廁所革命：現(xiàn)代城市與城市貧民窟中對水污染控制的改善與廢水再利用

哈拉爾德·格林德爾，托弗·A·拉森/Harald Gründl, Tove A. Larsen

龐凌波 譯/Translated by PANG Lingbo

托弗·A·拉森，瑞士聯(lián)邦水產(chǎn)科學(xué)與技術(shù)研究所

為城市貧民窟提供更智能的廁所

在世界各地，有近26億人口使用不安全的廁所，甚至在開敞的環(huán)境中排泄。缺乏適用的衛(wèi)生設(shè)施導(dǎo)致了嚴(yán)重的腹瀉，每年有超過160萬人因此死亡[1]。健康衛(wèi)生的設(shè)施與手部清潔能夠很大程度地降低腹瀉的致病幾率[2]。然而，通常發(fā)展中國家水資源都非常昂貴[3]，并且由于水資源的匱乏，洗手的問題經(jīng)常被忽視。眾所周知，改善衛(wèi)生條件的“千年計(jì)劃”沒有完全實(shí)現(xiàn)，但正如鮑姆等人所指出的那樣[4]，實(shí)際情況可能比一般預(yù)期的還要糟糕。原因在于“改善衛(wèi)生條件”的定義只涉及個人的衛(wèi)生，而忽視了城市衛(wèi)生的所有方面，其中包括安全的處置或處理廁所廢物。城市貧民窟中衛(wèi)生基礎(chǔ)設(shè)施缺乏導(dǎo)致廁所污水滲入地下水和灰水流入地表水的現(xiàn)象，同樣對環(huán)境產(chǎn)生了不利影響。

藍(lán)色分流廁所的故事起始于2011年由比爾及梅琳達(dá)·蓋茨基金會（BMGF）啟動并資助的“廁所創(chuàng)新大賽”項(xiàng)目。來自瑞士聯(lián)邦水產(chǎn)科學(xué)與技術(shù)研究所（Eawag）和設(shè)計(jì)公司EOOS的一個團(tuán)隊(duì)是在大賽第一輪獲得資金支持的8個團(tuán)隊(duì)之一。比賽的目標(biāo)是為低收入國家的城市貧民窟帶來可負(fù)擔(dān)的、可持續(xù)的包括洗手功能在內(nèi)的衛(wèi)生設(shè)施。而比賽規(guī)則要求廁所必須回收所有資源，并且可以在不連接任何網(wǎng)絡(luò)——不論是電網(wǎng)、水網(wǎng)還是排水系統(tǒng)——的情況下運(yùn)行。另外，該廁所應(yīng)能夠?yàn)閭€人清潔提供水資源，整體的成本應(yīng)控制在每人每天5美分以下。

對于城市貧民窟地區(qū)，修建排水管和污水處理廠成本高昂，遙不可及。在許多情況下，貧民窟都是無基礎(chǔ)設(shè)施建設(shè)的臨建區(qū)域。我們開發(fā)了一個服務(wù)規(guī)模約為1000人的完整衛(wèi)生系統(tǒng)，貫穿從收集、儲存、運(yùn)輸?shù)劫Y源再利用的整個衛(wèi)生設(shè)施產(chǎn)業(yè)價(jià)值鏈。藍(lán)色分流廁所將未稀釋的尿液、糞便和受污染的沖水分離，以便有效回收資源。通過多屏障系統(tǒng)（在水冷壁內(nèi)）處理水質(zhì)供在地重復(fù)利用。我們的概念是以大約1000人的規(guī)模從場地之外的尿液和糞便中回收資源，這在當(dāng)今的技術(shù)手段下，顯然已具備可行性。

藍(lán)色分流廁所（圖1）醒目又易于使用，而且同時適合習(xí)慣沖洗和擦拭者使用（沖洗者用水清潔肛門，擦拭者則使用廁紙）。水冷壁可以在任何時候提供安全的自來水，并為大約10個用戶（每天50次使用）設(shè)計(jì)。這款廁所推出了新一代的尿液離心脫水馬桶（UDDT），這種馬桶通常并不受用戶歡迎，特別是對于那些沖洗者而言。藍(lán)色分流廁所有洗手用的水池、個人清潔用的蓬蓬頭（用于肛門清潔和經(jīng)期衛(wèi)生），以及用于馬桶前部的沖水功能。

水冷壁中創(chuàng)新的水循環(huán)技術(shù)，確保可以獲取無病原體的清潔的水。這種在地的水處理僅在馬桶的三流分離情況下才可能發(fā)生。尿液、糞便與沖洗水互不混合，但仍會有部分糞便和尿液污染廢水。不過與抽水馬桶相比，這種馬桶水污染程度較低，這也是為什么水冷壁可以在現(xiàn)場安全地處理廢水并以一種節(jié)能的方式回收它。

在地水循環(huán)系統(tǒng)是一個不排水的封閉體系，可以防止城市污染與貧民窟積水。由于使用過（比如用濕手碰過）的水必須進(jìn)行更換，但可以使用少量其他廢水或地表水，并在水冷壁中處理。生物處理和超濾膜是水回收技術(shù)的重要組成部分?，F(xiàn)代城市的大規(guī)模飲用水生產(chǎn)依賴于相同的科技，但需通過頻繁的、大量消耗能源的反沖洗來去除堵塞細(xì)胞膜的生物膜。藍(lán)色分流廁所的超濾膜則不需任何的圍護(hù)，這得益于家庭飲用水技術(shù)的最新發(fā)展，即由Eawag開發(fā)的所謂的重力驅(qū)動膜技術(shù)[5]。生活在生物膜與反應(yīng)器的沉淀物上的高等生物保持著膜的開放，而重力本身就提供了足夠的壓力來通過膜過濾水。在潔凈水箱中，活性炭吸附不可降解的有機(jī)物，少量Cl則抑制了微生物的生長。這使得廁所非常節(jié)能，因?yàn)樗鼪]有外部壓力，只需要提供O2來降解有機(jī)物，而不必保持膜的開放。我們僅需要實(shí)現(xiàn)這種簡易的水處理，因?yàn)榉衷吹拇胧┲粫o清潔和沖水帶來微量的尿液和糞便。

藍(lán)色分流廁所將從很多方面改善人們的生活。人們將根本上通過安全廁所和觸手可及的洗手設(shè)施改善個人的清潔衛(wèi)生。在城市的尺度上，衛(wèi)生水平也將得到大幅的提升，就地為城市農(nóng)業(yè)提供生產(chǎn)的肥料也能夠得以實(shí)現(xiàn)。可以想象，當(dāng)水循環(huán)的理念推廣至淋浴站和洗衣房，對人們的生活產(chǎn)生強(qiáng)烈影響的同時，也會減少帶來的蚊子滋生風(fēng)險(xiǎn)的積水，城市環(huán)境也將得以改善。

我們在烏干達(dá)坎帕拉測試了第一個藍(lán)色分流廁所的工作模型。在為期3周的時間內(nèi)，人們可以在一個臨建區(qū)域的社區(qū)衛(wèi)生中心使用廁所。

隨后，兩個擦拭者家庭，以及兩個沖洗者家庭共享了這個廁所，就像“現(xiàn)實(shí)生活”中的情況一樣?？傮w下來，據(jù)托拜厄斯等人的報(bào)道，我們共進(jìn)行了1500次采訪[6]。

大多數(shù)人對廁所的評價(jià)都是正面的，對可洗手、清潔與沖水功能的反饋?zhàn)顬檎?。也有一些批判性的觀點(diǎn)，導(dǎo)致了在肯尼亞第二次實(shí)驗(yàn)之前對廁所進(jìn)行的改造。最重要的變化在于尺寸的縮小，以便更好地契合現(xiàn)有廁所的上部構(gòu)造，并以電動泵代替腳踏泵——許多人擔(dān)心小孩與老人可能沒有力氣使用腳踏泵。第二次改進(jìn)廁所的實(shí)地測試是在肯尼亞內(nèi)羅畢進(jìn)行的。人們對廁所給出了正面的評價(jià)：100%的人特別喜歡廁所的外觀，95%的人認(rèn)為它使用方便，大約94%的受訪者會將它推薦給家人和朋友。

藍(lán)色分流廁所目前僅作為一種原型存在，它尚未投入市場。其中最難點(diǎn)在于找到相信這一系統(tǒng)的工業(yè)合作伙伴。我們建立了一種商業(yè)模式，以租用

Smarter toilets for urban slums

Worldwide, almost 2.6 billion people use unsafe toilets or even defecate in the open. Lack of proper sanitation causes severe diarrhea, killing more than 1.6 million people every year[1]. Hygienic sanitation and hand washing can reduce the occurrence of diarrhea significantly[2]. Water is generally expensive in developing countries[3]and with little water available, hand washing is often neglected. It is wellknown that the millennium development goals for improved sanitation was not realised, but as pointed out by Baum et al.[4]the situation may in reality be even worse than normally anticipated. The reason is that "improved sanitation" is defined only with respect to personal hygiene, while neglecting all aspects of urban hygiene, including safe disposal or treatment of toilet waste. Lack of sanitation infrastructure in urban slums also lead to detrimental environmental effects, primarily through infiltration of latrine effluent to groundwater and run-ffi of greywater to surface water.

The story of the Blue Diversion Toilet began in 2011 with the Bill & Melinda Gates Foundation(BMGF) initiating and funding the "Reinvent the Toilet Challenge" (RTTC). A team from Eawag (the Swiss Federal Institute of Aquatic Science and Technology) together with the design company EOOS was among the eight groups receiving a grant in the first round of the RTTC. The goal was to bring affordable and sustainable sanitation including hand washing to urban slums in low-income countries. The rules of the competition were that the toilet had to recover all resources and operate without connection to any grids, be it an electricity grid, a water supply grid, or a sewer system. Furthermore, the toilet should provide water for personal hygiene, and total costs should be below 5 US cents per person and day.

Building sewers and treatment plants is expensive and out of reach for urban slums, which are in many cases informal settlements where cities have no interest in installing infrastructure.We developed a holistic sanitation system at the scale of around 1000 people that works across the entire sanitation value chain from capture, storage and transport to reuse of resources. The Blue Diversion Toilet separates undiluted urine, feces and contaminated flush-and-wash water in order to allow for efficient resource recovery. A multi-barrier system(in the Water Wall) treats the water for on-site reuse.The idea is to recover the resources from urine and feces ffi-site at a scale of around 1000 persons. This is clearly feasible with today's technology.

The Blue Diversion Toilet (Fig. 1) is attractive and easy to use, and suitable for both washers and wipers (washers use water for anal cleansing; wipers use toilet paper). The Water Wall provides safe running water at all times and is designed for around 10 users (50 uses per day). The toilet presents a nextgeneration version of the urine diverting dehydrating toilet (UDDT), which is usually not very popular among users, especially not amongst washers. The Blue Diversion Toilet has a washbasin for hand washing, a showerhead for personal hygiene (for anal cleansing and menstrual hygiene), and a flush function for the front part of the toilet.

The innovative water recovery technology in the water wall ensures the availability of pathogenfree, clean water. This on-site water treatment is only possible due to the three-stream separation in the toilet pan. Urine, feces and the flush and wash water do not mix, but some fecal matter and some urine still contaminate the wastewater. However, compared to a flush toilet, the contamination of the water is very low. This is why the water wall can treat the water safely on-site and recycle it in an energy-efficient way.

The on-site water recovery system is a closed system without water discharge, preventing urban pollution and stagnant water in the slum. The water removed through usage (e.g., by wet hands) must be replaced, but small amounts of other wastewaters or surface water can be used and treated within the Water Wall. Biological treatment and the ultrafiltration membrane is the most important part of the water recovery technology. Large-scale drinking water treatment in modern cities relies on the same technology, but in a form that requires frequent and energy-intensive back-flushing to remove the biofilm that clogs the membrane. The ultrafiltration membrane in the Blue Diversion Toilet does not need any maintenance thanks to a recent development in household drinking water technology, the so-called gravity-driven membrane technology developed at Eawag[5]. Higher organisms living on the biofilm and the sludge in the reactor keep the membrane open and gravity alone supplies enough pressure to filter the water through the membrane. In the clean water tank, activated carbon adsorbs the non-degradable organic matter, and a small amount of chlorine prevents microbial growth.This makes the toilet extremely energy-efficient because it works without external pressure and only has to provide oxygen for degradation of organic matter and not for keeping the membrane open.We can only achieve such easy treatment because of source separation that only allows for traces of urine and feces to enter the wash and flush water.

The Blue Diversion Toilet would improve people's life in many aspects. People would primarily be able to improve their own personal hygiene through a safe toilet with access to hand washing.On an urban scale, hygiene would also be highly improved and a local fertiliser for urban agriculture would be available. It is very well conceivable that the idea of the water recycling could be extended to showers and laundry stations, with strong impact on people's daily life and an improved urban environment with less stagnant water leading to risks of mosquito breeding.

We tested the first working model of the Blue Diversion Toilet in Kampala, Uganda. During three weeks, people were able to use the toilet in a community sanitation centre in an informal settlement.

Afterwards, first two families of wipers, then two families of washers shared the toilet, as would be the case in "real-life". Overall, we were able to conduct 1500 interviews, as reported by Tobias et al[6].

Most people evaluated the toilet positively, with most positive responses on the availability of water for hand washing, anal cleansing and flushing. There were also critical points, resulting in a remodeling of the toilet before the second trial in Kenya. The most important changes was a decrease of size to allow for a better fit in existing toilet superstructures and the use of an electric pump instead of a foot pump.Many people were afraid that children and elderly would not have the strength to use the foot pump.The second field test with the improved toilet took place in Nairobi, Kenya. People evaluated the toilet positively. They especially liked how the toilet looks(100%) and that it is easy to use (95%). Around 94%of the people interviewed would recommend it to family and friends.

The Blue Diversion toilet only exists on the level of a prototype; it is not market-ready yet. The most difficult issue is to find industrial partners that believe in the system. We have set up a business model based on renting of the toilet and paying on a weekly basis for the necessary transport services. We anticipate a franchising model where a local business get the license to set up the system in a given area. Although the single systems can function on a small scale, only massproduction can make the toilets and the treatment technology cheap enough to secure the low cost service that slum dwellers can afford. This is a major endeavor and it is understandable that industries are hesitant to take on this task. As one stepping-stone, we work on the separate industrialisation of the water wall, which is considerably simpler to produce than the entire system.廁所和每周為必要的運(yùn)輸服務(wù)付費(fèi)為基礎(chǔ)。我們預(yù)計(jì)這將成為一種特許經(jīng)營模式，在這種模式下，當(dāng)?shù)仄髽I(yè)獲得許可證，便可以在特定地區(qū)建立該系統(tǒng)。盡管單個廁所系統(tǒng)可以在小范圍內(nèi)產(chǎn)生作用，但只有大規(guī)模的生產(chǎn)，才能夠使廁所和水處理技術(shù)足夠便宜到保證貧民窟的居民能夠負(fù)擔(dān)這種低成本服務(wù)。這是一項(xiàng)重大舉措，可以理解行業(yè)在采取行動時的猶豫不決。作為一塊敲門磚，我們正致力于水冷壁的分離產(chǎn)業(yè)化——這比整個系統(tǒng)的生產(chǎn)要簡單得多。

1 藍(lán)色分流廁所/Blue Diversion Toilet （圖片來源/Source: ?Eawag/EOOS）

2.3 Laufen公司產(chǎn)品“Save!”/Laufen save!（圖片來源/Sources: ?Laufen）

4 “尿袋”設(shè)計(jì)/Scheme "Urine Trap"（圖片來源/Source: ?EOOS）

為更智慧的城市提供更智能的衛(wèi)生設(shè)施

如果這是一種極其有效的保護(hù)環(huán)境的方法——比建造排污管道和最終的污水處理廠要更有效，那么就把排泄物保存并轉(zhuǎn)化為有益如化肥的產(chǎn)品。同樣的，現(xiàn)場處理和回收水提供了最大限度的地表水保護(hù)及水的再利用。

更便捷的處理廢水的關(guān)鍵在于尿液分離。尿液包含人體新陳代謝所產(chǎn)生的大部分營養(yǎng)物質(zhì)，正是這些營養(yǎng)物質(zhì)使廢水處理變得困難且昂貴[7]。移除糞便則要容易得多，通過沉淀和簡單的生物處理即可。這一點(diǎn)不僅在城市貧民窟中成立，在世界各地的現(xiàn)代城市中也同樣適用。這就是為何許多廢水研究員對尿液分離感興趣，在像巴黎和香港這樣的現(xiàn)代城市也是如此[8-9]。有許多技術(shù)用于尿液分離，或是用于養(yǎng)分分離，或是用于養(yǎng)分回收[10]。其中尤其成功并已準(zhǔn)備工業(yè)化的是“Vunatechnology”1）。一度阻礙這種技術(shù)實(shí)施的是一種具有吸引力的尿液分離沖水馬桶。

已準(zhǔn)備上市的尿液分離馬桶“Save!”（圖2、3）消除了這個阻礙。這款馬桶由奧地利設(shè)計(jì)公司EOOS設(shè)計(jì)，將由瑞士大型衛(wèi)生設(shè)備公司LAUFEN生產(chǎn)。這款馬桶將會在2020年初在歐洲上市。

“Save!”是首個符合現(xiàn)代工業(yè)標(biāo)準(zhǔn)的尿液分離沖水馬桶。它能被動地將尿液從固體和沖水中分離出來。這款產(chǎn)品的關(guān)鍵創(chuàng)新點(diǎn)在于由EOOS設(shè)計(jì)公司所發(fā)明的“尿袋”，它可以僅僅依靠表面張力將尿液越過馬桶的水面導(dǎo)向一個隱蔽出口（圖4）。這就是著名的“茶壺效應(yīng)”。LAUFEN將這個概念運(yùn)用于到一種新型的馬桶上，這種馬桶形式上近似一個陶瓷碗，智能的形式可以引導(dǎo)水流、優(yōu)化“Save!”的性能。這種表面適用于所有的馬桶類型，而隱藏其中的發(fā)明確保它與任何其他高檔馬桶別無二致。這種顛覆性的設(shè)計(jì)代表了習(xí)以為常的產(chǎn)品的一種新形式，可以在可持續(xù)的污水處理的未來里起到關(guān)鍵作用。

在中國特定的背景下，“Save!”的巨大優(yōu)勢體現(xiàn)在集中式和分散式水回用的更好適用性。特別是在世界上最缺水的城市之一——北京，對水的需求的不斷增加呼吁著水循環(huán)技術(shù)的創(chuàng)新[11]。在2014年地表水和再生水幾乎占到供水總量的一半的情況下，如果能簡化廢水處理，不必進(jìn)行養(yǎng)分去除，將是非常有助益的。鑒于北京是小型水循環(huán)技術(shù)產(chǎn)品的國際中心[12]，那將意味著，如果尿液分離成為標(biāo)準(zhǔn)，當(dāng)?shù)毓I(yè)將會在中國乃至全球范圍內(nèi)其他缺水地區(qū)獲得巨大的利潤。□

Smarter sanitation for smarter cities

Containing excreta and transforming it to beneficial products like fertiliser if an extremely effective way of protecting the environment - much more effective than building sewers and - eventually - treatment plants.In the same way, treating and recycling water on-site provides maximal surface water protection and water reuse.

The key to easier treatment of wastewater is urine separation. Urine contains most of the nutrients from the human metabolism and it is the nutrients that makes wastewater treatment difficult and expensive[7]. Feces are much more easily removed by sedimentation and simple biological treatment. This is not only true in urban slums, but also in modern cities all over the world. This is why many wastewater researchers are interested in urine separation, also in modern cities like Paris and Hong Kong[8-9]. Many technologies exist for the separate treatment of urine, either for nutrient removal or nutrient recovery[10]. Especially successful and ready for industrialisation is the "Vuna-technology"1). The main hurdle for implementation has been the absence of an attractive flush toilet with urine separation.

The development of the market-ready urineseparating toilet Save! (Fig. 2, 3) removes this hurdle. The toilet was designed by EOOS, an Austrian design ffiice, and will be produced by LAUFEN, a major Swiss sanitation company. The toilet will be on the market in Europe by early 2020.

Save! is the first urine-diverting flush toilet to meet modern industry standards of conventional toilets. It passively separates urine from solids and flush water. The product's key innovation is a "Urine Trap" (www.urinetrap.com) invented by EOOS Design, which directs urine across the toilet's surface towards a concealed outlet using only surface tension (Fig. 4). This is known as the "teapot effect". Laufen applied this concept to a new form of toilet featuring a ceramic bowl that is intelligently shaped to guide the water flow and optimise the performance of Save! The interface is universally applicable to all toilet typologies and the hidden innovation ensures it is indistinguishable from any other high-end toilets. This disruptive design represents a new format for a familiar product that could play a key role in the future of sustainable wastewater management.

The large advantage of Save! in a specific Chinese context is the better applicability of centralised and decentralised water reuse. Especially in the Region of Beijing, one of the most waterscarce cities in the world, the increased demand for water calls for innovations in water recycling technology[11]. With surface water and reclaimed water accounting for nearly half of the water supply in 2014, simplified wastewater treatment without nutrient elimination would be extremely beneficial. Since Beijing is an international centre for the production of small-scale water recycling technologies[12], the local industry would profit immensely if urine separation would become standard, not only in China, but also in other waterscarce regions globally. □

注釋/Note

1）經(jīng)過多年的研究，Eawag已經(jīng)能夠開發(fā)出一種用尿液生產(chǎn)安全濃縮肥料的方法[13]。生物處理能夠穩(wěn)定尿液，并去除有機(jī)物和意味。經(jīng)過生物處理后，活性炭柱出去通過尿液排出的剩余藥物和激素。隨后的蒸餾濃縮尿液，以生產(chǎn)一種具有吸引力的濃縮肥料，名叫Aurin。嚴(yán)格的瑞士當(dāng)局為所有作用提供了肥料補(bǔ)貼，因?yàn)锳urin使用絕對安全，而且可以用于所有可食用的作物。/The Vuna technology: Based on many years of research, Eawag has been able to develop a method for the production of a safe concentrated fertiliser from urine[13].Biological treatment stabilises urine and removes the organic matter and the smell. After biological treatment, an activated carbon column remove the remaining pharmaceuticals and hormones excreted via urine. The following distillation concentrates the urine to produce an attractive concentrated fertilizer with the name Aurin. The strict Swiss authorities have provided a fertilizer allowance for all crops, because Aurin is absolutely safe to use, also for all edible crops.For more information, see: https://www.eawag.ch/en/department/eng/projects/aurin-fertilisers-from-urine/