OPINION: OVERCOMING HURDLES TO RESOURCE RECOVERY FROM WASTEWATER
/ a6 f- D6 m2 h专家最新观点:克服废水资源回收的障碍
* N" k5 Z+ Z4 h1 H# a+ qMark van Loosdrecht.) i1 f. d( F' M* |" }9 F! c
8 X, J; V8 p+ x# g- V; MMark教授,最近Aquatech网站发表了Mark教授关于对污水中能源及资源回收的观点,笔者注意到,这些观点是近几年Mark教授的一些新表述,有些观点可能与目前国内外的一些主流观点或者部分实践“不太一致”。如通过餐厨或food waste的输入厌氧消化的“协同厌氧消化”的做法,Mark认为:“It should also be noted that it is misleading to import food waste to become a net energy supplier WWTP”. “需要强调的是,厌氧消化系统中引入厨余垃圾使污水处理厂变成能源工厂不过是一种误导。”4 Z) _1 i3 y8 j
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此外,Mark教授还分享了关于污水中资源回收、热能回收等方面一些观点,如资源回收的内驱力,技术障碍是容易克服的,目前主要的障碍在于市场和社会层面,这种驱动力更多情况下是来自水务自身,而不是来自于外部市场的驱动。& j( @" m. q3 R7 G
* k. S+ A6 ^0 U& q9 U. ^具体内容,详见下面:
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A technology push without a market pull
d/ V% [7 a' Z. Q" eEven though the term ‘wastewater’ includes the word ‘waste’, it is not, in fact, wasted water. Instead, it is water used to flush waste out of individual houses towards a treatment facility.
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% C' v3 L: ~3 g6 L4 QBy shifting to a circular economy, including integrated wastewater treatment, it means that as well as the water, waste should also be recovered.
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While water recovery is well established, naturally (through the cycle of rain – rivers – oceans – clouds – rain) or though engineered systems in water-scarce areas, the recovery of waste, however, is much more complicated.! T' q2 E: w" Q& B2 R
; t; Q0 E6 z9 B9 q- VOne of the main reasons is because it requires a broader interaction with sectors beyond water to integrate the recovered products into a circular economy.; D' F9 z! X9 u# I$ E2 t
2 l y& c2 w c) q6 l' kTo date, developments can largely be described as a technology push, without a market pull.”1 t9 s% q2 e$ O K0 E2 I
到目前为止,发展在很大程度上可以说是技术推动,而不是市场拉动。3 b( N8 j' V% z4 ~0 u$ n
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5 x+ K7 B, \) B& d, `2 YSo where do the challenges lie? To date, developments can broadly be described as a technology push, without a market pull. The waste in the wastewater can be recovered as energy, or as a material resource with the two options offering different benefits.
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! @+ v8 R) ]3 V: H% TEnergy self-sufficiency7 `7 I4 v7 u, Z3 }1 V! ~
In both cases reference above, internal drivers often push water utilities to go down the recovery technology route. X9 z1 \* V) g+ k& g& e
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This usually results in the building of a sludge digester to recover the biogas, with the critical decision based on minimising excess sludge production.
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Recovering biogas to drive a self-sufficient wastewater treatment plant (WWPT) is good practice, but unfortunately, this will unlikely result in energy-producing wastewater treatment plants. Indeed, if the self-sufficiency allows water utilities to become independent from their energy suppliers, then there is, of course, a significant economic advantage.: e& q+ N8 ^3 f
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It should also be noted that it is misleading to import food waste to become a net energy supplier WWTP.
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The food waste import is, in fact, an energy import to the WWTP, and as a result, should be accounted as such. From an energy point of view, the recovery of heat from treated wastewater is more interesting. Therefore, it is essential to focus more on heat integration instead of paying most of the attention towards biogas generation.' z8 h- X5 g* [ Y2 Z$ |$ K& A
0 `; ?. v( S' W% \2 [Internal drivers for material recovery8 c; H& C7 d# @6 g: }' b4 m0 x
Technological hurdles for recovery processes, in general, can be relatively easily overcome, and, as a result, there are many examples of products being recovered: phosphate, nitrogen, bioplastic (PHA), biopolymers (e.g. Kaumera®), proteins, cellulose, lipids. As a result, materials recovery remains mostly in its infancy.
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4 l6 E9 r/ _% q& T$ g7 |& K; ?' C1 ?: aMany socio-economic hurdles are more challenging to overcome. Most of the current recovery processes (especially those for phosphate and cellulose) are implemented based on internal drivers of the water utility, instead of a market push.
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“While these internal drivers are certainly helpful, this often results in resources not finding a market place.”" d4 d; E4 o( p
虽然这些内部驱动因素确实有帮助,但这往往导致资源找不到市场。4 Z6 o+ J8 _6 r* K! D
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) l2 y# [ X& H) rWhile these internal drivers are undoubtedly helpful, this often results in resources not finding a market place. Utilities can stop being active when the recovered "product" reaches the gate of the treatment plant, and the public communication goals have been achieved.
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Building a water-smart economy: I, [& }8 c+ a& [% \$ t1 `. _' p
Water reuse will drive the integration of water utilities in a circular economy. Products can support this development, but there is a strong integration needed between engineering, economic and societal disciplines to design viable systems. $ V! l) i* t2 O' u# _% }
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The EU Horizon 2020 program “Building a water-smart economy and society” recognises the need to make alternative water resources of various qualities available.
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These should be appropriate for different functions and multiple users, and to better exploit water resources and all the valuable substances that could be obtained through the wastewater treatment and reuse process.
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( p1 \ X1 F. a/ l' C5 k3 z1 D4 SAs a result, five large scale demonstration programs have been financed under this scheme, and the leadership of the Netherlands is shown by three of these programmes, coordinated by Dutch institutes KWR Water Research Institute and TU-Delft., A5 {# i. e( K. b, l% S
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