오줌, 오줌으로 도시 폐수를 정화, Pee, pee to clean up urban wastewater

1980~1990년대 남자 중고등학교 화장실에는 소변 수거통이 따로 있었다. 오줌 속에 있는 요소를 이용해 비료를 추출하기 위해서였다. 옛날이야기 같지만, 최근 환경 보호를 위해 소변을 활용해 비료 원료를 추출하는 기술이 다시 주목받고 있다.

이런 가운데, 중국 헤이난대 물리·전자공학부, 칭다오대 물리학부, 미국 스탠퍼드대 기계공학과 공동 연구팀은 소변에서 농작물 비료뿐만 아니라 도시 폐수를 정화할 수 있는 물질을 추출할 수 있는 방법을 새로 개발했다고 밝혔다. 이 연구 결과는 화학 분야 국제 학술지 ‘네이처 촉매’에 실렸다.


오줌에는 비료의 핵심 성분인 질소가 풍부한 요소라는 화합물이 포함돼 있다. 이 때문에 소변은 농업 분야에서 활용도가 높아 ‘액체 황금’이라고 불리기도 하지만, 실제로는 폐기물로 처리되는 경우가 훨씬 많다. 그래서, 폐수 처리 공학 분야에서는 방대한 양의 소변을 저장하고 요소를 유용한 화학 물질로 전환하는 메커니즘 개발이 주요 관심사로 떠오르고 있다.

연구팀은 전기화학 반응을 이용해 복잡한 처리 단계를 거치지 않고 폐수와 소변에서 거의 100% 순수한 요소의 고체 유도체 ‘퍼카바마이드’(percarbamide)로 변환시키는 데 성공했다. 연구팀은 탄소 기반 전극을 촉매로 사용하고 대기 중 산소를 사용해 기존 반응보다 낮은 온도와 압력에서 퍼카바마이드를 생성했다. 이렇게 추출해 수집된 퍼카바마이드는 수처리, 소독, 작물 성장 개선 등 다양한 분야에서 활용될 수 있다.

이번에 개발된 메커니즘은 사람과 포유류 소변 모두에 적용할 수 있으며, 다른 방법보다 더 간단하고 저렴하며 순도가 높은 제품을 생산할 수 있다는 장점이 있다. 연구팀은 경제적 분석을 통해 하루 1t의 퍼카바마이드를 생산하기 위해서는 100㎡의 공간과 6382가구나 소 3800마리의 소변을 수집하면 되는 것으로 조사돼 비용 효율성도 높은 것으로 확인됐다.

 

 

 

 

In the 1980s and 1990s, men's middle and high school toilets had separate urine collectors. This was done to extract fertilizer using urea in urine. This seems like an old story, but recently, for environmental protection, a technology that extracts fertilizer raw materials using urine is attracting attention again.

Meanwhile, a joint research team led by Hainan University's Department of Physics and Electronics, Qingdao University's Department of Physics and Mechanical Engineering and Stanford University has developed a new method to extract substances that can purify urban wastewater as well as crop fertilizers from urine. The findings were published in Nature Catalyst, an international journal on chemistry.


Urine contains a compound called nitrogen-rich urea, a key component of fertilizer. Due to its high utilization in agriculture, urine is sometimes referred to as 'liquid gold', but it is much more often treated as waste. Therefore, the development of mechanisms that store vast amounts of urine and convert urea into useful chemicals is emerging as a major concern in the field of wastewater treatment engineering.

The research team successfully converted nearly 100 percent pure urea solid derivative "percarbamide" from wastewater and urine without going through complicated treatment steps using electrochemical reactions. Using carbon-based electrodes as catalysts and oxygen in the atmosphere, the research team produced percarbamide at lower temperatures and pressures than conventional reactions. Percarbamide extracted and collected in this way can be used in various fields such as water treatment, disinfection, and crop growth improvement.

The mechanism developed this time can be applied to both human and mammal urine, and has the advantage of producing products that are simpler, cheaper and higher in purity than other methods. The research team found that in order to produce 1 ton of percabamide per day through economic analysis, it is necessary to collect 100㎡ of space and 6,382 households or 3,800 cows, which is also cost-effective.