對(duì)重金屬不超標(biāo)的污泥，可以通過(guò)厭氧消化或者好氧堆肥進(jìn)行土地園林利用，也可以進(jìn)行高附加值資源提取回收。 資料圖片
預(yù)計(jì)到2020年，我國(guó)的污泥產(chǎn)量將達(dá)到6000萬(wàn)噸~9000萬(wàn)噸
國(guó)外傳統(tǒng)的技術(shù)工藝還需要進(jìn)一步研究和提升，才能適合我國(guó)的污泥處理處置
總體道路應(yīng)是污泥和城市有機(jī)質(zhì)廢棄物協(xié)同厭氧消化，實(shí)現(xiàn)規(guī)模化生物質(zhì)燃?xì)饣厥�，生產(chǎn)高品質(zhì)綠化營(yíng)養(yǎng)土
下一代污水處理模式應(yīng)該是基于污染物污泥富集資源回收模式
◆中國(guó)環(huán)境報(bào)見(jiàn)習(xí)記者 張蕊
近些年，隨著我國(guó)不斷興建污水處理廠和配套管網(wǎng)日趨完善，污泥處理成為水務(wù)領(lǐng)域關(guān)注的重點(diǎn)。
由于不同地區(qū)的污泥泥質(zhì)、經(jīng)濟(jì)社會(huì)發(fā)展水平不同，因此在處理方式、處置路線上也面臨著不同的挑戰(zhàn)和選擇。在日前舉行的2014首屆珠三角（東莞）水處理創(chuàng)新交流會(huì)上，同濟(jì)大學(xué)環(huán)境科學(xué)與工程學(xué)院院長(zhǎng)戴曉虎表示，截至2013年，我國(guó)污水處理廠有5300座，污水處理能力達(dá)到1.63億立方米/日，年處理污水量450億立方米，污水處理規(guī)模已經(jīng)接近美國(guó)。從資源化利用角度來(lái)說(shuō)，要從污泥的性質(zhì)和特點(diǎn)考慮處理處置的技術(shù)。下一代污水處理模式，應(yīng)該是基于污染物污泥富集資源回收的模式。
泥質(zhì)決定技術(shù)路線
污泥中60%以上都是蛋白質(zhì)，此外還含有有機(jī)質(zhì)。從資源化利用角度，要從污泥的性質(zhì)和特點(diǎn)考慮處理處置技術(shù)
記者：請(qǐng)問(wèn)我國(guó)污泥產(chǎn)生的狀況如何？
戴曉虎：根據(jù)測(cè)算，我國(guó)每年產(chǎn)生3000萬(wàn)噸~4000萬(wàn)噸含水率在80%左右的污泥。隨著“十三五”的到來(lái)，污泥量還會(huì)增加。預(yù)計(jì)到2020年，我國(guó)的污泥產(chǎn)量將達(dá)到6000萬(wàn)噸~9000萬(wàn)噸。
需要強(qiáng)調(diào)的是，這里所說(shuō)的污泥不包括工業(yè)廢水污泥。如果要加上工業(yè)廢水污泥，我國(guó)的污泥產(chǎn)生量還將更大。
據(jù)測(cè)算，從污水里轉(zhuǎn)入污泥中的COD比例大概是30%~50%，轉(zhuǎn)入污泥中的氮約為20%~30%，磷約為90%。如果它們得不到有效處理處置，那么我國(guó)的節(jié)能減排目標(biāo)將大打折扣。所以不能繼續(xù)重水輕泥的現(xiàn)狀。
記者：和國(guó)外相比，我國(guó)污泥處理處置處于怎樣的水平？
戴曉虎：在污泥處理過(guò)程中，國(guó)際上的通行標(biāo)準(zhǔn)是“四化”，即穩(wěn)定化、減量化、無(wú)害化、資源化。而我國(guó)的現(xiàn)狀是80%甚至90%的污水污泥只是簡(jiǎn)單濃縮脫水。
在穩(wěn)定化方面，我國(guó)污泥普遍沒(méi)有進(jìn)行厭氧處理，好氧堆肥也只是局部性進(jìn)行。污泥處理如果做不到穩(wěn)定化，那么接下來(lái)的無(wú)害化和資源化也就無(wú)從談起。特別值得注意的是有些地方推出的高干脫水，添加大量無(wú)機(jī)材料對(duì)污泥進(jìn)行脫水，其實(shí)根本談不上資源化。
如果污泥沒(méi)有經(jīng)過(guò)穩(wěn)定化處理，其中就會(huì)含有大量有機(jī)物，會(huì)給環(huán)境帶來(lái)嚴(yán)重的二次污染。在國(guó)際上，在前端對(duì)污泥進(jìn)行濃縮或者厭氧好氧處理，然后脫水，接下來(lái)的處置可以在廠區(qū)里或者到廠外去進(jìn)行干化焚燒。
記者：我國(guó)污泥有什么特點(diǎn)？如何針對(duì)這些特點(diǎn)對(duì)污泥加以處理處置？
戴曉虎：圍繞污泥泥質(zhì)，在我國(guó)還有爭(zhēng)論�？傮w上，我國(guó)污泥的有機(jī)質(zhì)含量比較低。和國(guó)外相比，正因?yàn)橛袡C(jī)質(zhì)含量低，所以我國(guó)污泥中總氮、總磷含量也相對(duì)偏低。
另外需要強(qiáng)調(diào)的是，通過(guò)測(cè)算，我們發(fā)現(xiàn)污泥中60%以上都是蛋白質(zhì)，此外還含有有機(jī)質(zhì)。從資源化利用角度來(lái)說(shuō)，要從污泥的性質(zhì)和特點(diǎn)考慮處理處置的技術(shù)。
有觀點(diǎn)認(rèn)為，因?yàn)槲覈?guó)污泥含沙量高、有機(jī)質(zhì)含量低，所以污泥厭氧消化的路線較為合適。對(duì)此，我認(rèn)為，一方面，通過(guò)提升污泥中有機(jī)質(zhì)含量，進(jìn)而才能選擇更好的處理工藝，對(duì)資源加以利用。另一方面，國(guó)外的傳統(tǒng)的技術(shù)工藝在我國(guó)還需要進(jìn)一步研究和提升，才能適合我國(guó)的污泥處理處置。
穩(wěn)定是基礎(chǔ)，厭氧需重視
厭氧消化和干化焚燒組合，可以顯著降低后一個(gè)工藝單元的投資和運(yùn)行費(fèi)用，并可降低污泥含水率和有機(jī)質(zhì)含量；另外一種技術(shù)路線是集中式的城市有機(jī)質(zhì)廢棄物和污泥協(xié)同處置
記者：為什么污泥在干化焚燒前要進(jìn)行厭氧消化？如何提高厭氧消化效率？
戴曉虎：厭氧消化和干化焚燒組合，可以顯著降低后一個(gè)工藝單元的投資和運(yùn)行費(fèi)用，并可降低污泥含水率和有機(jī)質(zhì)含量，有助于實(shí)現(xiàn)能耗平衡。在德國(guó)慕尼黑一個(gè)項(xiàng)目中，污泥經(jīng)過(guò)厭氧消化再干化焚燒，產(chǎn)生的能源基本可以實(shí)現(xiàn)項(xiàng)目能耗的自給自足，彌補(bǔ)厭氧消化的成本，因此國(guó)外有不少城市選擇了這樣的組合工藝。
在污泥資源和能源回收利用方面，沼氣利用是成熟而且經(jīng)過(guò)工程驗(yàn)證的方法。在提升厭氧消化效率方面，上世紀(jì)70年代我們關(guān)注提高固體負(fù)荷或者是提高熱轉(zhuǎn)化率及容積負(fù)荷。
現(xiàn)在我們談厭氧消化，還應(yīng)該包括如何將沼氣中的甲烷進(jìn)行提取分離，這也是提高厭氧消化效率的方法。在2000年以后，第三代厭氧消化池的污泥含固率大于10%，污泥降解率可達(dá)50%。
記者：除了厭氧消化，還有哪些技術(shù)路線可以考慮？
戴曉虎：另外一種技術(shù)路線是集中式的城市有機(jī)質(zhì)廢棄物和污泥的協(xié)同處置。污泥含固率如果在10%，那么厭氧消化的效率也僅有1.5 kgVss/m3d ~2kgVss/m3d。從游離氨、熱值的角度，可以通過(guò)協(xié)同餐廚垃圾等有機(jī)質(zhì)來(lái)提高厭氧消化的效率，大概可以提升到6kgVss/m3d ~10kgVss/m3d。
目前，在高含固污泥/協(xié)同厭氧消化技術(shù)方面也有一些示范工程。主要包括遼寧省大連夏家河污泥集中處理示范工程、浙江省寧海污泥處理示范工程、湖北省襄陽(yáng)污泥處理示范工程、湖南省長(zhǎng)沙污泥集中處理示范工程等。這些示范工程已經(jīng)取得良好效果。
我們認(rèn)為下一代污水處理模式應(yīng)該是基于污染物污泥富集資源回收的模式。第一階段最大化利用生物污泥富集污染物，第二階段回收碳和磷，實(shí)現(xiàn)高效高值利用、氮的高效轉(zhuǎn)化和回收。這一模式的目標(biāo)是能耗輸出、氮和磷回收，反應(yīng)時(shí)間為傳統(tǒng)活性污泥法的1/3~1/4。
珠三角處置污泥有何藥方？
對(duì)重金屬不超標(biāo)的污泥，建議通過(guò)厭氧消化或者好氧堆肥進(jìn)行土地園林利用，也可以進(jìn)行高附加值資源提取回收
記者： 珠三角地區(qū)的污泥現(xiàn)狀是什么？有何特點(diǎn)？
戴曉虎：截至2014年，珠三角擁有城鎮(zhèn)污水處理廠237家，污水處理能力約為0.11億立方米/日，2013年年產(chǎn)污泥突破200萬(wàn)噸（含水率約為80%）。預(yù)計(jì)2020年污泥產(chǎn)量將達(dá)到400萬(wàn)噸~600萬(wàn)噸/年。
珠三角地區(qū)污泥經(jīng)過(guò)脫水后含水率較高，有機(jī)質(zhì)比例偏低，并呈季節(jié)性變化。寄生蟲(chóng)卵、病原微生物等致病物質(zhì)超標(biāo)較普遍。部分污泥存在銅、鉛、鉻等重金屬超標(biāo)現(xiàn)象。污泥中還含有多氯聯(lián)苯等難降解有機(jī)物。
珠三角地區(qū)的污泥處理現(xiàn)在主要以濃縮脫水為主，還有一部分進(jìn)行深度脫水，也有一些污水處理廠對(duì)污泥進(jìn)行水泥窯協(xié)同處置。例如當(dāng)?shù)氐脑奖に鄰S，就對(duì)污泥進(jìn)行水泥窯協(xié)同處置。
我對(duì)珠三角污泥處理處置提幾點(diǎn)建議：圍繞資源化循環(huán)利用，在珠三角地區(qū)尤其是農(nóng)村地區(qū)，重金屬如果超標(biāo)，則可以考慮采用協(xié)同焚燒方式。同時(shí)，熱解氣化技術(shù)還在開(kāi)發(fā)中。而熱能無(wú)機(jī)物也可以作為建材回收利用。
記者： 您怎么評(píng)價(jià)直接干化焚燒處理污泥？有哪些技術(shù)值得關(guān)注？
戴曉虎：我個(gè)人不主張直接采用干化焚燒處理污泥，因?yàn)槲覈?guó)的污泥泥質(zhì)還不穩(wěn)定。如果要單獨(dú)干化焚燒，就必須采用流化床工藝，整個(gè)工藝從資源回收角度來(lái)講做得還不夠。
如果污泥的重金屬含量超標(biāo)嚴(yán)重，也可以采用干化焚燒的方式對(duì)污泥進(jìn)行處理。而熱解技術(shù)和協(xié)同技術(shù)可能會(huì)有市場(chǎng)空間。對(duì)重金屬不超標(biāo)的污泥，我強(qiáng)烈建議通過(guò)厭氧消化或者好氧堆肥進(jìn)行土地園林利用，也可以進(jìn)行高附加值資源提取回收。
在高附加值資源提取回收方面，無(wú)論是提蛋白、甲烷回收等方法都可以采用。
總體道路還應(yīng)該是污泥和城市有機(jī)質(zhì)廢棄物協(xié)同厭氧消化，實(shí)現(xiàn)規(guī)模化生物質(zhì)燃?xì)饣厥�，生產(chǎn)高品質(zhì)綠化營(yíng)養(yǎng)土。這些模式在我國(guó)山東省、福建省廈門(mén)市等地都有實(shí)踐，主要處理工藝就是將餐廚、菜市場(chǎng)垃圾和污泥協(xié)同處置。
污泥處理處置還有哪些挑戰(zhàn)？
需要技術(shù)綜合集成示范；提升污泥品質(zhì)并進(jìn)行合理的風(fēng)險(xiǎn)評(píng)估；污泥處理處置經(jīng)費(fèi)需要落實(shí)
記者： 現(xiàn)在我國(guó)污泥處理處置還需要解決哪些瓶頸問(wèn)題？為何土地利用的路線沒(méi)有得到重視？您對(duì)此有何建議？
戴曉虎：現(xiàn)在污泥處置的瓶頸問(wèn)題主要包括：?jiǎn)我患夹g(shù)很多并相對(duì)成熟，但是需要技術(shù)綜合集成示范，研究全流程綜合解決方案。目前厭氧、好氧污泥土地利用受到限制，一方面主要是由于我國(guó)目前污泥品質(zhì)還不高，另一方面，污泥土地利用的風(fēng)險(xiǎn)相對(duì)被夸大。
同時(shí)，國(guó)內(nèi)還存在強(qiáng)制的污泥“穩(wěn)定化”要求。相關(guān)部門(mén)應(yīng)該就此進(jìn)行協(xié)調(diào)，提升污泥品質(zhì)并進(jìn)行合理的風(fēng)險(xiǎn)評(píng)估。
此外，污泥處理處置經(jīng)費(fèi)需要落實(shí)。建議可以借用德國(guó)做法，在后端根據(jù)出產(chǎn)的沼氣量進(jìn)行補(bǔ)貼。同時(shí)，污泥處理處置費(fèi)用必須融入污水處理費(fèi)中，污泥、污水處理分不開(kāi)。
此外，技術(shù)開(kāi)發(fā)和市場(chǎng)的有效結(jié)合也很重要，需要開(kāi)發(fā)全產(chǎn)業(yè)鏈可持續(xù)發(fā)展的商業(yè)模式。而我們也可以斷定，我國(guó)污泥處理機(jī)遇和挑戰(zhàn)共存，思維理念轉(zhuǎn)變和前瞻性創(chuàng)新需要勇氣和擔(dān)當(dāng)。同時(shí)巨大的市場(chǎng)和需求、大量研發(fā)經(jīng)費(fèi)的投入，定會(huì)引領(lǐng)未來(lái)污泥處理處置資源化技術(shù)的發(fā)展。
污水處理新模式：污染物污泥富集資源回收模式
Not excessive sludge of heavy metals, can land garden use by anaerobic digestion or aerobic composting, can also be of high value-added resource extraction recovery. Profile picture
2020, China's sludge production will reach 60 million tons - 90 million tons
Foreign traditional craft techniques and further research is needed to improve in order for our sludge treatment and disposal
Overall sludge and urban roads should be synergistic anaerobic digestion of organic matter waste, chemical and biological substances to achieve scale gas recovery, production of high-quality green nutritive soil
The next generation of wastewater treatment sludge model should be based on contaminant enrichment resource recovery mode
◆ China Environment News trainee reporter Zhang Rui
In recent years, as China continues to build a sewage treatment plant and associated pipeline network maturing, sludge treatment has become the focus of attention in the field of water.
Due to muddy sludge in different regions, different levels of economic and social development, so the handling, disposal routes are also faced with different challenges and choices. At the recent 2014 inaugural Pearl River Delta (Dongguan) Water Innovation conference, Dean of College of Environmental Science and Engineering, Tongji University Daixiao Hu said that as of 2013, China's sewage treatment plant has a 5300 sewage treatment capacity of 163 million cubic meters / day, the annual amount of 45 billion cubic meters of sewage treatment, sewage treatment capacity has been close to the United States. From the perspective of resource utilization, from a consideration of the nature and characteristics of sludge treatment and disposal technologies. The next generation of wastewater treatment model, it should be enriched sludge recycling of pollutants based mode.
Argillaceous decision technology roadmap
More than 60% of sludge are protein, also contains organic matter. From the perspective of resource utilization, the nature and characteristics of the sludge from the treatment and disposal technologies considered
Reporter: What is the status of sludge how?
Dai Xiaohu: According to estimates, our country produces 30 million tons - 40 million tons moisture content of about 80% of sludge per year. With the advent of "Thirteen Five", the sludge volume will increase. 2020, China's sludge production will reach 60 million tons to 9,000 tons.
It should be stressed that the sludge is not mentioned here, including industrial wastewater sludge. If you want to add industrial wastewater sludge, the amount of sludge produced will be greater.
It is estimated that the proportion of COD transferred from the sewage sludge in about 30% to 50% of nitrogen into the sludge is about 20% to 30%, about 90% of phosphorus. If they are not effective treatment and disposal, so our energy reduction targets will be greatly reduced. So the status quo can not continue heavy water light mud.
Reporter: and abroad compared to sludge treatment and disposal of at what level?
Dai Xiaohu: In the sludge treatment process, the prevailing international standards is the "four modernizations", ie stabilization, reduction, sound, resource. The current situation in China is 80% or even 90% of sewage sludge dewatering simply.
In terms of stabilization, our universal no anaerobic treatment of sludge, aerobic composting is only performed locally. If you can not stabilized sludge treatment, then the next harmless and resources does not arise. Of particular note is the introduction of senior cadres in some places dehydration, adding a large number of inorganic materials for sludge dewatering, in fact, not to mention resources.
If you have not been stabilized sludge treatment, which will contain a lot of organic matter, will give the environment a serious secondary pollution. In the international arena, in front of the concentrated sludge or anaerobic and aerobic treatment, then dehydrated, then disposal in the plant or outside in dry incineration plant go.
Reporter: What are the characteristics of the sludge? How to deal with these characteristics for the disposal of sludge?
Dai Xiaohu: around muddy sludge in the country as well as controversy. Overall, the organic content of the sludge is relatively low. And abroad compared because of low organic matter content, so the total nitrogen, total phosphorus content of the sludge is relatively low.
Also needs to be emphasized is that by calculation, we found that more than 60% of sludge are protein, also contains organic matter. From the perspective of resource utilization, from a consideration of the nature and characteristics of sludge treatment and disposal technologies.
The idea that, because of the high sediment sludge, low organic matter content, so the anaerobic digestion of the route is more appropriate. In this regard, I think, on the one hand, by increasing the organic matter content of the sludge, and then to choose a better treatment process, the resource to be utilized. On the other hand, the traditional craft of foreign technology requires further research and improvements in our country, in order to fit our sludge treatment and disposal.
Stability is the basis, anaerobic need attention
Dry anaerobic digestion and incineration combination can significantly reduce investment and operating costs after a process unit, and reduce the moisture content of the sludge and organic content; another technology route is centralized urban organic waste and sludge together disposal
Reporter: Why sludge before drying and incineration to anaerobic digestion? How to improve the efficiency of the anaerobic digestion?
Dai Xiaohu: dry anaerobic digestion and incineration combination, can significantly reduce the capital and operating costs of a process unit, and reduce the moisture content of the sludge and organic matter content, help to achieve energy balance. In Munich, Germany, a project, do it again sludge incineration through anaerobic digestion, energy generated by the project can be basically achieved self-sufficiency in energy consumption to make up for the anaerobic digestion of cost, so there are many cities abroad chose this combination process .
Sludge recycling of resources and energy, the biogas utilization is mature and proven through engineering methods. In improving the efficiency of anaerobic digestion, 1970s solid load or increase our concern is to improve the thermal conversion rate and volume load.
Now we are talking about anaerobic digestion, but also should include how to extract methane gas separation, which is to improve the efficiency of the anaerobic digestion method. Later in 2000, the third generation of anaerobic digester sludge solids greater than 10%, the sludge degradation rate of 50%.
Reporter: In addition to anaerobic digestion, what technology roadmap could be considered?
Dai Xiaohu: Another technique centralized disposal route is coordinated urban organic waste and sewage sludge. If the sludge solid content of 10%, then the efficiency of the anaerobic digestion is also just 1.5 kgVss / m3d ~ 2kgVss / m3d. From the perspective of free ammonia, calorific value, can improve the efficiency of the anaerobic digestion of food waste and other organic matter through a collaborative, probably can be raised to 6kgVss / m3d ~ 10kgVss / m3d.
Currently, high solids sludge / synergistic anaerobic digestion technology, there are some aspects of the demonstration project. Including Liaoning Province, Dalian Xiajiahe centralized sludge treatment demonstration project, Ninghai sludge treatment demonstration project, sludge treatment demonstration project Xiangyang, Hubei and Hunan Changsha centralized sludge treatment demonstration projects. These demonstration projects have achieved good results.
We believe the next generation of wastewater treatment sludge model should be based on contaminant enrichment resource recovery mode. The first stage to maximize the use of biological sludge accumulation of pollutants, the second phase of the recovery of carbon and phosphorus to achieve efficient use of high-value, high-efficiency conversion of nitrogen and recovery. The goal of this model is that energy output, nitrogen and phosphorus recovery, the reaction time is conventional activated sludge process 1/3 to 1/4.
What sludge disposal PRD prescription?
For heavy metal sludge is not exceeded recommended by anaerobic digestion or aerobic composting garden land use, also can be high value-added resource extraction recovery
Reporter: What is the status quo sludge PRD is? What are the characteristics?
Dai Xiaohu: As of 2014, the PRD has 237 municipal wastewater treatment plants, sewage treatment capacity of approximately 011 million cubic meters / day in 2013 to break 2 million tons annual output of sludge (water content of about 80%). Sludge production in 2020 is expected to reach 4 million tons to 600 million tons / year.
Pearl River Delta region after dewatering sludge moisture content is high, the low proportion of organic matter, and showed seasonal variation. Parasite eggs, pathogenic microorganisms and other pathogenic substances exceeding more common. Part sludge presence of copper, lead, chromium and other heavy metals exceeded phenomenon. Sludge also contains PCBs and other refractory organics.
Sludge Treatment PRD is now mainly concentrated mainly dehydration, as well as part of deep dehydration, there are some sewage treatment plant sludge disposal of cement kiln collaboration. For example, the local Fort cement plants, cement kilns on collaborative sludge disposal.
I PRD sludge disposal a few suggestions: focus on resource recycling, in the Pearl River Delta region, especially in rural areas, heavy metals, if exceeded, you might consider using collaborative incineration. Meanwhile, pyrolysis and gasification technology is still in development. And the thermal energy can be used as the inorganic building materials recycling.
Reporter: how do you evaluate the direct drying sludge incineration? What are the technical cause for concern?
Dai Xiaohu: I personally do not advocate the direct use of drying sludge incineration, because our country is not stable muddy sludge. If you want to separate drying and incineration, you must use the fluidized bed process, the entire process of recovering from a resource point of view in terms of not doing enough.
If the heavy metal content of sludge serious, can also be used for drying and incineration of sludge treatment methods. The pyrolysis technology and collaborative technologies may be market space. Not excessive sludge of heavy metals, and I strongly recommend via anaerobic digestion or aerobic composting garden land use, high value-added resources can also be extracted for recycling.
In the resource extraction recovery of high-value, whether the protein is to provide the methane recovery and other methods can be used.
Overall roads should also be coordinated waste sludge and municipal anaerobic digestion of organic matter, chemical and biological substances to achieve scale gas recovery, production of high-quality green nutritive soil. These patterns of Shandong Province, Xiamen City, Fujian Province and other places have practice, the main treatment process is to dining kitchen, vegetable market waste and sludge disposal collaboration.
Sludge treatment and disposal as well as what are the challenges?
Requires comprehensive integration technology demonstration; improve sludge quality and reasonable risk assessment; sludge treatment and disposal funds needed to implement
Reporter: Now sludge treatment and disposal of bottlenecks which need to be addressed? Why route of land use are not taken seriously? What do you recommend?
Dai Xiaohu: now the bottleneck problem of sludge disposal include: a single lot and relatively mature technology, but requires comprehensive integration technology demonstration study the whole process of integrated solutions. Currently anaerobic, aerobic sludge land-use restrictions, on the one hand is mainly due to China's current sludge quality is not high, on the other hand, the relative risk of sludge land use have been exaggerated.
Meanwhile, there are mandatory domestic sludge "stabilization" requirement. In this connection the relevant departments should coordinate and enhance the quality of sludge and reasonable risk assessment.
In addition, sludge treatment and disposal funds need to be implemented. German practice recommendations can be borrowed at the back end subsidies based on the amount of biogas produced. Meanwhile, sludge treatment and disposal costs must be integrated into the sewage treatment fee, sludge, sewage treatment inseparable.
In addition, the effective integration of technology development and market is also very important, the need to develop business models for sustainable development of the whole industry chain. And we can conclude that our sludge treatment opportunities and challenges coexist, innovative and forward-thinking concept of change requires courage and play. Meanwhile a huge market and demand, putting in a lot of R & D funding, will lead the future development of sludge treatment and disposal technology resources.
Sewage new model: the enrichment of pollutants sludge recycling mode
September 16, 2014 Source: China News NetworkNot excessive sludge of heavy metals, can land garden use by anaerobic digestion or aerobic composting, can also be of high value-added resource extraction recovery. Profile picture
2020, China's sludge production will reach 60 million tons - 90 million tons
Foreign traditional craft techniques and further research is needed to improve in order for our sludge treatment and disposal
Overall sludge and urban roads should be synergistic anaerobic digestion of organic matter waste, chemical and biological substances to achieve scale gas recovery, production of high-quality green nutritive soil
The next generation of wastewater treatment sludge model should be based on contaminant enrichment resource recovery mode
◆ China Environment News trainee reporter Zhang Rui
In recent years, as China continues to build a sewage treatment plant and associated pipeline network maturing, sludge treatment has become the focus of attention in the field of water.
Due to muddy sludge in different regions, different levels of economic and social development, so the handling, disposal routes are also faced with different challenges and choices. At the recent 2014 inaugural Pearl River Delta (Dongguan) Water Innovation conference, Dean of College of Environmental Science and Engineering, Tongji University Daixiao Hu said that as of 2013, China's sewage treatment plant has a 5300 sewage treatment capacity of 163 million cubic meters / day, the annual amount of 45 billion cubic meters of sewage treatment, sewage treatment capacity has been close to the United States. From the perspective of resource utilization, from a consideration of the nature and characteristics of sludge treatment and disposal technologies. The next generation of wastewater treatment model, it should be enriched sludge recycling of pollutants based mode.
Argillaceous decision technology roadmap
More than 60% of sludge are protein, also contains organic matter. From the perspective of resource utilization, the nature and characteristics of the sludge from the treatment and disposal technologies considered
Reporter: What is the status of sludge how?
Dai Xiaohu: According to estimates, our country produces 30 million tons - 40 million tons moisture content of about 80% of sludge per year. With the advent of "Thirteen Five", the sludge volume will increase. 2020, China's sludge production will reach 60 million tons to 9,000 tons.
It should be stressed that the sludge is not mentioned here, including industrial wastewater sludge. If you want to add industrial wastewater sludge, the amount of sludge produced will be greater.
It is estimated that the proportion of COD transferred from the sewage sludge in about 30% to 50% of nitrogen into the sludge is about 20% to 30%, about 90% of phosphorus. If they are not effective treatment and disposal, so our energy reduction targets will be greatly reduced. So the status quo can not continue heavy water light mud.
Reporter: and abroad compared to sludge treatment and disposal of at what level?
Dai Xiaohu: In the sludge treatment process, the prevailing international standards is the "four modernizations", ie stabilization, reduction, sound, resource. The current situation in China is 80% or even 90% of sewage sludge dewatering simply.
In terms of stabilization, our universal no anaerobic treatment of sludge, aerobic composting is only performed locally. If you can not stabilized sludge treatment, then the next harmless and resources does not arise. Of particular note is the introduction of senior cadres in some places dehydration, adding a large number of inorganic materials for sludge dewatering, in fact, not to mention resources.
If you have not been stabilized sludge treatment, which will contain a lot of organic matter, will give the environment a serious secondary pollution. In the international arena, in front of the concentrated sludge or anaerobic and aerobic treatment, then dehydrated, then disposal in the plant or outside in dry incineration plant go.
Reporter: What are the characteristics of the sludge? How to deal with these characteristics for the disposal of sludge?
Dai Xiaohu: around muddy sludge in the country as well as controversy. Overall, the organic content of the sludge is relatively low. And abroad compared because of low organic matter content, so the total nitrogen, total phosphorus content of the sludge is relatively low.
Also needs to be emphasized is that by calculation, we found that more than 60% of sludge are protein, also contains organic matter. From the perspective of resource utilization, from a consideration of the nature and characteristics of sludge treatment and disposal technologies.
The idea that, because of the high sediment sludge, low organic matter content, so the anaerobic digestion of the route is more appropriate. In this regard, I think, on the one hand, by increasing the organic matter content of the sludge, and then to choose a better treatment process, the resource to be utilized. On the other hand, the traditional craft of foreign technology requires further research and improvements in our country, in order to fit our sludge treatment and disposal.
Stability is the basis, anaerobic need attention
Dry anaerobic digestion and incineration combination can significantly reduce investment and operating costs after a process unit, and reduce the moisture content of the sludge and organic content; another technology route is centralized urban organic waste and sludge together disposal
Reporter: Why sludge before drying and incineration to anaerobic digestion? How to improve the efficiency of the anaerobic digestion?
Dai Xiaohu: dry anaerobic digestion and incineration combination, can significantly reduce the capital and operating costs of a process unit, and reduce the moisture content of the sludge and organic matter content, help to achieve energy balance. In Munich, Germany, a project, do it again sludge incineration through anaerobic digestion, energy generated by the project can be basically achieved self-sufficiency in energy consumption to make up for the anaerobic digestion of cost, so there are many cities abroad chose this combination process .
Sludge recycling of resources and energy, the biogas utilization is mature and proven through engineering methods. In improving the efficiency of anaerobic digestion, 1970s solid load or increase our concern is to improve the thermal conversion rate and volume load.
Now we are talking about anaerobic digestion, but also should include how to extract methane gas separation, which is to improve the efficiency of the anaerobic digestion method. Later in 2000, the third generation of anaerobic digester sludge solids greater than 10%, the sludge degradation rate of 50%.
Reporter: In addition to anaerobic digestion, what technology roadmap could be considered?
Dai Xiaohu: Another technique centralized disposal route is coordinated urban organic waste and sewage sludge. If the sludge solid content of 10%, then the efficiency of the anaerobic digestion is also just 1.5 kgVss / m3d ~ 2kgVss / m3d. From the perspective of free ammonia, calorific value, can improve the efficiency of the anaerobic digestion of food waste and other organic matter through a collaborative, probably can be raised to 6kgVss / m3d ~ 10kgVss / m3d.
Currently, high solids sludge / synergistic anaerobic digestion technology, there are some aspects of the demonstration project. Including Liaoning Province, Dalian Xiajiahe centralized sludge treatment demonstration project, Ninghai sludge treatment demonstration project, sludge treatment demonstration project Xiangyang, Hubei and Hunan Changsha centralized sludge treatment demonstration projects. These demonstration projects have achieved good results.
We believe the next generation of wastewater treatment sludge model should be based on contaminant enrichment resource recovery mode. The first stage to maximize the use of biological sludge accumulation of pollutants, the second phase of the recovery of carbon and phosphorus to achieve efficient use of high-value, high-efficiency conversion of nitrogen and recovery. The goal of this model is that energy output, nitrogen and phosphorus recovery, the reaction time is conventional activated sludge process 1/3 to 1/4.
What sludge disposal PRD prescription?
For heavy metal sludge is not exceeded recommended by anaerobic digestion or aerobic composting garden land use, also can be high value-added resource extraction recovery
Reporter: What is the status quo sludge PRD is? What are the characteristics?
Dai Xiaohu: As of 2014, the PRD has 237 municipal wastewater treatment plants, sewage treatment capacity of approximately 011 million cubic meters / day in 2013 to break 2 million tons annual output of sludge (water content of about 80%). Sludge production in 2020 is expected to reach 4 million tons to 600 million tons / year.
Pearl River Delta region after dewatering sludge moisture content is high, the low proportion of organic matter, and showed seasonal variation. Parasite eggs, pathogenic microorganisms and other pathogenic substances exceeding more common. Part sludge presence of copper, lead, chromium and other heavy metals exceeded phenomenon. Sludge also contains PCBs and other refractory organics.
Sludge Treatment PRD is now mainly concentrated mainly dehydration, as well as part of deep dehydration, there are some sewage treatment plant sludge disposal of cement kiln collaboration. For example, the local Fort cement plants, cement kilns on collaborative sludge disposal.
I PRD sludge disposal a few suggestions: focus on resource recycling, in the Pearl River Delta region, especially in rural areas, heavy metals, if exceeded, you might consider using collaborative incineration. Meanwhile, pyrolysis and gasification technology is still in development. And the thermal energy can be used as the inorganic building materials recycling.
Reporter: how do you evaluate the direct drying sludge incineration? What are the technical cause for concern?
Dai Xiaohu: I personally do not advocate the direct use of drying sludge incineration, because our country is not stable muddy sludge. If you want to separate drying and incineration, you must use the fluidized bed process, the entire process of recovering from a resource point of view in terms of not doing enough.
If the heavy metal content of sludge serious, can also be used for drying and incineration of sludge treatment methods. The pyrolysis technology and collaborative technologies may be market space. Not excessive sludge of heavy metals, and I strongly recommend via anaerobic digestion or aerobic composting garden land use, high value-added resources can also be extracted for recycling.
In the resource extraction recovery of high-value, whether the protein is to provide the methane recovery and other methods can be used.
Overall roads should also be coordinated waste sludge and municipal anaerobic digestion of organic matter, chemical and biological substances to achieve scale gas recovery, production of high-quality green nutritive soil. These patterns of Shandong Province, Xiamen City, Fujian Province and other places have practice, the main treatment process is to dining kitchen, vegetable market waste and sludge disposal collaboration.
Sludge treatment and disposal as well as what are the challenges?
Requires comprehensive integration technology demonstration; improve sludge quality and reasonable risk assessment; sludge treatment and disposal funds needed to implement
Reporter: Now sludge treatment and disposal of bottlenecks which need to be addressed? Why route of land use are not taken seriously? What do you recommend?
Dai Xiaohu: now the bottleneck problem of sludge disposal include: a single lot and relatively mature technology, but requires comprehensive integration technology demonstration study the whole process of integrated solutions. Currently anaerobic, aerobic sludge land-use restrictions, on the one hand is mainly due to China's current sludge quality is not high, on the other hand, the relative risk of sludge land use have been exaggerated.
Meanwhile, there are mandatory domestic sludge "stabilization" requirement. In this connection the relevant departments should coordinate and enhance the quality of sludge and reasonable risk assessment.
In addition, sludge treatment and disposal funds need to be implemented. German practice recommendations can be borrowed at the back end subsidies based on the amount of biogas produced. Meanwhile, sludge treatment and disposal costs must be integrated into the sewage treatment fee, sludge, sewage treatment inseparable.
In addition, the effective integration of technology development and market is also very important, the need to develop business models for sustainable development of the whole industry chain. And we can conclude that our sludge treatment opportunities and challenges coexist, innovative and forward-thinking concept of change requires courage and play. Meanwhile a huge market and demand, putting in a lot of R & D funding, will lead the future development of sludge treatment and disposal technology resources.
Sewage new model: the enrichment of pollutants sludge recycling mode
September 16, 2014 Source: China News Network
