A GLOBAL SOLUTION TO PROTECT WATER BY TRANSFORMING WASTE

十分之四的人由于卫生条件差而生活在危险条件下。事实上，由于发展中地区有一半人口没有卫生设施，联合国提出的到2015年将人口减半的目标，无法获得安全饮用水和基本卫生设施的人口比例似乎无法实现。该项目的重点是“城郊”环境，包括城市以外的地区，这些地区的特点是基础设施薄弱，难以获得正规的水和卫生服务。在这里，人们忍受着水污染、不健康和缺乏尊严。尽管有安全控制废物的意图，但坑式厕所等卫生系统最终成为“地洞”。为应对这一挑战，出现了诸如“社区主导的全面卫生”（CLTS）等倡议。它鼓励社区分析自己的卫生状况并建造低成本厕所。其中一个关键教训是，卫生既是一项社会挑战，也是一项技术挑战。鉴于此，我们组成了一个由自然和社会科学家组成的团队，通过汇集我们的才能、兴趣和专业知识来解决这个紧迫的问题。我们认为需要一种“社会技术”方法来帮助快速解决这个问题，并且只有由不同专家组成的混合团队才能做到这一点。提出的技术是基于厌氧消化（AD），即细菌在缺氧的情况下将有机物分解成含甲烷的沼气。AD是一种自然过程，发生在土壤、沼泽和沼泽中。然而，如果应用在密闭罐中，AD可以用来处理废物。AD是一种成熟的技术，特别是用于处理工业废水。AD过程依赖于几组细菌以合作的方式一起工作来分解废物。通常情况下，第一组将大的化学分子（如脂肪和碳水化合物）分解成更简单的分子。然后，另一组继续消化过程，将废物转化为更简单的形式，直到最终甲烷制造者将废物转化为沼气。这些群体紧密地生活在一个被称为生物膜的黏糊糊的群落中。通常在废水处理池中发现的生物膜类型被称为“污泥颗粒”，因为它们呈球形。每个颗粒的直径约为1mm。每个颗粒含有数百万细菌，理论上，消化废物所需的所有不同群体将存在于每个颗粒中。与在曝气池中进行的常规废水处理相比，AD具有许多优点。主要的优点是AD更便宜，因为不需要浪费能源将氧气泵入AD储罐。此外，由AD产生的沼气可以很容易地用于发电、供热或作为汽车燃料。由于这些原因，英国未来的废水处理基础设施很可能依赖于AD。因此，该项目的目标是发展一种基于人工智能的低成本系统，以安全和有效地处理家庭废水（污水和个人洗涤水）。该系统将把废物转化为沼气和有价值的产品，如肥料。该团队面临的挑战是双重的：(1)近郊环境中的卫生系统不是基于正式的污水管道网络，污水通过冲厕水输送。取而代之的是高固体废物。一个主要的挑战将是“重新设计”颗粒，使其高效、快速地消化高固体废水。(2)可能会有文化和社会问题阻碍最初的进展。拟议中的系统，以及它可能被使用的方式，可能不会为当地人所接受。我们将与当地人合作，将所需的社会科学与工程和科学相结合。通过这种方式，可以开发出“以用户为中心”的原型。

Four-in-ten people live in hazardous conditions due to poor sanitation. Indeed, with half the population of developing regions without sanitation, United Nations goals of halving, by 2015, the proportion of people without access to safe water and basic sanitation seem set to be missed.The focus of this project is the 'peri-urban' environment, which includes areas outside cities that are characterized by poor infrastructure, and poor access to formal water and sanitation services. Here, people endure water contamination, ill-health, and lack of dignity.Despite intentions to safely contain waste, sanitation systems such as pit latrines end up as "holes in the ground". Initiatives, such as 'Community-Led Total Sanitation' (CLTS), have emerged to tackle the challenge. It encourages communities to analyse their own sanitation situation and build low-cost toilets. One of the key lessons is that sanitation is a social as well as technical challenge.In light of this, we comprise a team of natural and social scientists, which has come together to address this pressing problem by pooling our talents, interests and expertise. We believe that a "socio-technical" approach is required to help to quickly address this problem, and that only a mixed team of different experts can do that. The proposed technology is based on anaerobic digestion (AD), which is the breakdown of organic matter by bacteria to methane-containing biogas, in the absence of oxygen. AD is a natural process, which occurs in soils, swamps and bogs. However, if applied in airtight tanks, AD can be used to treat wastes. AD is an established technology, particularly for the treatment of industrial wastewaters. The AD process relies of several groups of bacteria working together in a cooperative manner to break down waste. Typically, the first group breaks down large chemical molecules (like fats and carbohydrates) to simpler molecules. Another group then continues the digestion process to yet-simpler forms of the waste, until eventually the methane-makers convert the waste to biogas. The groups live very closely together in slimy communities, known as biofilms. The type of biofilms commonly found in wastewater treatment tanks are known as 'sludge granules', due to their spherical appearance. The diameter of each granule is approximately 1 mm. Each granule contains millions of bacteria and, theoretically, all of the different groups required to digest the waste will be present in each single granule.AD has many advantages over more conventional types of wastewater treatment, which are carried out in aerated tanks. The chief advantage is that AD is cheaper, as there is no need to waste energy on pumping oxygen into the AD tanks. In addition, the biogas produced by AD can be readily used for electricity generation, heat production or as a vehicle fuel. It is likely that future wastewater treatment infrastructure in the UK will rely on AD for these reasons.Thus, the objective of this project is to develop a low-cost system, based on AD, for the safe and efficient treatment of domestic wastewater (sewage and personal washing water). The system will convert waste to biogas and valuable products, such as fertilisers.The challenges facing the team are two-fold:(1) The sanitation system in the peri-urban environment is not based on a formal sewerage network of pipes with sewage transported by flushing water. Instead, a high-solids waste will be present. A major challenge will be to 're-engineer' granules to efficiently - and quickly - digest high-solids wastewater. (2) There may be cultural and social issues impeding initial progress. The proposed system, and the way it might be used, may not be acceptable to local people. We will engage with local people and integrate the social science required, with the engineering and science involved. In this way, a 'user-centred' prototype can be developed.