Biodigesters for Human waste water

The biodigester is a septic tank / alternate septic tanks that make it eco-friendly, low maintenance (to no maintenance) and cost-effective.

These septic tanks are infused with bacteria inoculum. The Anaerobic Microbial Inoculum is supplied in 200 ltr Barrels.

The septic tank itself can be made of FRP or readymade septic tanks. These tanks usually have 3-4 chambers; thereby, the inoculum has a maximum surface area on the tank to act on the sludge. The inoculum eats the sludge away, and the treated water exits the pipe's outlet.

The FRP tanks are strong enough to hold soil pressure but not vehicle movement. In many cases, we build an encasement to the FRP tank and a concrete slab to protect the tank from being dug or broken with axes in the lawns or driveways.

Inspection chambers are required on both ends, which may require maintenance in cases of blockages. We have never had to remove the sludge from the septic tanks at any of our sites (using since 2017).

The Defence Research and Development Organisation (DRDO) developed a specialized bacteria inoculum for use in biodigesters. This technology primarily addresses the issue of managing human waste in high-altitude cold regions, such as those found in the Himalayas, where traditional waste management systems are ineffective due to low temperatures.

The water that comes out from the outlet has a pathogen-free efflux. The effluent water can be used for gardening or put directly into a bed of suitable plants (like canna lily or bamboo) or further treated using a reed bed to store the water that gets drained out for domestic use. We at Vitrag prefer to let the water out into a soaking pit.

The byproduct of this process is biogas, which can be piped out through a vent and stored for cooking. In our case, we just let the gas flow out through a gas vent, as LPG is much easier to manage.

A common complaint is that the biodigester emits a vague smell while initiating a new tank. Thus, we recommend placing an inspection chamber with a gas vent before the biodigester inlet.

We have used biodigesters for residences and workers' toilets, while the technology is used for large gated communities in Coimbatore.

It is recommended to top up these tanks with inoculum every few years once in case the house toilets are used sparingly. For homes used regularly, we have observed that they run without any maintenance as the inoculum feeds and regenerates or grows with the increased feed.