At the end of yesterday’s class, we were discussing landfills and the hundreds of millions of tons of everyday garbage which are deposited into them each year in the United States. It’s a growing problem! Quite simply, we are running out of space to put our garbage. And this is especially true for solid organic waste: food scraps from home or food processing plants, waste from farms, that sort of thing. Did you know that two thirds of the waste sitting in our landfills is organic material? We have government recycling programs for materials like plastics, glass and metal, yet widespread solutions for organic waste materials haven’t really been addressed in the United States. I think this is just asking for trouble in the future. 首先这篇文章先描述了上节课所讲述的内容，landfill这种垃圾处理的方式，并且详细描述了这种方式的不足之处，从而引出后面的主题，一种新的垃圾处理的方法APS
So today I want to talk about a technology that offers a potential solution to the problem—Anaerobic Phased Solids digestion, or APS digestion.
First of all, what does anaerobic mean? Anyone?
Without oxygen?老师和学生以问答的形式开始讨论今天的新内容Anaerobic Phased Solids digestion，
Correct! APS digestion uses anaerobic bacteria, ones that thrive in the absence of oxygen, to consume, to break down organic material. 所谓的Anaerobic就是没有氧气，这种生词的处理方式我们之前是讲到很多遍的，不需要纠结生词的字母意思，但是后面的解释一定要听清楚。
Excuse me. Professor. Um…those anaerobic bacteria you are talking about…well, aren’t anaerobic bacteria also used in waste water treatment plants?紧接着学生提出了疑问，这点非常重要相当于指出了第二种处理垃圾的方式，这点是同学们很容易忽略掉的一点：以前曾经用这种方式去处理废水
Yes. They are. Would you like to explain this to the class?老师以问题的方式引出学生的回答
Sure! So when waste water is treated, one of the byproducts is a thick liquid called sludge. And aren’t anaerobic bacteria used to break down the sludge?
That’s right. Anaerobic bacteria have been used in waste water treatment for decades.
So how is this technology different?在这里很明显的要讲到这两种方式的不同之处。并且将会在后面的信息中讲到之前这种方式的缺点
But there was always a problem. 这里明确提出的缺点
In order to process the solid waste, the kind we find in landfills, you had to pretreat the solids to turn them into sludge.
First, by breaking the material apart mechanically into small particles and then adding a lot of water until you got a kind of thick, soupy mix that the equipment could handle. But that extra step took time and required a lot of energy. 后面的信息还是用到我们之前所说的列举的方式举出，这种方式不仅耗费能量耗费时间还会耗费金钱，这个部分也在题目中有体现
That sounds like it would cost a lot.
That’s right. But APS digestion is designed specifically to handle solid waste. So it is much more cost-effective.
The new technology processes organic waste in two phases. Remember, APS stands for Anaerobic Phased Solids digestion. 这里就正事提了新的科技并且还是同样按照列举的方式解释了他的两个phase两个阶段，列举的方式又再一次体现在了题目中
First, the waste material is loaded into a large, closed container, along with different types of anaerobic bacteria. The bacteria break the solids down into acids and hydrogen gas. The hydrogen is extracted and the remaining acids are transferred into a different container for the second phase of the process. There another type of bacteria converts the acids into methane gas. 在这里用页数语气的方式提出了跟之前的想法不同的新的内容，所产生的methane甲烷其实是没有害处的，因为它不会释放那大气中。同样体现在了题目中。
Aren’t hydrogen and methane gas bad for the environment though?
The answer in this case is no, because they don’t escape into the atmosphere. The gases are captured and can be burned to produce electricity, which saves a lot of money and ultimately decreases our need for fuels like petroleum and coal, which are not only expensive but are also polluting.
So organic waste from landfills could be processed this way?文章的最后就讲到了这种方式的优点
It is certainly one possibility. And APS digestion systems are very versatile. They can be installed just about anywhere. See, anaerobic digestion systems used at waste water treatment plants are huge tanks that hold thousands of gallons of waste water. But the APS containers are small enough to be set up on site, where the waste is generated, like at food processing plants or on farms. So garbage doesn’t have to be transported long distances.这个部分的有点描述继续以列举的方法进行描述：1.方便安装2.不用长距离的运输废品3.所产生的甲烷还可以去产生新的能源。