Waste management, disposal and treatment has always been a major and reoccurring problem in the building and construction industry, especially in most areas in Lagos that's are always flooded or where the water table is very high. Septic tanks and soak-away pits tends to get filled up easily, which leads to frequent evacuation, thereby making it uneconomical..

The construction of biodegradable septic tank system is aimed at eliminating totally then need to evacuate waste (both solids and liquids)

The methods that would be employed in this process isn't new or recent , it's actually well in use in Ghana, Kenya and some areas in Cameroon, but it's just making its way to the Nigerian market ..

Ps.: I'm not a pro in the construction process yet, but just sharing my experience and little knowledge acquired in working with these guys

Schematic of the system

How's the class going?

Following

How it works

When organic material (including human feces, animal waste, and plants) is digested by microorganisms in the absence of oxygen (anaerobic digestion) a gas is released consisting of 60% methane and 40% carbon dioxide. This gas is typically called biogas and because it can be ignited, it may be used as a cooking and heating agent.

Various segment of the biodegradable system are:

1. The inspection chamber /inlet
2. Digester
3. Hydraulic pit
4. Septic tank/slurry pic

Work begins ... Our site is a 8 units 4 bedroom bedroom + attached bq at ikate - elegushi , lekki, Lagos state, built by yours truly

Excavation of digester (dome shaped)

Height: 1.8m
Radius: 1.8m

Building the digester dome

More on the digester wall

More

More ...

More pics of the construction process, building a dome is a very intricate and slow process

Using a dome shaped tank for the digester is informed by various reasons

1. The dome helps distributed the load on the tank easily to the Foundation, thereby making it as stable and strong as a concrete tank

2. The dome shaped tank help to trap the emitted gas better, thereby giving a higher yield (same reason the top of your gas tank has same dome shape)

The digester is constructed with clay bricks, as is stronger than your average blocks and is easier to shape into a dome shape , because of the size of each brick.

Also every mortar mixture is mix with a water proofing cement/against to ensure the tank is water tight ..

The tank is also plastered as the construction is ongoing, we have at least four layers of plaster at each level to ensure the digester is also air tight ..

Good'ay boss. I've been following this and subsequent threads keenly but no updates recently, hope everything's okay...

Happy new week

How’s the cost effectiveness? It seems it has an intricate process. Is it only recommended for high water table areas?

Thanks for always carrying us along.

EgunMogaji2:
How’s the cost effectiveness? It seems it has an intricate process. Is it only recommended for high water table areas?

Thanks for always carrying us along.

It’s still a relatively new system over here so it’s a bit expensive , but have seen some persons doing local adaptations of the same system which is way cheaper ..also did a little research and discovered they are really much more cheaper ways to have it done if you are making use of it for a single residence/personal usage ..


It can be used anywhere, not just where the water table is high..

Hi darenyx
Fantastic implementation of a tried and tested concept. Thanks for sharing your experience.
We did not see the completed dome and sewage system in operation. What has been your experience?
A few questions: How much gas does the system actually produce?
How did you size it for the apartment complex you built?
Will this system work with waste water (showers, car wash, industrial waste water etc)?
Do you have a cost for the system - you were silent on this?
Also do you have any local companies or artisans who specialise in constructing these systems that you can recommend?
Thanks for the post again.

innoventor:
Hi darenyx
Fantastic implementation of a tried and tested concept. Thanks for sharing your experience.
We did not see the completed dome and sewage system in operation. What has been your experience?
A few questions: How much gas does the system actually produce?
How did you size it for the apartment complex you built?
Will this system work with waste water (showers, car wash, industrial waste water etc)?
Do you have a cost for the system - you were silent on this?
Also do you have any local companies or artisans who specialise in constructing these systems that you can recommend?
Thanks for the post again.

Good day and sorry for replying late .. been very busy .. and for the completed images of the project, I couldn’t post them as I was robbed around that same period and lost my phones, hard drive and laptops

-the system has been in use for about 2 years now and we haven’t had any reason to evacuate or carry out any maintenance

The gas produced is enough to be used for domestic purpose for a family unit.. although in this case it’s not been utilized as most Nigerians aren’t comfortable cooking with gas generated from their waste

-the sizing is determined from the volume of waste that’s expected from each apartment .. in this case it was estimated that each apartment generated 2.5cu.m and we did the tank to accommodate 20cu.m since we have 8 apartments

-yes it would work for domestic and industrial use as long as non-biodegradable materials isn’t allowed to enter .. since the end produces are gas and water

-we actually did 2 of this for 2 separate projects sharing a boundary .. and it cost us about 8million in getting both he done

-I still have the contacts of the company that executed this, although is gaining more popularity now and should be less costly