation a way to go for Ukraine?

Decentral wrote: The reuse of treated water is a viable alternative in arid and warm climates, but in Europe it is possible for a few months in a year, so is a problem as well, which needs to be considered. You are aware that the water quality requirements for irrigation purposes and for discharge are different, the last are much more stringent.


Dear Roumiana!

Thank you for useful links and comments !

This is very important note that irrigation water needed only for few month in cold climate while waste water is produced all year round. We need either a fllexible system that allows changing quality of efflluent or constantly treat it to discharge quality while transfering the nutrients into solid form for storage and later use. Looks like vermifiltration offers this later option. Is it correct Dean?
Regards,
Bogdan

Bogdan Popov
The Ecosolutions Forge
www.ecoforge.org
You need to login to reply
  • phreymon
  • phreymon's Avatar
  • Posts: 24
  • Karma: 3
  • Likes received: 12

Re: Decentralized sanitation a way to go for Ukraine?

Dear Bogdan, dear Dean,

I would prefer simplified sewer systems not because of costs, but because they are in my view less vulnerable than solid-free sewer systems. Indeed, with the latter, you have to rely on compliance and good behaviour from all the users. If one household does not maintain properly his septic tank/interceptor, or if the design is not good, then quickly clogging issue will appear. Same thing if stormwater enters the system.

Bogdan, it is a good point to mention frost. I think that the problem is the same with both type of sewer systems. Regarding pumps, it will depend on the level of decentralisation you are targeting. Simplified sewer systems may be used at street or neighbourhood level. Bigger than that, we fall into conventional again.

As for vermidigesters in every household, how realistic is that? In theory, it sounds good. But worms are sensitive beings. Besides, they will not treat all the wastewater. How to best to use this emerging technology? And at which level of decentralisation?

Cheers,

Philippe Reymond
You need to login to reply
  • goeco
  • goeco's Avatar
  • Self employed innovator with an interest in wastewater treatment systems and recycling of nutrients
  • Posts: 206
  • Karma: 8
  • Likes received: 110

Re: Decentralized sanitation a way to go for Ukraine?

Bogdan, no... vermifiltration retains the nutrients mostly in liquid form. In contrast to other treatment systems most of the nitrogen is retained, so is a good option where immediate irrigation to vegetation is viable. What happens when your septic tanks freeze? Do the underground soakage fields also freeze? How deep under the ground must you go for reliable soakage that never freezes? Is the water table always high when it gets cold?

I'm guessing swampy ground is the exception for communities of people in most parts of the world. Certainly communities living on top of high water tables have "special needs" in terms of wastewater management, but in most other cases dwellings should have sufficient land available on which to surface discharge with secondary treated wastewater. Surface discharge has huge advantages, but does require secondary treatment and of course the surface can freeze. No doubt Ukraine conditions would preclude surface discharge for some (how much?) of the year and I'm most interested in solutions allowing treated wastewater discharge to ground.

What seems to be the general assumption in the sanitation community is that secondary treatment is outside the means of people in developing countries, where not able to access a sewer. Septic tanks are the cost limit, as far as they are willing to go.... apparently without properly designed leach fields in many cases. Addressing one problem with another (very ugly) problem, FSM. Yet domestic scale vermifiltration systems with secondary treatment can be constructed at lower cost than a septic tank, so can be "decentralised" to the household level, provided vegetation is available to irrigate to.

Phillipe, worms are very robust beings, but like any living organism require conditions within their limits, especially with regard to temperature. Freezing them or cooking them is death, although the eggs survive. This just means the digester needs to be insulated in cold climates and given shade in hot sunny climates.

I agree with you that septic tanks are an unreliable interceptor for small-pipe simplified sewers. This is because ignoring the buildup of sediment/solids doesn't directly affect the user, their toilet still flushes. However, importantly, primary vermifilters by design no longer function once full. The toilet no longer flushes away because the inlet to the vermifilter eventually becomes blocked with the growing pile of solids. This makes them eminently suitable for solid-free small-pipe (low cost) simplified sewers. Of course only twin chamber designs should be endorsed, so once full (maybe 6 years depending on capacity) the inlet is simply switched to the other chamber.

A simplified sewer without solids is much lower cost because the pipe size can be dramatically reduced, so would be suitable for peri-urban areas with no available land and those with high water tables.

cheers
Dean

Dean Satchell, M For. Sc.
Go-Eco Sustainable Solutions
www.go-eco.co.nz
You need to login to reply
  • BPopov
  • BPopov's Avatar
    Topic Author
  • Ecologist involved with ecosanitation in Ukrainian Carpathians
  • Posts: 122
  • Karma: 6
  • Likes received: 39

Re: Decentralized sanitation a way to go for Ukraine?

Thanks Dean!
Ukraine is a huge country with highly variable climate and other condtions. High ground water level is very common in many places both for natural and anthropogenic reasons. The water table gets highest level usually in spring after snow melt and in autumn after rains. In some places it drops down a in the middle of the winter , in some places it stays. Very often the water table disappears completely after midsummer and that what makes the wells go dry and people complaining about the water shortages. The frost line depth varies between 50 cm to 1 m although lately due to (probably) climate change the winters become milder ( last December hit the warmest temperature record) and thus frost line is usually higher. Common practise is to have 50 cm of dirt over both septic tank and top of leach trench and mostly it is enough to keep things unfrozen. Sometimes during very cold winters on North of the country infrastructure may freeze on this depth and in such localities pipes and tanks usually buried deeper.
What is noticeable that in places of high ground water one can expect more attempts from people to treat their waste water with septic tanks since it directly affects their and neighbors well water.
Usually in the country the size of plots that belong to dwellings is between 1 000 and 3000 square meters. Most of these plots grow fruit trees , shrubs and vegetables and it is possible to use the secondary treated effluent produced on site for irrigation for 2-3 month during the year. It is what many people already do with the grey water and some of them can even do this with the black water from their septics. However during rainy summers (like the last one) irrigation might not be needed at all.
I can’t argue with the possibility to have a vermidigester at each household for primary treatment before I see robust, low cost, low maintenance, cold climate working example of one
One of the limitations for this technology I would see that most already built houses have the outlet for the waste water underground and vermidigester is probably better to build on surface? This would involve sump and fecal pump (not good at all). Underground vermidigester could be an option? But then we could possible consider modifying septic tanks into vermidigesters? That would be an interesting project!
Still for me the key factor which would makes local closed loop sanitation work is a viable profit generating LOCAL FARM. Not worms, urine separation or pipes, but people having meaningful job where they live, producing good stuff for the other people and not depending on the state to solve their problems.
Best,
Bogdan

Bogdan Popov
The Ecosolutions Forge
www.ecoforge.org
The following user(s) like this post: goeco
You need to login to reply
  • phreymon
  • phreymon's Avatar
  • Posts: 24
  • Karma: 3
  • Likes received: 12

Re: Decentralized sanitation a way to go for Ukraine?

Hi Dean,

You make me (us) very curious about the potential of vermifilters. I have the following questions: (i) it is just a filter: how does it deal with 100 L wastewater per person per day? And how can the pathogens and nutrients be retained?; (ii) what do you do with the effluent? In my understanding, the pathogen removal is rather low; (iii) I think that worm management is more that temperature impact on individuals: the colony has to grow, and be efficient. I see as further risks a two high water-content (or even saturation in case of clogging) and sometimes potentially high nitrogen content.

It would be great if you could send us a drawing of what you exactly have in mind, mentioning the scale of operation.

Cheers,

Philippe
The following user(s) like this post: BPopov
You need to login to reply
  • goeco
  • goeco's Avatar
  • Self employed innovator with an interest in wastewater treatment systems and recycling of nutrients
  • Posts: 206
  • Karma: 8
  • Likes received: 110

Re: Decentralized sanitation a way to go for Ukraine?

Hi Bogdan, yes, with vermifiltration the outlet is lower than the inlet, i.e. the depth of the media lower. Septic tanks have the outlet at the same height as the inlet, which appears to be set just under the height of the frost line... all one level right through into the leach trench.

The only reason the vermidigester would be built on the surface is that a failsafe overflow can be built in to ensure the water table does not rise and flood the digester. If underground, the sump under the digester can have a float-switch operated pump because the solids are removed, but this would need to be reliable. If it fails, the water table will rise in the vermidigester and drown the worms... unless the leach trench were always above the water table.

To me it's not so much about when irrigation is needed, but when irrigation is not limited by freezing temperatures. Surface discharge removes the risk of groundwater contamination, so I'm wondering how many months a year surface irrigation is possible? How many days in a row can occur where the temperature never gets above freezing?

cheers
Dean

Dean Satchell, M For. Sc.
Go-Eco Sustainable Solutions
www.go-eco.co.nz
You need to login to reply
  • goeco
  • goeco's Avatar
  • Self employed innovator with an interest in wastewater treatment systems and recycling of nutrients
  • Posts: 206
  • Karma: 8
  • Likes received: 110

Re: Decentralized sanitation a way to go for Ukraine?

Hi Phillipe,

I am building domestic scale vermifilters out of low cost recycled materials, with developing countries in mind that most need the technology. The primary vermifilter uses 2x large plastic fruit crates and secondary filters use 2 x plastic 40 gallon (200 litre) drums.


1200 x 1000 x 800 forklift style fruit crate


Twin chamber domestic primary vermifilter

There is no doubt in my mind that secondary treatment could be cost-efficiently scaled to the community level for irrigating a local farm, with primary vermifilters at the household and small diameter pipes to a community facility for secondary/tertiary vermifiltration.

In its simplest form a vermifilter is a drum filled with media such as sawdust, bark or even biochar, with an inlet at the top and an outlet at the bottom. The inflow volume depends on capacity and residence time, which depends on the porosity of the media and media depth. Biofilm develops on the media and the worms graze that biofilm. By passing wastewater through the media with its very large surface area, rapid aerobic treatment takes place, removing BOD and pathogens. Because the worms work the media, porosity is maintained. The key is maintaining an aerobic media, which means ventilation.

Its easy to provide conditions for worms to thrive, the media just needs to drain and ventilation is essential. The worm population quickly adjusts to different quantities of influent and nitrogen is only an issue if no flush water is used. Low flush works fine.

Matching media volume and porosity with the volume of inflow is important in "traditional" vermifiltration. The longer the retention time, the greater the level of treatment but with an increased risk of inflow exceeding outflow. The simplest system uses gravity alone but requires slope away from the dwelling. Variable dosage (increased loadings from bath or washing machine etc.) is allowed for by having sufficient capacity.



My preference is for a relatively coarse media and constant recirculation. I use horizontal flow reactors and a modular design that has the reactors in series with number of reactors determined by number of users.


Secondary recirculation vermifiltration reactors in series

Recirculation is with 5 watt 12 volt pumps and a small solar panel. The total cost of each reactor is about US$80

No need for anaerobic filters or planted gravel filters or polishing ponds as required in DEWATS

N is retained in the wastewater because treatment is fast and aerobic. Anaerobic digestion offers conditions suitable for ammonification and loss of nitrogen to the air. There is plenty of research showing high destruction levels of bacterial/viral pathogens, whereas helminths are retained in the filter medium so are removed from the wastewater.

cheers
Dean

Dean Satchell, M For. Sc.
Go-Eco Sustainable Solutions
www.go-eco.co.nz
Attachments:
The following user(s) like this post: phreymon, BPopov
You need to login to reply
  • BPopov
  • BPopov's Avatar
    Topic Author
  • Ecologist involved with ecosanitation in Ukrainian Carpathians
  • Posts: 122
  • Karma: 6
  • Likes received: 39

Re: Decentralized sanitation a way to go for Ukraine?

Hi Dean!
Most of Ukriane can expect 8 month above zero temperatures. Theoretically during this period surface discharge is possible and it can be extended for at least two more month if discharge would go under some insulating mulch layer further enhanced by snow layer on top. The infiltration would depend on soil type (sand or clay), how saturated it is from the rain and humus (organic) content. Some plants will benefit constant wetting with nutrient rich liquid and keep nutrients uptake (willow) for most of the time. Some simply tolerate it and uptake nutrients for limited period during warm season or at certain accumulated degree day while at other time let it all pass through soil or accumulate in it (quince, raspberries). Planting on ridges with discharge in between them into mulch filled depressions would be nice self-regulating approach.
A good strategy will be buffering the soil with biochar or zeolite that will absorb unused nutrients (and water) and later release it to the plants during active vegetation phase on demand. A lot of things would depend on mycorrhiza forming fungi that bond the nutrients and enhance their availability to plants. They play enormous role in cold climate soil nutrient cycles.
Another approach is glass –house growing when irrigation can be kept all-year round given artificial light and heat is provided.
Anyway it is quite possible to design surface discharge system for the most part of the year in Ukrainian climate.
Best,

Bogdan

Bogdan Popov
The Ecosolutions Forge
www.ecoforge.org
The following user(s) like this post: goeco
You need to login to reply
  • Decentral
  • Decentral's Avatar
  • Independent consultant with special interest in decentralized wastewater systems
  • Posts: 17
  • Likes received: 4

Re: Decentralized sanitation a way to go for Ukraine?

Dear Bogdan,

you have initiated a very interesting discussion and I would like to thank you.

Regarding the size of the plots you have mentioned - it looks that on-site individual solutions will be more economically viable, compared to a centralized sewer, which collects settled wastewater after the septic tanks, because of the length of pipes which will be required to transport it to a wastewater treatment plant.

The issue of water reuse - we have to think of the wastewater system and the reuse system as a whole. In other words, we can reuse as much as we produce. And here comes the issue of inhabitants - how many of them are producing wastewater and how much of it. Are they full time residents or just visiting in summer? The quantity of wastewater produced is directly related to the availability of central water supply. If people are using wells in their own plot, then the consumption might be lower. This information is essential in order to plan your farm. Also, if people reuse gray water directly, this will reduce the amount of black water by ~50% and you may end up with no water for your plants. Considering these points, I would encourage on-site solutions.

The vermifilters suggested by Dean look as an interesting idea, but before you can apply it, a serious amount of research would be needed, in order to be successful in your case.

My impression is that you would not like to relay on local authorities, but the issue of regulations is very important. At the end of the day we would like to implement a system, which is legal :-) and applicable to numerous cases, not just in your own property.

I like your ideas for the reuse of treated wastewater - could you provide information regarding the water requirements of willows?

Best regards,

Roumiana
You need to login to reply
Share this thread:
Recently active users. Who else has been active?
Time to create page: 2.326 seconds