I was wondering if anyone seen any information about using an Anaerobic Digester fed from the solid fish wastes and waste foliage of an Aquaponics operation to produce bio-gas.
Bio-gas output from aquaponic operations
(32 posts) (7 voices)-
Buffalochips
MemberPosted Sunday 30 Dec 2012 @ 9:03:42 pm from IP # -
Here is a basic biogas system combining human and animal waste that may help.
http://www.healthabitat.com/healthy-living-projects/nepal/removing-waste-safely/the-biogas-system
Posted Monday 31 Dec 2012 @ 6:36:19 am from IP # -
Jeffbloggs
MemberBuffalo
Interesting that you have these questions. I'm involved in biogas technology so I might be able to help.There are existing Biogas systems that are assosiated with aquaponics, but typically the assosiation is in reverse, ie the biogas waste is fed to the fish as nutrient/food. The biggest issue with using aquaponic waste would be the low COD (chemical oxygen demand) or "feedstock energy" of the mostly water aquaponic waste stream. A heavily diluted feedstock like aquaponic fish waste (unless you add the actual waste from fish processing ie fat&oils) will result in a negative energy balance for biogas production, as the heating requirement (for mesophilic digestion) will consume more than the methane energy being produced from the fish waste stream.
Essentially a waste stream analisys would be required to find out how much energy potential is still in the aquaponic waste stream. Digested materials always have very low energy ptotentials (is they've already been "biogased") and biogas systems will only achieve positive energy outputs if the energy balance calaculation include biogas system consumption. Hence typical biogas installations use waste streams from higher up in the feedstock chain, ie wastes that have not yet been digested. Any organic fat, oil or sugar (carbohydrate) is a potential energy source, so if you can collect these from fish processing there could be some development potential. Feel free to PM me should you wish to discuss further.
Regards
JBPosted Tuesday 1 Jan 2013 @ 7:14:33 am from IP # -
Buffalochips
MemberThanks for the explanation Jeff. I live in BC Canada and not only do we have fish plants but also cattle, pigs, chickens etc being raised within 5km of us. I do not doubt I can acquire enough materials to make a small system to heat/power my small operation with methane. Basically I was trying to decide on whether to divert my organic waste to vermiculture on try to put it into anaerobic digestion to produce methane. I thought if I combined the fish waste with the agricultural waste from the greenhouse operations I might be able to produce enough gas to operate a micro steam generator to create a little electricity and supply energy to a thermal heat-sink to help with heating in the winter.
Posted Tuesday 1 Jan 2013 @ 8:02:26 pm from IP # -
Jeffbloggs
MemberBuffalochips
Well that sounds a bit more promising. It's only possible to run Biogas with a good source of bacteria from digestion anyway ie cow/pig manure. So access to that is pretty important. With your fish waste do you know roughly how much is just water and how much organics? If it's less than 1% fish waste I'd say it's not worth it, over 5% will become more interesting but without actually doing a COD test will not be exact enough information to proceed down the biogas path. You could do a simple water evaporation test from a sample of fish waste to give you an idea if the waste is above 1%.How much waste do you produce from the greenhouse operations otherwise? That will probably be a much better feedstock. As I said before "undigested" material is much more potent. If you tell me what sort of energy load you have in heat/electrcity (in kWh/BTU etc) I can give you a quick estimation of system size and approx. cost for a DIY type system. My program will also give you required amounts of feedstock so that you can get a feel for it's viablility. BTW your idea of using biogas for heat is a good one and can be very cost effective.
Regards
JBPosted Wednesday 2 Jan 2013 @ 3:45:35 am from IP # -
Jeffbloggs
Memberlol Johno
It's a fishy business either way round...
Posted Wednesday 2 Jan 2013 @ 3:52:32 pm from IP # -
Buffalochips
MemberSo In other words,I have to wait till the tank is at normal output and then take the solids for testing.....gotcha
Posted Thursday 3 Jan 2013 @ 12:00:54 am from IP # -
Buffalochips
MemberOK...the verdict is Officially IN! Not only CAN you use aquaponic wastes for bio-gas but it turns out to be pretty dang efficient doing it. Found a Scientific study paper on a trial conducted. If anyone was interested here's the link http://journals.cambridge.org/download.php?file=%2FALR%2FALR11_04%2FS0990744098800144a.pdf&code=7f1d39f3516f72d93592b187924f0996
Posted Thursday 3 Jan 2013 @ 12:13:03 am from IP # -
Buffalochips
MemberOk linking wont work, google this phrase
Biogas production from solid wastes removed from fish farm effluents
you should see the paper from cambridge.org
Posted Thursday 3 Jan 2013 @ 12:16:52 am from IP # -
alfresco24
MemberInteresting questions.
I am not directly engaged in the recirculating aquaculture industry, however a good friend is intimately involved in designing and building freshwater fish farms in Australia, Asia, America's and Europe, and we've talked about energy use and byproducts at length.
Turns out that fish farms can be very very efficient in terms of converting feed to weight, almost 1:1.
The produced waste is very low when compared to stock such as chickens, pigs and cows e.g 18 times less per kg/lb of produced meat. Likewise the energy input and carbon footprint is very low compared to land stock.
That's not to say fish farms dont need lots of electricity, they do, to pump and heat the water, but it's quite efficient.
The down side is that farmed fish waste is very high in Ammonia, CO2 and to a lesser degree Nitrogen, with quite low bacteria content. The conventional way of removing solid waste is rotating micro sieve filters which are very effective. But the upshot is the volume of waste is actually quite low, only a few tens of kg per 10 cubic meter water tank per week.
This is not a lot of solid waste and it's not readily usable for methane production because it's low in nutrients. To be made usable it needs to have the ammonia removed - drying - and then combined with other nutrient waste.
I haven't done calculations but experience tells me the harvest-able methane would be a tiny proportion of the energy required to run a recirculating aquaculture farm, and the capital and operational investment required is just not worth while for the business. Perhaps a home or other small business associated with or co-located to fish farms might be able to get an economical return of methane or ethane, but I suspect it's something you'd do to be super-green rather than economically replace grid supplied or Solar PV electricity.Posted Thursday 3 Jan 2013 @ 1:37:52 am from IP # -
Jeffbloggs
MemberBuffalochips
I never said it's not possible, nor unfeasible, however how much energy you can produce from AD depends purely on the energy potential of your aquaponic waste, if it is low you will need another source. Low COD simply means low energy output for most feedstocks, so getting good feedstocks is key for operation. Remember digestion has a heat load in the requirement to operate in the mesophilc range (ie to heat the feedstock to 37'C for digestion), and it is critical that this energy amount is balanced in your calculations of what is left over and useable for external consumption.Particularly in smaller installations like you PM'd me AD is sensitive to temperature and feedstock fluctuations, that will see a reduction in system performance if not managed properly. So it would be good to source a reliable feedstock before committing to installing biogas. Fat and oils will digest into nearly their weight equivalences of petrol or diesel, so a small volume of this type of feedstock will outperform any mostly water aquaponic feedstock by far, and offer some redundancy.
But if you do use biogas you also don't need any batteries for energy storage, storing the biogas is easier and far cheaper than storing energy in batteries, and a simple gas modified petrol of diesel 5kW generator will produce all the on-demand and baseload power and heat you need. Waste heat can be extracted from either the engine water jacket (if it's a water cooled geny) or by a simple $150 gas/liquid heat exchanger on the exhaust system. You can expect around 2-4kWh of electrcity (plus about the same in heat) for every m3 of biogas stored that will only cost you some EPDM pond liner $15m2 (most biogas plant use EPDM covers for biogas storage). In comparison a useable 1kWh of batteries will cost around $500.
I'd also recommend doing a energy audit of your consumption first to see how you can reduce it, and then you only have to produce what is left. That way you might find that buying a new fridge or freezer will be cheaper than installing any over dimensioned generation and then wasting energy instead.
Regards
JBPosted Thursday 3 Jan 2013 @ 4:45:10 am from IP # -
Buffalochips
MemberThanks JB, Very helpful
So here's the golden question. How much biomass would it take to create 40m3 of bio-gas and how much should be animal and how much can be vegetable? Restaurants already divert they're waste here to biomass but they receive nothing for it other than reduced waste disposal fee's. I believe if I were to offer them a small discount on the organic produce/fish prices I would be able to easily divert a lot of that waste to my facility, especially since I could pick up that waste when making our daily deliveries. To Alfresco24
That's the beauty of aquaponics. the ammonia etc that is toxic to the fish is converted into nitrates by naturally occurring microbes that the plants absorb and the water is cleaned and returned to the fish to "load" up again. A complete bio-system where you preserve 95-98% of your water and produce ABUNDANT crops with a sideline of fish production. I wasn't looking at it as a money making bio-gas operation but as a self sufficiency project.
Posted Friday 4 Jan 2013 @ 12:05:48 am from IP # -
Jeffbloggs
MemberBuffalochips
The level of ammonia needs to stay within reason depending on your feedstock sources and concentration otherwise the AD biology might "tip over" aka go acidic and kill of the methane forming bacteria. But yes AD can handle some ammonia.For energy outputs of different substrates you can find them here:
http://www.biogas-info.co.uk/index.php/biogas-yields.htmlPosted Friday 4 Jan 2013 @ 3:55:09 pm from IP # -
alfresco24
MemberBuff..
The amount of waste water created in a well designed and operated aquaculture system is less than 2%
This based on systems that include several stages of filtering, cleansing and oxygenation. Even evaporation is not a significant loss vector when fully enclosed buildings are involved. It can be very close to a closed loop system.
Starting from scratch today you can build a fully looped system that can produce 50,000kg-100,000kg a year for $2m-$3m depending on location, with the only major expenses being fingerling stock, feed, electricity and labor, with almost zero waste and emissions. The payback time is often in the range of 2-3 years.
I regret I am not familiar with any biomass-biogas installations but I don't think I'm wrong in believing that even biomass systems create some amount of disposable waste that cannot simply be dumped back into the ecosystem without further treatment or conversion.
Do we have anyone here who has been involved in the construction or operation of a working scale biomass generator?, and can quote figures for inputs and outputs?
BTW I'm talking about Aquaculture producing fish products, not hydroponics (aquaponics) producing vegies and herbs.Posted Saturday 5 Jan 2013 @ 4:38:20 am from IP # -
Jeffbloggs
MemberAlfresco
The wastes from AD from purely organic feed stocks generally do not require further treatment before reuse in agriculture etc. In fact most sewage is treated in AD systems as the final stage of treatment before being irrigated. Obviously if the organic feed stock is contaminated ie heavy metals, most of this will come back out of the system, and could be more concentrated when de-watered. Depending on the bacteria cultures used even some of these wastes can be converted into less harmful/concetrated waste.
All biogas generators are either off the shelf natural gas (the methane is the same as from the pipe) or gas converted petrol/diesel generators that can then run off methane. There's literally millions of AD plants already in operation worldwide.
On Aquaponics: this is NOT hydroponics. It's a hybrid fish/plant setup.
Posted Saturday 5 Jan 2013 @ 5:36:05 am from IP # -
alfresco24
MemberJB
Using your 1.4MW plant as an example, what is the input and exported waste mass/volume per week and the harvested methane in the same period? where does the waste go and what is it used for?
(When you say 1.4MW do you mean gas energy equivalent calorific value or applied work/electricity generated?)I've seen a few mixed use aquaculture/hydroponic farms in Asia (don't believe there are any long run commercially sustainable ones in OZ) and have seen data that the fish out of those farms have a poor feed/mass take up ratio (typically under 80% or less) and the fish are less healthy (higher mortality) don't taste as good, and as a result don't get good prices.
I have nothing against people going down that path for the sake of a hobby or small scale commercial 'hobby farm' - good luck to them.
In Adelaide most people are aware (or maybe not) that virtually all the sewage treated at the Bolivar plant (60% of greater Adelaide sewage) is sold to the adjacent market gardens for irrigation. What could be better!Posted Saturday 5 Jan 2013 @ 6:02:56 am from IP # -
Jeffbloggs
MemberInput streams vary over seasons, the methane content varies accordingly.
For example about 20 tonnes of bakery waste, 30 tons of liquid dairy waste and 30 tons of whey waste to produce about 16,000m3 of biogas (10,000m3 of methane) that produces about 32MWh a day of electricity and about 50MWh of heat that can be used onsite for the Biogas plant heating etc. Most of the electricity is however exported (typically biogas systems consume less than 1%) but have tons of heat left over.Posted Saturday 5 Jan 2013 @ 8:21:23 am from IP # -
An Australian version of interest.
Posted Saturday 5 Jan 2013 @ 8:41:08 am from IP # -
Buffalochips
MemberHi JB and thanks for the input. Sounds like you have a very large scale methane production system, however, what I was proposing is a small scale system that could provide enough gas to produce steam for energy/heat on a small commercial (3000-10000 sq ft) green house aquaponics system. I want to use the fish/agriculture/algae waste from the greenhouse. If need be it would be easy to add an algae production area to the system thus increasing the viability of methane production and providing oxygen for the aquaponics system as well. Algae is very efficient at removing CO2 and producing O2 I am told, as well as being a high source of methane in its natural structure. By skimming off the algae we remove the problem from the grow beds and if feasible use it in the anaerobic digestion process to solve our energy problems that plague commercial AP systems.
Posted Saturday 5 Jan 2013 @ 5:55:43 pm from IP # -
Jeffbloggs
MemberBuffalochips
I posted a link to a website above that shows biogas outputs for various waste streams, the post about biogas was in response to Alfrescos questions, and were not meant to motivate you to build one of the same scale!! Even though you'd probably want to! Algae is a viable alternative. Nothing's "too" green for biogas!
Regards
JBPosted Sunday 6 Jan 2013 @ 3:08:33 pm from IP # -
Keef-Wivanef
BlockedThese guys are involved in some fishy business.
http://www.holophasec.com/index.php/about-usbriour-teami/corporate-profile
They are generating heaps of methane.Posted Sunday 6 Jan 2013 @ 3:24:50 pm from IP # -
Buffalochips
MemberHey JB, When you told me the amount of feedstock involved etc at your plant I did a bunch of rough math to get it down to a scale that I figured might work for me. You (and others) were correct in asserting you cant do it on the greens/fish waste. However the addition of a harvest-able Algae crop, which is a very good source, seems on paper to look like it may be viable. I am going to try (no harm in trying) to make a small scale bio digester and study to see how much I can produce from the waste/algae sources. Even if its only enough production to keep my water above 15C in my gardens insulated tanks I will be happy. Every Watt saved will help. As to heating the digester itself I was thinking of burying it in compost which should keep it warm enough over the winter to enable the anaerobic process. I was thinking of using a heavy duty 100gal rubbermaid livestock watering trough for the body and an EPDM liner sealed over the top of it. Any input appreciated JB
Posted Sunday 6 Jan 2013 @ 4:15:11 pm from IP # -
Jeffbloggs
MemberBuffalochips
Personally I have not built a "small scale" one yet. But they are very common (millions) in India and China (youtube/google for ideas). They have the most cost effective solutions if materials are expensive but labor cheap. In western nations it's generally materials cheap, labor not, so accordingly a different solution is required.Here's a video showing a version of how it can be done small scale.
You can also just start with one heated & insulated 44gallon plastic drum with an external plastic bag for methane capture. The two most important things is 1. do it outside in well ventilated area to avoid hazardous gas build up and two don't use any metals (apart from 316 SS), use plastic/PVC etc instead for plumbing etc. to avoid corrosion and leaks. Also don't use a high pressure (read strong bag) storage, as this can lead to over pressure in the rest of the system and potentially dangerous failure.
It is critical to keep temperature in the system stable so don't underestimate it. It's based on a cow stomach, which is a warm blooded creature that maintains temperature within 1'C. Performance wise you're better off having a smaller volume with good temperature stability than having a larger volume with no temperature stability, especially so for winter.
Burying it in compost is an idea, but messy and unnecessary. You're better off insulating the AD container well and using a old HWS to burn the gas and heat it. You could even use an old large volume Natural gas HWS boiler, it's already insulated and has the burner underneath to keep it warm...just make sure it can't build up pressure EVER though, otherwise it will go up mythbuster style! Also preheat feedstocks if possible to operating temperature to avoid shocks to the system.
With any gas heater run by methane, due to the low but persistant H2S content non stainless combusters and heat exchangers will corrode (especially copper ones!). For biogas pre-consumption processing a combination of de-humidifing or condensing the biogas (biogas pipe underground over a length will suffice to cool/condense) and sacrificial steel wool filter in a a PVC/ceramic container will reduce H2S to a more usable level. 316 Stainless steel (not 304!) everything would be best to avoid pre-processing but is expensive and not so common.
It's a bit hard to post construction recommendations without knowing your local resources etc. but feel free to post a rough design here for recommendations. This is the part where local ingenuity comes into play! Start small and everything should fall into place with experience..it's the best and safest way to learn!
Good luck and always put safety first.Regards
JBPosted Monday 7 Jan 2013 @ 5:11:04 am from IP # -
Buffalochips
MemberOK I understand all the boiler requirements no problem. I hold a cert in Refrigeration and small Boilers but have been out of the Ind. for quite some time. I had already designed the system to be atmospherically vented. I have a friend in the propane business and he's looking for a functional flare off device for me. If I took a ordinary stainless vessel(304) and had a machine shop fashion an outer bottom shell of 316 would that suffice? I had already seen plans for a scrubber and included those but thanks for the clarification. Im on a disability pension at present so buying a boiler isn't in the cards. The volume of water in the boiler/exchanger only needs to about 25 gal I figure as I will only be maintaining 100 gal roughly at 17C and they will be well insulated. Having a second loop with a flow regulator to control heat to the AD should be no problem. I did a lil more research earlier and found an Algae with a C/N factor of 2-2.5 They were saying when they added this strain to their bio-stock it Doubled methane production. Unfortunately I wasn't at hope but I will try and find it and send you a link. One other thing I wanted to ask. Does your plant used CO2 sequestering? I was thinking down the line of finding a way to take the cooled exhaust to feed CO2 to the algae growth for cleaning and help algal growth.
Regards
BuffPosted Monday 7 Jan 2013 @ 11:22:25 pm from IP # -
Buffalochips
MemberFound the study JB, here's the link
https://wiki.umn.edu/pub/CapstoneAlgae/WebHome/Algal_Sludge_digestion!.pdf
ttfn
Posted Monday 7 Jan 2013 @ 11:58:43 pm from IP # -
Jeffbloggs
MemberBuff
Thanks for the link. With the boiler and mixing/matching 304/316: Are you planning on using it as a HWS boiler or as the AD digester like I suggested? As a bioler your idea should work, as a digester it obviously won't because you need the whole thing to be 316, especially there where the liquid meets the gas.The algae you linked to looks interesting. Running it with other feedstocks will require testing, there's no two feedstock mixes the same. If you change the feedstock do it gradually over a few days to allow for the bacteria cultures to adapt.
We currently don't reuses the CO2 we produce. It's in the future plans though when we upgrade our 20year old hydroponic greenhouses.
Posted Tuesday 8 Jan 2013 @ 2:15:54 am from IP # -
Buffalochips
MemberI can only imagine what your chemical costs are for the hydroponics these days (if you still use them that is). Aquaponics is definitely cheaper and less labor intensive than HP. I grew HP about 15 years ago and In comparison?, there is no comparison! the vegetables taste a LOT better, water balance is easier. The only thing you need to add is iron and adjust your ph every now and then. Anyways the algae in question they used co-digested with paper as feed stock. Would there not be more energy in actual vegetable wastes? IE. tomato of cucumber vines etc? I know there isn't much in the leafy greens like lettuce, chard, celery. Myself I don't care about the whole Bio-diesel thing as my truck is already converted to a HHO hybrid system. It's on 08 Dodge 2500HD with the 5.7l Hemi and its getting about 24mpg city and about 45 on the highway (32 when towing).
It seems like the whole bio-fuels from algae industry is concentrating on the bio-diesel aspect but very little is being done on the methane side of things. Probably because with bio-diesel here they are still 70-80% Petroleum based which allows the BIG oil co's to still have their hefty profits so its not a threat to them.
As to the AD I know it has to be all plastics due to the ammonia's and acids. I was speaking about the HWS being a stainless bottom. Is it as crucial if you are scrubbing the gas first?Posted Tuesday 8 Jan 2013 @ 3:08:41 pm from IP # -
Keef-Wivanef
BlockedHi Jeff
I'm not far from Perth.
Can I come and have a tour of your biogas plant?
I'm thinking of setting up a large one because I have a huge supply of feed-stock.
Looking forward to meeting up and inspecting your 1.2 MW plant.
Best wishes
KeefPosted Wednesday 9 Jan 2013 @ 8:13:25 am from IP #
