I nearly didn't watch the first episode of the BBC Two documentary, Welcome to Lagos. I saw a bit of the trailer and thought it might be a bit depressing, and while I often watch depressing things if I think I might learn something, I have to be in the right kind of mood to deal with it. But I did watch it and I am incredibly glad about that: Welcome to Lagos was fascinating, intimate, sobering in places, certainly, but uplifting and life-affirming in others.

The first episode focussed on the people living and working on one of the city's rubbish dumps, picking over each new delivery of trash for anything they could reclaim and sell. They collect plastic, fabric, metals, batteries, wires (for the copper) and numerous other items you wouldn't think are worth salvaging, swarming gracefully over the slithering piles and pouncing on treasures with their metal hooks. Many of the workers there also live in shacks on the dump itself (for at least some of the time), and a impromptu town has sprung up to service the workers, with cafés, shops, mosques and barbers interspersed with the housing shacks.

It's a very dangerous environment and — it goes without saying — a dirty one. You can just imagine what the dump smells like in the heat, or when it floods in the rainy season. For that reason, I was fascinated by their clothes. While they were working, their clothes were obviously dusty and dirty, but when they finished they showered (still amid the rubbish) and put on spotless, beautifully pressed clothes. As someone who makes clean clothes look dirty and rumpled about three seconds after putting them on (in a clean environment), I was full of awed respect for how they managed to keep even one set of clothes clean on the dump.

They also featured a huge combined cattle market and slaughterhouse. I don't eat meat and expected to find those parts rather upsetting, but actually it was fascinating and rather admirable. It looks a bit chaotic, but actually it's highly organised. The cattle are bought and slaughtered on the spot (with seemingly little panic or fear from the animals, even though the place must stink of blood), and their carcasses immediately processed. Every part of the animal is used except the hair. One enterprising lad from an agricultural college spotted that all that lovely blood was going to waste, and now has a business scraping it up from the floor, boiling it up in huge drums and making what I thought he said was chicken feed from it. I'm not sure feeding cattle blood to chickens is a great idea, but you can't fault either his business sense or the recycling aspect.

One thing I really admired about the documentary was that it let people tell their own stories. There was a bit of narration, but mostly, the people who worked on the dump or in the cattle market talked to the camera themselves. They also gave video cameras to participants to film parts themselves, so it was quite an intimate portrait. I'm sure that the editing process influenced the eventual tone of the programme, but I got the feeling that the people involved were represented in the way that they would wish others to see them. Despite living in working in what we would think of as atrocious conditions, they were ambitious, eager for opportunity, funny and for the most part, they seemed quite happy.

There was a part in which Joseph, who works on the dump, showed us the home he shares with his wife and two daughters. He was rather drily pointing out all the items that rich people (who he clearly thought had more money than sense) had thrown out and he had rescued to furnish his home. There was bedlinen, torches, a radio and even a red teddy for his baby daughter. In other circumstances I would hope that they had washed the teddy and the bedlinen well given their origins, but as I mentioned earlier, the dump workers have superhuman laundry skills and the items were spotless. His look to camera said it all: they are obviously idiots to throw away perfectly good stuff, but it's their loss and my gain.

You might think that the dump would be a rather lawless place, but it is seemingly self-governing and quite ordered. Workers leave their shacks unlocked and their stashes of junk to sell unguarded. They elect a chairman from among their ranks who arbitrates in disputes. At one point, a newcomer is caught stealing, and hauled in front of the chairman, tied up. There's a lot of shouting, threats of death and violence, and the thief is beaten a bit, but in the end the chairman simply exiles him. He is taken off the dump and told that he will be killed if he ever returns. It sounded and looked a bit frightening, but it is obviously an effective system. If you co-operate and abide by the rules of the society, your fellow workers will help you, but if you break the rules, you'll be thrown out and lose the opportunity that the dump offers to make money.