英語語言學(xué)習(xí)：純凈水凈化系統(tǒng)

(From an Omni Processor promotional video:)

Bill Gates: Over 2.5 billion people have no access to safe sanitation. We asked brilliant engineers to help us solve this problem, and one of those engineers actually has proposed a solution where the waste is valuable.

Man: The Omni Processor turns sewer sludge, which is kind of nasty, into clean drinking water, electricity, and ash that is pathogen free. This is where the sludge enters the machine. It goes up this conveyor belt, it's fed into these large tubes we call the drier, that's where we boil the sludge…

Antony Funnell: If you're thinking the first voice in that short audio clip sounded a lot like Bill Gates, send us your address here at Future Tense and we'll send you a gold star because it was the billionaire philanthropist starring in a promotional video for a new waste treatment machine called the Omni Processor.

I wanted to start today's program with the Omni Processor because it's such an impressive device, and because the waste it's particularly concerned with is human waste. And today's show, you see, is all about turning human waste from a problem into a future resource.

Hello Antony Funnell here, welcome to the program.

Aaron Janicki: It uses the energy in the sewage, as well as additional energy from garbage or by other assorted waste streams to power the processor. So it burns that material in a firebox. The firebox boils water that is sent to a steam engine, and the steam engine powers the plant.

Antony Funnell: That's Aaron Janicki from the company Janicki Bioenergy who've developed the machine.

Aaron Janicki: Energy from this steam engine process is used to dry the sewage, and when that happens it boils, and the vapour is recovered and it's filtered and cleaned and aerated and turned into extremely high quality drinking water. It takes about five minutes, the entire process, from start to finish.

Our first machine, which is a prototype, is actually getting deployed into the field right now, and we are in the process of commercialising the technology. We have hundreds of requests for the technology all over the world. We are in the process of rank ordering those requests in terms of priority, in terms of where the most impact can be made, and in terms of their ability to receive financing and the business model.

The really interesting thing about the Omni Processor is that it takes the sanitation industry and it turns it from a cost centre to the government into a profit centre for who's ever involved in running and owning this technology. And this is really what makes it innovative. So it highly incentivises the owner of the technology to make it work financially, to keep it running technically so that it can benefit them financially. So the Omni Processor, because it produces 70,000 litres per day, could service about 35,000 people just in drinking water every day.

Antony Funnell: Approximately 70,000 litres a day, and the machine is less than the size of a modest suburban house.

Now, the Omni Processor's focus is turning human waste into water and electricity, but around the world the big potential seems to be in converting sewage into fertiliser.

Dr Mats Johansson is a senior partner and consultant at the company Ecoloop in Sweden.

Mats Johansson: As a fertiliser we know that there is a really big potential. And we could say that not all of the nutrients and fertilisers needed in Swedish agriculture could be replaced, but maybe 25% or 40%, depending on if you discuss phosphorus or if you discuss nitrogen. This could be reused, and the farmers are interested and willing to cooperate with this. And what's really interesting is that we now have the knowledge and we know that we will also see benefits in the big waste water treatment plants when we take away a lot of the nitrogen, when we take away a lot of the phosphorus, it will be cheaper and easier and also more efficient to manage and operate this big waste water treatment plant.

Antony Funnell: And according to Mats Johansson, the simplest solutions are sometimes the best. One of the areas in which Sweden has directed its efforts is in urine diversion and utilisation.

Mats Johansson: As we have organised our systems and the techniques that we use, it's very low-tech really; collect the urine, where it flows by gravity in a pipe to a collecting tank, where we come with a tank cart and collect it and transport it to a big storage basin, and it's very important that this is airtight or with a lid on it, where we could store it for maybe three or six months. And then when it's perfectly available for fertilising and agriculture and where you could use the same kind of methods and machinery that when you spread cow manure or manure from pigs. And how to do this is something that we know, we have done research and development, so we could do this in a very efficient way today.

The problem with this is that you transport quite a lot of water. The urine from humans is not as concentrated as fertiliser, so there is research going on in Sweden and in other countries, how to reduce the volume of the urine without loss of nitrogen. That technology, it's being tested and researched but we have not seen it implemented yet. And when we do that, then we reduce the volume, then we can transport this fertiliser coming from humans far more and we could reduce the storage volumes needed and we could make the spreading of this fertiliser much more efficient.

Antony Funnell: Mats Johansson in Sweden.

Way across the world in rural Australia there's also growing interest in trying to use recycled urine and faeces as an alternative to chemical fertilisers. It's estimated that in Queensland alone, more than 150 farms make some use of what's called biosolid, a solid fertiliser product that's made from treated human waste.

Professor Mike McLaughlin is a soil scientist with the Australian research organisation, the CSIRO.

Mike McLaughlin: The utilisation is probably 75% or 80%, but the problem is Australia is such a large country and with a small population, there's just not enough biosolids for everybody in Australia who's on farming land to get hold of it. There are also issues of logistics because it does cost to transport. It is a more bulky and lower nutrient content material than normal fertilisers. So there are logistical reasons that are not all farmland would receive biosolids, and not all farmland is suitable to receive biosolids because the slope may be too steep, they may be too close to water supplies, maybe too close to residential land, concerns about smells, flies, these sorts of things. So it's the aesthetic issues that people would normally see first I think when you have biosolids used on land.

Antony Funnell: How good is it as a fertiliser? How good is it compared to, say, traditional chemical fertilisers that we tend to use?

Mike McLaughlin: It's very good because the trials have been done around Australia to show its economic value, and it can replace normal fertilisers. But it is applied in larger amounts because it has a lower nutrient content. Most fertilisers, for example, are going to be between 10% and up to 50% nitrogen, biosolids are going to be between 1% and 3% or 4% nitrogen, so there are much lower nutrient contents. You tend to have to add more to get the amount of nutrients that plants need. And it's probably a more slow release form of nutrient as well in that as the biosolids break down the nutrients are released to the plants rather than rapid release with commercially manufactured fertilisers.

Antony Funnell: Are there long-term benefits for our soil in returning biosolids to our fields?

Mike McLaughlin: Yes, I think it's really important we recycle nutrients back to the land, because if you think about it, there's all these trucks coming into cities with food laden on them to feed the urban population. In Australia more than 80% of the population is urbanised. So every day there's hundreds or thousands of trucks coming into cities bringing food, and that's bringing nutrients off the farming land into the city. The city water authorities have to treat those nutrients.

And the options then are, well, do you throw it back out in the ocean where you are you going to have problems with pollution? Do you allow it to escape to the atmosphere and there's concerns about greenhouse gas emissions, or do you try and re-utilise it back on land? And I think the reutilisation option is the one that's most sustainable, if you like.

Antony Funnell: So in Australia and Sweden, it's all largely been about recycling human waste for agriculture, but in Britain and other parts of Europe, attention has also focussed on the gas that can be generated from a sewage treatment process called anaerobic digestion. The end product is called biogas and it's used as a fuel.

Sarah Jewitt is an associate professor at the University of Nottingham.

Sarah Jewitt: Probably one of the biggest changes over the last 10 years or so in Europe has been the introduction of feed-in tariffs, which makes it much more profitable for industries to use anaerobic digestion technology to generate energy. So a sewage farms for instance, they often have anaerobic digestion units on site. They are usually big industrial concerns, they have a lot of waste flowing through them, so they can put the human waste through the anaerobic digestion unit and they can either generate electricity or they can purify the biogas that comes out and actually feed it into the gas grid. And increasingly incentives for the use of renewable energy makes it profitable or affordable for them to do that. So that has been quite an interesting trend.

There is also increasing use of co-digestion, obviously because sewage has been through our own bodies so we act a bit like an anaerobic digestion unit. An AD unit is a bit like a stomach really. So there's not a great deal of energy left in human waste, so what they tend to do is they co-digest it, and there's a plant not very far from me here in the Midlands called Stoke Bardolph and they have large acreage of contaminated land, land that can't be used to grow food for humans, so they produce energy crops on it, and so they grow crops and they feed it into the anaerobic digestion unit which increases its electricity yield or its gas yield, whatever they are using it for, and makes it a much more profitable enterprise for them. And then that powers a lot of the other processes that are going on in the sewage processing plant, as well as feeding electricity back to the grid.

Antony Funnell: And how significant is the contribution that those kind of systems can make to the electricity grid or to a region or a country's power system?

Sarah Jewitt: Each person only produces about 150 grams of faeces per day, so you wouldn't really think that it would add up to much, but then when you get a big plant…one of the biggest ones in the UK is Didcot in Oxfordshire, and in 2010 they made the news because they actually had 200 homes in Oxfordshire that were using gas produced from their own faeces, and that was being fed into the gas grid by the plant in Didcot, and they could use it for heating and cooking purposes.

Antony Funnell: And you're listening to Future Tense, I'm Antony Funnell, and today we're exploring the use of human waste as a potential resource and the global industry that's slowly building around it. Now, so far there's been lots of talk about potential. There's obviously lots of interest in utilising human waste, there's been lots of research, but it really feels like things are a little stuck. It's all very positive, as we've heard, but it does seem like it hasn't progressed to the next level.

Sarah Jewitt: Technically there's lots of capacity…and the sewage plants I think are really leading the way here, and legislation like the feed-in tariffs and legislation pushing the use of renewable fuels is all helping to provide incentives for investment and research and development in this sort of technology. So it's really quite exciting in terms of what's happening, we're in a real time of change.

But on the other hand there is the taboo factor, the yuk factor, and people don't really want to get…for obvious reasons, they don't want to get close to their own human waste, so the bottom line is the acceptability. So Sweden is quite an interesting example here because they had really strong political will in the 1990s to push urine diversion as part of the planning procedure, as part of the municipal government's authority, but they didn't really have sufficient attention to how the urine would be reused and to give incentives to farmers so that it was being collected in large enough quantities to make it worthwhile for farmers to actually come with mechanised equipment and spread it on the land.

So there is huge potential in terms of the savings that it could make the agricultural sector from buying fertilisers. But there's more that needs to be done on creating a whole interlocked set of incentives for people to use urine diversion but also for the infrastructure of its collection and storage on farm and use on farm, and also the environmental legislation to actually allow it to be permitted. At present farmers can't apply urine and be certified for organic farming. So there is scope for more research and development there to see what the risks are associated with that or the environmental consequences of urine being spread on the land. Because it contains nitrates, it can cause eutrophication just in the same way as animal manure or run-off from conventional fertiliser. So there are issues. But if there is political will and legislation in place then it's much more likely that those sorts of barriers will be overcome.

Antony Funnell: Sarah Jewitt from the University of Nottingham. And even in Sweden, it seems, the advances made several decades ago have now turned into a tale of frustration37 as much as progress.

Mats Johansson: In the mid-'90s we did a lot of pilots and research on urine diversion systems, and we could see that there were many benefits with the urine diverting systems. But on the other hand at that time the Swedish municipal water companies, waste water departments at the municipalities, they weren't really interested in this. So what happened was that we had pilot eco-villages, new technology that was underway, but no one really from the municipalities or from the government really moved in and said, okay, let's take this to the next level, let's go to scale, let's take the next step. When that really didn't happen, the political interest moved on to the questions of climate change and other aspects.

But what happened was that the solutions with sewer separations was really adopted maybe 10 years ago, something like that, in the countryside where we were talking about the on-site sanitation systems in Sweden. And what we've seen since then is a growing trend with sewer separating systems and new technologies coming, a lot of municipalities pushing for this in the countryside. And in Sweden we have approximately 1 million on-site systems, that is one-tenth of all the households have on-site systems, and we really now see a trend where we implement this and we also see an interest from the local farmers and the regional farming organisations, saying we are interested in this and we organise systems for storage and treatment of this toilet waste and the re-use in agriculture. That's really growing.

We have had three major investigations or commissions discussing the pros and cons of the re-use of sludge, and that has not been decided upon on the national level, and we are really at the moment waiting for the Swedish government to really decide upon the national targets for reuse and propose a new regulation for the reuse of all the kind of wastewater products. So it's really up to local political decisions at the moment, but hopefully in the future we will see more directed governance towards increased reuse of nutrients.

Antony Funnell: Frustration all around. But one country where sheer necessity is coming to the fore is China. We all know that mass urbanisation has caused major air pollution problems for Chinese cities, but they also now have a major sewage problem. Sarah Jewitt, if you'll recall, said the average human produces around 150 grams of waste a day. Well, multiply that by the urban population of China, which as I understand it is around 730 million people, and that's one hell of a municipal management problem, or one enormous opportunity, depending on the way you see the world.

But in China there isn't the same cultural disgust for reusing human waste that exists in other parts of the world.

Scott Chen is an entrepreneurial farmer who provides produce for the city of Tianshui, which has about 3.5 million residents.

Scott Chen: I actually grow cherries and apples with urine collected from school toilets. With urine as fertiliser, the fruits taste much better than with chemical fertiliser. We have feedback from our social media, like Facebook. I collect the urine from 31 schools. In these schools there are a special kind of toilets, urine diverting toilets, and almost 20,000 students and teachers are using them. Under these toilets is a urine tank. You just keep the urine in the tank for 2 to 3 months and then we can use it as fertiliser.

It is actually more expensive than chemical fertiliser because the schools are located in different places that are far away from each other, so I have to drive the car there to collect the urine and take it to the orchard, and there are no subsidies for this kind of work in China. Ironically, they do have subsidies for transporting chemical fertiliser. But it's worth it. The fruits are very tasty, people like them and people are willing to pay me a high price. It's our tradition, it's our ancestors' philosophy, to return all the organic matter to the field as a fertiliser. People in this country think that qualms about that are quite a bit silly. There are no restrictions to that in China. It's our tradition.

Heinz-Peter Mang: You can give the example of Beijing, in Beijing every day it's collected, between 6,000 and 7,000 tonnes of faecal material per day, collected by trucks. And if you have 60 cities similar or a little bit less dimensions than Beijing, you can imagine the amount of faecal material that is collected.

Antony Funnell: That's Heinz-Peter Mang a German engineer who's been working in China in the human waste reprocessing field for almost three decades. He talks about China now undergoing a 'waste revolution'.

Heinz-Peter Mang: You have areas like Sichuan in China, which is a vegetable and rice production area where there is a huge need for fertiliser, and you have more than 4,000 so-called fertiliser factories in this area where private business is combined with the public sector. The public sector is the collection sector, the private sector is the treating sector where they are mixing different kinds of organic waste to produce the best hygienised product for their local market and are making money out of it of course, because it's like black soil at the end, and when you do the right mixture between faecal material, between chicken manure, between cow manure or other assorted garbage, you can bring out the best kind of fertiliser.

In Beijing we have different kinds of projects depending on the background where they are coming from, so it means we have projects that are so-called township village enterprises, that means these are former villages which are now urbanised, and these villages have…one example in Beijing has a garden area where they are producing in the community vegetables and fertilisers and soil improver, and they have community tasks that is faecal sludge collection and treatment systems. They have a system that every day about 10 to 20 tonnes are collected by these small sucking trucks, brought to the treatment station where it is thermophilic treated, that means with high temperatures, even by adding coal.

Then after the biogas treatment system where gas is generated to disinfect the sludge, the sludge is then stored and diluted with water and then pumped by irrigation system in the greenhouse area where it serves as a soil fertiliser or soil improver in the drip irrigation system. So this is one example for an enterprise which was creating income but also solving the problem of the community. And for them it's kind of…it's not a kind of business because it's a social work to serve to the people. The business aspect is then the fertiliser aspect.

Antony Funnell: What sort of lessons are there for other countries from China's recent experience in dealing with the repurposing of organic waste?

Heinz-Peter Mang: I think the first lessons learned is that we need to discuss the cultural barrier, and when you are looking in the value from this material we can learn from China that the value of this material, mainly based on mineral phosphorus or nitrogen, this is a monetary value which is in China calculated and in many countries it is not calculated, so that we can learn from China.

Antony Funnell: That fear around safety, you know, people thinking that reusing waste is going to be dangerous and could possibly spread disease, that is a significant problem, isn't it, that perception problem. How do you overcome that really in countries that don't have the same kind of cultural understanding of the re-use of waste that China has?

Heinz-Peter Mang: The first is not to delude the waste between different kinds of wastes, then you can not more control contaminants. That means when you have a well structured household sanitation system, it keeps the house sanitation system and collects the waste at the household level, then people will not mix in the toilets any garbage. But when you bring it to a bigger system where you cannot control the contaminants, people will use any kind of waste system as a garbage a system where everything is mixed in, even with production waste, industrial waste or medical waste.

And the second is that you have a separate system for collecting medical wastes, you have a separate system you needed for food waste, that means you should have other alternatives than people using the human faeces collection system as a general waste system.

Antony Funnell: Heinz Peter Mang from the University of Science and Technology in Beijing.

So, as with renewable energy technology, China's sheer population size, its environmental concerns and its manufacturing capacity could provide the global kickstart to really get the human waste reprocessing industry up and fully firing.

Which brings us nicely back, full-circle, to the Omni Processor, because while the machine has enormous potential for use in places like Europe, North America and Australia, it's in the developing world that Aaron Janicki believes it will find its initial market and success.

Aaron Janicki: We are focusing mostly on developing countries, particularly in West Africa and India, and we are putting emphasis on urban communities first where we can really get a concentrated impact. And of course the first step is to process the sewage and kill all the pathogens in the sewage, that's the first thing that happens in our process. And the advantage of that is not only are you eventually treating that and cleaning it into pure drinking water, but you're also preventing that sewage from leaking into water streams and contaminating the rest of the water in the environment.

The model that we are currently pursuing is one where an entrepreneur would purchase the technology, receive his financing through a financing agency like the African Development Bank, the Asian Development Bank or the World Bank, and then they would quickly be able to pay back their loan by selling the outputs of the machine; the electricity and the clean drinking water. And of course they could also be taking tipping fees for the incoming sludge and incoming garbage, and we will support them remotely. And that will allow us to collect a huge amount of data about the performance of the machine.

It will also not require the skill of local labour to be on engineering level, a mechanic, someone that is capable of working on a truck will be sufficient to run the machine locally, and then our engineers will provide all necessary supports. This model also allows us to ensure that the machines are operating by our standards, from a water output quality and emissions standpoint, et cetera. And we have the ability to shut down the machines if something isn't working properly.

The really interesting thing is that it takes the sanitation industry and it turns it from a cost centre to the government into a profit centre for who's ever involved in running and owning this technology. And this is really what makes it innovative. So it highly incentivises the owner of the technology to make it work financially, to keep it running technically so that it can benefit them financially.

What we find throughout the developing world, our engineering teams have travelled to many different countries, throughout Africa and Asia, and what we find is there's a lot of treatment plants that have been put in place. But ultimately the governments are unwilling to pay the opex to continually run them. They may be willing to put in the initial capex but they can't stomach the continual opex payments. And so this is where this technology is very different, is because it pays for itself.

Mats Johansson: I would say if it takes five years or 15 or 55 years, I don't know, but we will end up using all the nutrients in the toilet waste, I'm sure of it. And which technology we will use, that is hard to predict. But I believe from what we've learned so far, reuse of urine and reuse of toilet water from black water systems will be one of the main alternatives at least. And then other considerations, all about maybe the economics and existing systems and also even cultural and social aspects, will affect what kind of systems for reuse that we will choose in future.

Antony Funnell: Mats Johansson in Stockholm, closing this edition of Future Tense. We also heard today from Aaron Janicki, Scott Chen, Sarah Jewitt and Mike McLaughlin.

Thanks to producer Karin Zsivanovits and sound engineer Steve Fieldhouse.

I'm Antony Funnell until next time, cheers!