A Ugandan chemist has found a way to use old cattle bones and food waste to make clean water. Timothy Kayondo turns the rubbish into activated carbon, which he uses to produce water purifiers. They’re being used in schools and hospitals. It is estimated that one in 10 people on the planet do not have a basic level of access to clean water. In this programme we find out about Timothy’s work and discover more ways people around the world are getting access to safe drinking water. Presenter: Jo Mathys Reporters: Mercy Juma, Celestina Olulode and Tom Colls Producers: Daniel Gordon and Tom Colls Image: Timothy Kayondo

How are Covid sniffer dogs, a sturdy bicycle scheme and balloons beaming down the internet getting on? We catch up with a few of the projects featured on our programme to see if they are making progress. In the UK we catch up with the sniffer dogs being trained to detect Covid 19. After promising results from a large trial, they’re onto the next stage of training. Meanwhile Wyson in Zambia has extended his bicycle purchase scheme for rural women and even had a bit of help from a BBC World Service audience member. We find out what happened after US company Loon launched giant balloons designed to beam down the internet to rural Kenya. And we hear from Dhruv Boruah, who has turned his attention from running plastic hackathons to a rather unusual underwater project. Produced and presented by Claire Bates Reporters: Richard Kenny and Tom Colls Image: Dhruv Boruah

Scientists are checking up on the health of forests by analysing the sounds in them. They test their vital signs by measuring the croaks, tweets and hums of resident creatures. If they can hear a full range of animals they can be confident an ecosystem is doing well. However, if gaps start to appear, it’s a sign something is up. Nick Holland hears more about how it works and how it’s being used to strike a balance between the needs of Papua New Guinea’s growing indigenous communities and the need to preserve the biodiversity of the forests they live off. Produced and presented by Nick Holland Image: The Nature Conservancy Repeat - first published 04 May 2021.

Training cows to use the toilet and a bouncy castle that fights climate change are some of the surprising solutions today. Humans have been training animals like dogs and horses for centuries. But how easy is it to train a cow? Well scientists in New Zealand and Germany have been successfully training cows to use a special latrine. The cows get a reward each time they pay a visit. The idea behind it is that by collecting their urine in the latrine, it won't release so much ammonia into rivers and streams. In this programme we are going to look at some unusual solutions to big problems, and solutions to unusual problems you might not know existed. We’ll also hear about a bouncy castle which fights climate change by absorbing CO2, and a project to help people with different size feet find shoes that actually fit. Presenter: Celestina Olulode Reporter and producer: Richard Kenny Image: Dr Matthews (Credit: Dr Caroline Bagshaw)

Meet the innovators who want to change gig work for the better. When we order a pizza on a Friday night or use a ride-sharing app to get home, it’s likely that the person providing the service is a ‘gig worker’ – a flexible employee who picks their own hours and gets paid per-job. The app-based gig economy provides convenience for consumers - and has become an increasingly important part of the global economy over the last 10 years. Workers can log on and off when they chose – but they are often managed by an absent algorithmic middleman, and don’t have access to basic workers’ rights such as sick pay, holiday pay or an hourly wage. But people around the world think that a fairer approach to gig work is possible – from a co-operative run by ex-delivery riders in London to a blockchain based ride-sharing app launching in India. But can these upstarts provide the flexibility and convenience that both workers and consumers have come to expect? Produced and presented by Craig Langran