Urban Kidney 都市腎臟

When I take a sip of coffee and a piece of bread, I wouldn’t speculate the aftermath of them - well, at least not every time. The same would happen when I flush the toilet or dump the food leftover in trash can.

當我啜飲咖啡、啃食麵包的時候，我不會去思索它們的去向──至少不會每次都想。同樣的情況發生在我沖馬桶和倒垃圾的時候。

Dr. Hall (I mean Charlie) lectured on the natural nature of cities, which resembled communities in ecosystems or organisms in species. Cities are like human bodies too, taking energy and material from outside and producing waste after consuming them. The only one difference that I can think of now is that cities are partly autotrophic because of the existence of urban forest, but we don’t have algae on our skin to undergo photosynthesis. In fact, this difference doesn’t make a difference. The biomass production in urban neighborhoods is only a tiny fraction (1/200~1/700) of the energy consumed by residence and transportation in the same area, according to a paper in press by Prof. Hall (2011), which means the cities are virtually as dependent as human bodies on foreign energy intake. This sets the common ground for the comparison of cities and ourselves. 

Giant Pumps

Hall博士（我指Charlie）就城市的自然性作了講座。城市就像生態系統中的群落或是物種裡的個體。它們也像人體，從外界攝取能源、物質，消化之後排泄。當前我所能想到的唯一區別在於，由於都市林地的存在，城市是部分自養的，而我們皮膚上卻沒有藻類來進行光合作用。其實這個區別也無傷大雅。根據Hall教授2011年一篇印刷中的論文，都市地區的生物質能產量，相較當地民宅和交通的能耗，只是極小部分（二百分之一到七百分之一），這表明城市幾乎同人體一樣依賴於外部能源攝取。有了這一共同基礎，我們得以比較城市和我們自己。

Primary Clarifier

Referring to my General Biology textbook, I recalled the waste treatment process in kidney, or rather, nephrons. Blood is filtered by glomerulus in Bowman’s capsule, leaving cells and large proteins in the proximal convoluted tubule. Then the filtered blood undergoes the reabsorption process, in which glucose, amino acids and some inorganic ions are taking out. Urine is almost ready to go. Lastly, some waste substances (e.g. penicillin, if taken) are added to the final urine, which will stay in the bladder until excreted. 

翻看生物課本，我憶起了腎臟（更準確地說，腎單位）的廢物處理流程。腎小囊裡的腎小球過濾了血液，將一些細胞和蛋白質大分子留在近曲腎小管中。濾後血液被重吸收，葡萄糖、氨基酸和一些無機離子被分離。尿液初具雛形。最後，一些排泄物（如盤尼西林，若有吞服）被加入到尿液中。膀胱貯存這些尿液，直到主人解手。

Aeration Area

Although it sounds gross, the same process is happening in our cities every single day. Urban dwellers (including industry sections) produce so much wastewater that is way beyond the self-purification ability of rivers. So treating the waste plays a vital role in keeping the cities clean, just as the urinary system in keeping us healthy.

雖然這聽上去很惡心，但相同的事每天都在我們的城市上演。城市住戶（包括工業用戶）產生如此之多的廢水，遠超河流的自淨能力。因此污水處理對於保持城市潔淨極為重要，就如泌尿系統對於保持人體健康一樣。

After the wastewater enters the Metropolitan Syracuse Wastewater Treatment Plant (METRO), it first goes through screening and grit (preprimary treatment), where large solid waste and gravels are filtered out between steel bars and in grit chambers, respectively. Then the primary treatment gets rid of the settled and floating solid waste in huge clarifiers, after which the water is sent to aeration area to be treated with the help of bacteria and iron salt. The second step of the secondary treatment is to leave the water in secondary clarifiers so biosolids are removed and bacteria are recycled. Tertiary treatment consists of the removal of ammonia (using state-of-art technology) and disinfection (using ultraviolet light instead of chlorine). Finally, the discharged water goes into Onondage Lake.

Secondary Clarifier

污水進入大都會雪城廢水處理廠(METRO)後，首先經過過濾和除砂。在此過程（先期處理）中，大型固體廢棄物和砂石分別在鋼條間和除砂室內被濾出。之後的一級處理將沈澱和漂浮在一級沈澱池內的固體垃圾除去；然後廢水被送到暴氣池，在微生物和鐵鹽的作用下做進一步處理。二級處理的第二步是將水滯留在二級沈澱池以移除生物固體和回收細菌。三級處理由除氨（採用先進工藝）和消毒（使用紫外線光照）組成。最終，洩水流入Onondaga湖。

Isn’t it amazing how similar the two systems work? In METRO, oversized waste and smaller solid waste are captured; in kidney, protein molecules and some ions are filtered and reabsorbed, respectively. In METRO, some bacteria and UV light (protons) are added to the waste water; in kidney, stuff like penicillin is added to urine. 

Treated Water Discharge

這兩套系統的運作如此相似豈不神奇？在METRO，大小廢棄物被收回；在腎臟，蛋白質和一些離子分別被濾出和重吸收。在METRO，一些細菌和紫外線（光子）被添加到汙水中；在腎臟中，諸如盤尼西林之類的東西被加入到尿液中。

Similarity of the two systems is just one of my thoughts after visiting METRO. Because this is not a 10-page assignment, I’ll just stop here, and leave the other thoughts in my brain for further meditation.

這兩套系統的相似性僅是我在METRO的觀後感之一。鑒於此非大篇幅作業，我將就此打住，將更多想法留在腦中以備深入思考。

Panorama (sort of)