Zimbabwe: Beitbridge Town Council – Earthworm waste water treatment and recycling

The Earthworms Waste Water Treatment and Recycling a low energy and low cost waste water / sewage treatment technology using earthworms. The project was done in Beitbridge Town Council’s Ward 4 where 9 houses that were situated below the existing trunk sewer line could not be connected to the system since 1998.The technology was for treating waste water (containing human waste and food left overs) at source using earthworms. The system cleaned, detoxified, disinfected and neutralized the waste water from the kitchen, laundry, bath and flush toilet. The technology produced clean detoxified water, not potable but could be used to flush toilets, in agriculture or if discharged into rivers would reduce water treatment costs. The earthworms devoured on all the pathogens (bacteria, fungus, protozoa & nematodes) in the medium in which they inhabited. They had the capacity to bio-accumulate high concentrations of toxic chemicals in their tissues and the resulting wastewater became almost chemical-free. Earthworms had been reported to bio-accumulate “endocrine disrupting chemicals” (EDCs) from sewage which otherwise was not removed by our conventional sewage treatment plants.

The project was set out to provide a sustainable waste water treatment system for residents who were not connected to the sewer system thus reducing the possible spread of waterborne diseases. Beitbridge Municipality’s project aimed at eliminating sewer bursts and reducing land pollution. The project envisaged to improve the standard of living while reducing the cost of living by reducing water bills as a result from residents using recycled water. The reduction of sludge formation which required additional expenditure on landfill disposal was another priority.

The local authority’s vision is to create an odour-free process resulting in clean water, not potable but can be used for gardening and flushing toilets. The project needed to reduce the burden on the sewage treatment down the sewer system by treating domestic waste water at the source. The above objectives would be achieved by engaging Environmental Management Agency (EMA), council and all stakeholders. The council had to adopt the project before its implementation. The construction of domestic filters/decongestors had to be done. Construction of waste water trunk line and communal treatment plant had to take place. The return pipe which supplied recycled water for flushing and gardening had to be installed. Then the connection of houses to the domestic decongestors in place before a test run of the sewer system was done. The commissioning of the system after the monitoring and evaluation saw the project becoming a success. The project had 9 direct beneficiaries. There were no indirect and online beneficiaries. The beneficiaries comprised of 5 women (56%) and 4 men (44%).

The project had a total budget of $18 000. gender specific allocation had nothing. Gender in mainstream projects was allocated $2 700. The local authority provided its’ boardroom for a number of workshops held in capacitating its’ staff towards the project and the refreshments which were provided. Environmental Management Agency (EMA) which is Beitbridge City Council’s key stakeholder came up with $15 300. The amount from EMA included the capacity building workshops they held with the local authority on several occasions.

For the project to be a success, the council monitored the water quality for bacteriology. Some sensory evaluations (odours) were also in put in place. Some exercises of monitoring the turbidity (water clarity) have to be done. Checks on suspended solids concentration were also done as monitoring exercises. Initially, two houses were connected to test the system. The test run lasted for two months and implementers were satisfied with the results. Thereafter the other seven houses were connected. All the beneficiaries were interviewed by council staff and EMA personnel. That was all part of the monitoring and evaluation exercise.

Open defecation exposed women to risk of being raped especially at night. That project had improved their safety. The ward councillor of the area had led by example and that had earned her a lot of respect in the community. The discharge in the environment led to high risks of waterborne diseases. That burdened women the most as they were responsible for ensuring that the home was clean. Furthermore, women were the primary care givers for the victims of water borne diseases. The use of recycled water to flush toilets and water gardens improved the standard of living for children in particular and the entire households in general.

Electricity was required for powering the pumps. That alone meant that direct connections to Zimbabwe Electricity Supply Authority (ZESA) to the pumps were needed and a provision of solar backup power installed. The system was currently connected through power from one of the direct beneficiaries. Council would connect the system to the nearby council clinic’s solar system. Some earthworms died in domestic filters. That was because a local species of earthworms was used. Therefore a special type of Earthworms was added and it survived. The performance and reliability of the system relied on regular monitoring. There was need for pumping of waste water every day in the morning and late afternoon. That was to be done even during weekends and public holidays. That could solve by introducing float switches on pumps. The recycled water for flushing toilets had a bad odour. The smell disappeared due to continuous use of the system. The multiplication of worms in decongestors helped improve the treatment in the waste water.

“I promised that by 2018, I will have done it and of cause I have done it”, confidently said Sarudzai Moyo (Ward 4 Councillor and beneficiary of the project). The project brought positive power relations at household levels as it solved lots of disputes between landlords and tenants. Landlords were restricting tenants from using their toilets which were connected to the illegal sceptic tanks hence most tenants were resorted to the bush system. The bush system exposed most of them to thugs and the girl child risked being raped. Some houses had illegally connected their bathrooms and laundry pipes to discharge wastewater to the streets. All these illegal connections could meet with stiff penalties from the Municipality. They were now legally connected to their domestic decongestors hence they were free to interact with officers from the local authority.

The submersible pumps used at the communal treatment plant were powered by electricity. The costs of running the project could be reduced by connecting the pumps to solar power with backup batteries. The pumps needed close and regular monitoring to avoid flooding the communal plant. Non organic material should be removed from decongestors after twelve to twenty four periods to avoid flooding decongestors. Decongestors needed to be monitored from flooding which might kill the earthworms. Breeding of earthworms should be an ongoing exercise in order to be able to replace earthworms that die in decongestors. The project was easy to replicate since most council technicians were involved throughout the project implementation. It could also be replicated in new layouts and in areas lying below the trunk sewer line. The project could also be done in areas where there were frequent sewer bursts. Decongestors could be introduced in areas with recurrent sewer blockages so that they attend to all the blockages.