In 1969, the vocal musical group The Fifth Dimension wrote a song about the coming of the Age of Aquarius, which would be filled with “harmony and understanding”, an age filled with humanity, universal love, and light. Well, we might still be waiting for the emergence of the first few of these, but perhaps we are finally seeing the true dawn of the age of light. Los Angeles is set to ink a deal to build a solar farm that could provide 7% of the city’s electricity at an astonishingly low cost of $0.020/kWh with battery power at $0.013/kWh to even out electricity provided to the grid. This new solar plant will create a 0.4 GW power plant, producing 876000 kWh of electricity annually, without the need to burn any fuel or consume any water. To put those numbers in perspective, electricity produced by natural gas is approximately $0.04/kWh, with coal at $0.05/kWh. Large fossil fuel and nuclear power plants typically produce 0.5 to 1 GW. This is a good start to nearly completely decarbonize the large electrical power needs of this city. It is amazingly economical and also desperately needed to slow climate change due to the release of CO₂ into the atmosphere from the combustion of fossil fuels. What does this dawn of the “age of light” mean for future environmental technologies? One option long researched by environmental scientists is photocatalytic water treatment. However, decades of research have failed to produce impactful commercial processes. Given the importance of integrating solar power into our water infrastructure, however, it may be premature to give up on this general direction of research. The advent of inexpensive solar-produced electricity, combined with affordable storage, could enable more direct approaches by using solar electricity to drive electrochemical processes, particularly at decentralized or remote treatment locations, although there are many challenges for applications using these electrochemical technologies. The main problems are associated with side reactions produced with the different electrodes, and the low conductivity of drinking water. Mixed metal oxide electrodes (MMOs), also known as dimensionally stable anodes (DSAs), have been used for years for chlorine gas production in salt solutions, as these electrodes have low overpotentials for chloride ions, making them effective for producing disinfectants and oxidizing organic matter. Boron-doped diamond (BDD) electrodes have high oxygen overpotentials, making them better suited for direct oxidation of organic contaminants in water, and they can have a side benefit of producing ozone and hydrogen peroxide disinfectants. BDDs, however, are many times more expensive than MMOs, although prices for both electrodes could decrease with advances in materials and through mass manufacturing. In water treatment applications MMOs and BDDs unfortunately produce, to different extents, chlorates, perchlorates, bromates, Trihalomethanes, and other disinfection byproducts. The development of electrodes better targeted to drive specific reactions without these unwanted byproducts could help advance direct electrochemical applications in water treatment. The low conductivity of water is a particular concern for environmental engineers designing systems for water treatment, compared to industrial processes in which highly conductive electrolytes can be used. Such environmental electrochemistry and water treatment studies are therefore welcome topics for ES&T and ES&T Letters. Most water treatment processes already use chemical disinfectants produced by electrochemical processes, such as chlorine, hydrogen peroxide, and ozone. Chlorine gas is produced using Pt catalysts and a cation exchange membrane made of Nafion, a polyperfluoroalkyl chemical, and NaCl brine solutions to generate Cl₂ at the anode and H₂ at the cathode. Hydrogen peroxide is produced using H₂ gas, a palladium catalyst, and a chemical mediator such as anthraquinone. Both of these disinfectants are generated off site and then transported on site for use. Methods that do not rely on precious metals and processes that could be implemented at the point of use could help enable more sustainable processes and improve safety by avoiding their transport over long distances. Ozone and ultraviolet light can be produced locally, so these processes could be more easily be integrated into a solar energy-drivenwater treatment process train. Although it may seem improbable today, there may also be applications of electrochemical reactors for used water treatment. For many years, placing membranes into domestic wastewater was considered to be impractical, but today membrane bioreactors are common for used water treatment. Perhaps the same story will unfold for electrochemical systems such as microbial fuel cells or for ammonia recovery using electrochemical separation processes, which are currently nascent treatment processes that are not yet practial for commercial applications. One niche electrochemical treatment system that has reached commercial production is an advanced electrochemical reactor developed by researchers at the California Institute of Technology for complete recycling of water in latrines that are off grid. The energy demands for these systems are quite high at 35 Wh/L, compared to conventional complete wastewater treatment systems that operate at 0.6 Wh/L, but the need for only a few inexpensive solar power panels at each site makes the system feasible. These systems are not suitable for potable water uses, however, due in large part to the production of chlorinated byproducts. Installed global solar power has already reached 0.5 TW, and it could double in just the next three or four years. Solar panels that float on water treatment plant ponds or sit on nearby land and produce the power more remotely are being installed and are already being integrated into treatment systems. Such solar arrays will reduce net electrical grid power consumption or provide additional inexpensive power to enable more effective or sustainable disinfection or chemical removals. Figuring out how to transform our water infrastructure in the coming age of light will certainly be a challenge, but it will be an enjoyable and needed adventure moving into our enlightened future. Views expressed in this editorial are those of the author and not necessarily the views of the ACS. This article has not yet been cited by other publications.

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让阳光进来

1969年，声乐团体The Fifth Dimension写了一首关于水瓶座时代到来的歌曲，其中充满了“和谐与理解”，一个充满着人性，普世热爱和光明的时代。好吧，我们可能仍在等待其中头几个的出现，但是也许我们终于看到了光明时代的真正曙光。洛杉矶即将达成一项建设太阳能发电厂的协议，以惊人的低成本（0.020美元/千瓦时）提供该市7％的电力，而电池电力以0.013美元/千瓦时的价格提供电力，以使向电网提供的电力平均分配。这个新的太阳能发电厂将创建一个0.4吉瓦的发电厂，年发电量为876000千瓦时，而无需燃烧任何燃料或消耗任何水。为了更准确地了解这些数字，天然气产生的电费约为$ 0.04 / kWh，煤炭价格为$ 0.05 / kWh。大型化石燃料和核电站通常产生0.5至1吉瓦的电量。这是一个几乎完全消除该城市大量电力需求的好开始。由于二氧化碳的释放，它非常经济，而且迫切需要减缓气候变化_2个通过化石燃料的燃烧进入大气。“光明时代”的曙光对未来的环境技术意味着什么？环境科学家长期研究的一种选择是光催化水处理。但是，数十年的研究未能产生有影响力的商业流程。但是，考虑到将太阳能整合到我们的水基础设施中的重要性，放弃这一总体研究方向可能为时过早。廉价的太阳能产生的电能与价格合理的存储相结合的出现，可以通过使用太阳能驱动电化学过程，尤其是在分散或偏远的处理场所，通过太阳能驱动电化学过程，从而实现更直接的方法，尽管使用这些电化学技术的应用面临许多挑战。主要问题与不同电极产生的副反应以及饮用水的电导率低有关。混合金属氧化物电极（MMO），也称为尺寸稳定阳极（DSA），已经在盐溶液中生产氯气多年，因为这些电极对氯离子的过电位低，使其有效用于生产消毒剂和氧化有机物。事情。掺硼金刚石（BDD）电极具有较高的氧超电势，使其更适合直接氧化水中的有机污染物，并且具有产生臭氧和过氧化氢消毒剂的副作用。然而，BDD的价格要比MMO贵很多倍，尽管随着材料的进步和大规模生产，两个电极的价格都可能下降。不幸的是，在水处理应用中，MMO和BDD会产生不同程度的氯酸盐，高氯酸盐，溴酸盐，三卤甲烷和其他消毒副产物。更好地针对于驱动特定反应而没有这些有害副产物的电极的开发可以帮助推进直接电化学在水处理中的应用。与可以使用高电导率电解质的工业过程相比，水的低电导率是环境工程师设计水处理系统的一个特别关注的问题。因此，此类环境电化学和水处理研究受到欢迎 更好地针对于驱动特定反应而没有这些有害副产物的电极的开发可以帮助推进直接电化学在水处理中的应用。与可以使用高电导率电解质的工业过程相比，水的低电导率是环境工程师设计水处理系统的一个特别关注的问题。因此，此类环境电化学和水处理研究受到欢迎 更好地针对于驱动特定反应而没有这些有害副产物的电极的开发可以帮助推进直接电化学在水处理中的应用。与可以使用高电导率电解质的工业过程相比，水的低电导率是环境工程师设计水处理系统的一个特别关注的问题。因此，此类环境电化学和水处理研究受到欢迎 ES＆T和ES＆T信函。大多数水处理工艺已经使用通过电化学工艺生产的化学消毒剂，例如氯，过氧化氢和臭氧。使用Pt催化剂和由Nafion，聚全氟烷基化学品和NaCl盐水溶液制成的阳离子交换膜生产氯气，以在阳极生成Cl ₂并在阴极生成H ₂。使用H ₂生产过氧化氢气体，钯催化剂和化学介质（如蒽醌）。这两种消毒剂都是在现场产生的，然后现场运输使用。不依赖于贵金属的方法以及可以在使用时实施的过程，可以避免长距离运输，从而有助于实现更具可持续性的过程并提高安全性。臭氧和紫外线可以在本地产生，因此这些过程可以更轻松地集成到太阳能驱动的水处理过程中。尽管今天似乎不太可能，但电化学反应器也可能用于废水处理。多年来，将膜放入生活废水中一直被认为是不切实际的，但如今，膜生物反应器已普遍用于废水处理。对于诸如微生物燃料电池的电化学系统或使用电化学分离工艺进行氨回收的情况，也许同样的故事将会揭开序幕，这些工艺是目前尚不实用的新生处理工艺。由加利福尼亚理工学院的研究人员开发的一种先进的电化学反应器是一种已实现商业化生产的利基电化学处理系统，用于完全回收离网厕所中的水。与以0.6 Wh / L运行的常规完整废水处理系统相比，这些系统的能源需求很高，为35 Wh / L，但是每个站点仅需要几个便宜的太阳能电池板就可以使该系统可行。这些系统不适用于饮用水，但是，很大程度上是由于产生了氯化副产物。全球已安装的太阳能发电量已达到0.5 TW，并且可能在未来三到四年内翻一番。漂浮在水处理厂池塘上或坐在附近土地上并在更远的地方产生电能的太阳能电池板正在安装中，并且已经集成到处理系统中。这种太阳能电池阵列将减少电网的净电力消耗或提供额外的廉价电力，以实现更有效或可持续的消毒或化学去除。弄清楚如何在即将到来的光明时代改变我们的水基础设施无疑将是一个挑战，但是这将是进入我们开明的未来的愉快而必要的冒险。本社论中表达的观点只是作者的观点，不一定是ACS的观点。