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1、【精品文档】如有侵权，请联系网站删除，仅供学习与交流综合厌氧处理乳品工业废水和污泥翻译.精品文档.综合厌氧处理乳品工业废水和污泥摘要：人们研究了一个替代的乳品污水处理系统的性能参数，该系统包括两个厌氧污泥反应器，均安排向上流动，内部脂肪分离浮选，外部板定居和浮动材料沼气池。反应器最初接种高负荷的絮状和粒状污泥。使用负荷率最高达5.5kgCOD/m3.d ，水力停留时间17小时，发现反应器仍能稳定去除90%的COD。长链脂肪酸的测定使用抑制棕榈酸脂，然而现在发现不仅取决于棕榈酸酯的浓度，而且还跟棕榈酸酯的生物量浓度比有关。导言生产产品的不同，以及在生产以奶制品为原料的产品使用的设备和工艺的不同，
2、不同的工厂污水特征可能大不相同。因此，每一个种情况，都必须单独考虑，以确保适宜的处理方案（德米雷尔等al.2005 ） 。尽管如此，由于生产过程中奶类或以奶类为原料的产品泄漏，一些成分有规律地在乳品工业废水中检测出来：乳糖，血脂，酪蛋白和其他蛋白质。由甘油三酯组成的脂质，主要出现在乳液最初的均质过程。此外，废水将根据在任何的进程中所使用的化学洗涤剂呈现酸性或碱性。 在处理乳品废水以及其他复杂的废水中，上流式厌氧污泥反应器取得的效果很小，这是因为相当数量的有机物质水解率或降低率过于低，而通常导致污泥床内的卷吸或吸附。其结果只是稀释生物量，伪装了传质性能和损害污泥沉降能力。污泥活性因此降低，污泥可
3、能从反应器中流出（赛义德1984 ;赛义德1987年; Rinzema 1993年;胡等al.1998 ） 。 一批研究选用不适应降解脂肪的生物且在基底负荷高达每克VSS中既有脂肪12.6克（Petruy 拉丁格1997年），这些研究表明了奶制品脂肪乳剂的快速吸附和显著退化。2000年维达尔等报告说，脂肪丰富的乳品废水的生物降解率局限于脂肪水解。他们分批进行检测不适应的生物。然而，使用适合的载体和与底物适应的微生物，水解可能无法成为总处理过程的速率限制因素。不受限于水解，总处理率可能会受限于由于长链脂肪酸吸附污泥而降低的质量传输速率（佩雷拉等al.2003 ;佩雷拉等al.2004 ），或者是
4、长链脂肪酸对产甲烷物种的抑制作用（佩雷拉等al.2005 ;胡等al.1996 ）。根据1998年胡等人的研究报告，在上流式厌氧污泥反应器中由于长链脂肪酸的吸附而产生的污泥上浮，可能会比那些产生抑制作用的出现在更低的长链脂肪酸的浓度。为了研究上流式厌氧污泥床反应器前阶段的脂肪吸附和长链脂肪酸降解性能，若干项研究采用间歇污水排放，取得了令人振奋的成果（赛义德1984年; Nadais等al.2006 ）。卡瓦莱鲁等人在2008年报告说使用脉冲控制来提高产甲烷菌对长链脂肪酸的降解，并建议连续操作的预期效果可能是下一阶段的由脉冲喂养得到的生物驯化。几项研究表明，使用絮状污泥而不是颗粒状污泥，在去除长
5、链脂肪酸（Nadais等al.2003）和处理复杂的废水（赛义德1987年）上会取得更好的效果。相比之下，絮状污泥似乎受长链脂肪酸抑制较少（胡等al.1996）。由于污泥反应器很难处理复杂的废水，所以常会使用预处理，如利用气浮进行脂肪分离。为了省去前期的油质分离获得一个紧凑的系统，两个上流式厌氧污泥床反应器进行了修改，引入一个新的理念：上流式厌氧污泥床通过沉降使得内部进行油脂分离，外部进行污泥再生。悬浮材料的使用完成了该系统，其目的是避免污泥处置。乌拉圭（合作社Lecheria日达拉梅洛）在本文提出，对这种替代污水处理系统的分析在达拉梅洛市的奶业中形成了真正的规模。乳制品工业废水脂肪含量已经高
6、于40 的总化学需氧量，平均流量约100 m3/d。材料和方法系统设计和运行 鉴于重大的负载和流量波动工厂的污水流，缓冲罐（平均水力停留时间为12小时）安装了上流式厌氧反应器。表1描述了缓冲池的出水特性，图1显示了完整的处理系统布局，其中包括缓冲池，两个40立方米的厌氧反应器（ R1和R2 ） ，一个固定板和一个片浮动材料的五立方米沼气池。 两个厌氧反应器排水到一个带着倾斜60 的金属片、间隔5厘米的固定板上，并且利用污泥泵是部分污泥回流，返回到供给槽。固定板要满负荷地运行15分钟时间。沉淀池的出口直接排放到市政污水管道。 一个用来提取浮动脂肪的漏斗状水槽被安装在两个反应器的废气罐内并且要低于
7、液位2cm。在每一个反应堆里，脂肪由水泵从一个作为脂肪手机接收水槽的外部空间提取的，其中漂浮材料被保留下来，顺着流出的水流被返回给反应器。 反应器从一个专门处理活性0.12gCH4-COD/gVSS.d甲烷的厌氧处理塘接种絮状污泥。间歇和替代的提供速率被用来启动和逐步提速的过程中。连续供给速度被用在120天的运行之后，并且达到污水厂所产生的160天之后的总共速率。造粒工艺依据Jeison和Chamy （ 1998 ）技术进行了分析，然后使用UTHSCA图像工具软件固定化颗粒琼脂。 浮动污泥沼气池在290天投入使用，以便从反应器稳定地提取浮泥。固体沼气池是接种污泥来自同一泻湖所使用的反应堆，并采
8、用条件下充分混合污泥回流泵的工作方式。该沼气池支持每天再循环8次。该沼气池出口流排入R1和R2以保持该系统的生物量稳定。 产生的沼气除了用来保持沼气池内容在温度32 和38 以外，还被用来增加3-4 的流反应器进水温度 。一个不锈钢材料的同心管用于增加进水和沼气池的温度。 通过以监测有机物去除的COD和脂肪和油的基础的数据记录和系统运行分析，对反应器的性能进行了评价。鉴于废水波动， 每周用冷冻24小时采集的样本对R1和R2进水和污水流进行分析。COD为联合确定的所有样品。参照该阶段之前使用的分析，以便确定可溶性化学需氧量COD和胶体化学需氧量，避免造成扭曲测量变量污泥结转。油脂分析每月使用相结
9、合的样品进水和污水流（标准方法， APHA ， AWWA ，世界经济论坛1995年）。每日针对进水和污水流样本点进行温度和pH测量记录;并且每周三次采用总碱度，重碳酸盐碱度和挥发性脂肪酸的滴定法测定基础样品点。每天监测数米外连接到的反应堆产生的沼气。 固定板执行每日测量settleable固体30分钟后的进水和出水流样本。利用监测率和挥发性固体清除率的脂肪和除油，对沼气池的性能进行了评价。交易量测量浮动了污泥提取的反应堆和美联储的沼气池;和沼气池进，出口样品分析了每周的总固体，挥发性固体和油脂。沼气池温度测量一天两次，开始和结束时的采暖期。 长链脂肪酸含量反映了长链脂肪酸的抑制效果，一批试验进
10、行了不同关系的长链脂肪酸/的VSS 。长链脂肪酸抑制测定分批运行使用钠棕榈酸酯，最丰富的牛奶甘油三酯和引物较小的长链脂肪酸存在于牛奶。上流式厌氧污泥床反应器是用来进行颗粒污泥测试的。三份测量是在150mL瓶不同浓度的生物量（表示的VSS ）和棕榈酸，而醋酸浓度显示表保持不变。结果与讨论污泥床反应堆 图2显示反应器的COD去除率（每周平均） 。去除效率保持在90 左右的COD负荷值增加的最多，为5.5kg/m3.d ;水力停留时间在最大负荷时保持有效时间约17小时。在整个实验过程中，反应器的温度波动范围为20 至30 ，并且对COD去除率没有产生太大影响。 运行的反应堆R1和R2分别开始使用44
11、0和400kgVSS（平均浓度值的11和10 kgVSS/m3 ）。图3显示的VSS演变。初期减少的5克/LVSS浓度是由于结转。两个反应堆之间又增加了约290 kgVSS污泥，250天恢复了初始浓度的污泥。R2的和R1分别在于肉芽开始在350天还是400天;R2的和R1分别还在于被测量的400天的小颗粒的平均粒径为0.57毫米还是0.45毫米。 造粒导致减少污泥结转，也会导致增加VSS浓度，上述的20克/ L的污泥容积指数从在inoculums的37mL /克以12mL /克下降完成。尽管在絮状污泥据报告中，有更有效治疗废水高长链脂肪酸浓度（佩雷拉等人。 2002年; Nadais ，等al
12、.2003 ），以及复杂的废水（赛义德1987年），然而颗粒污泥已自发在较高的有机负荷的阶段，从而提高了污泥停留能力。 结果是，微生物生长，反应器运转过程中经过消解和遗留的污泥可以顺利流出，从而避免了污泥的突然暴增。Integrated anaerobic treatment of dairy industrial wastewater and sludgeABSTRACTPerformance parameter were studied in an alternative full-scale dairy effluence treatment system comprising two
13、anaerobic sludge-blanket reactors in parallel arrangement with upward flow，internal fat-separation by flotation，external lamella settler and floated material digester. Reactors were initially inoculated sludge and granulated in a high-load stage. Using loading rates up to a maximum 5.5kgCOD/m3.d-hyd
14、raulic residence time of 17hours-reactor efficiency was found to remain stable around 90% of COD. Average sludge digester efficiency using a loading rate of 3.5kgVS/m3d with a lipid content of 47% of COD amounted to 78% of VS（87% of lipid removal）LCFA inhibition as assayed using palmitate was found
15、to depend not only on the palmitate concentration but also on the palmitate-to-biomass concentration ratio.INTRODUCTIONDepending on the type of product, equipment and unit processes entailed in processing of dairy-based products, effluent characteristics may vary widely according to industrial plant
16、. Thus, every individual situation must be considered separately with a view to ensuring appropriate treatment design (Demirel et al.2005).Nonetheless, on account of process leakage of milk or milk-based products, a number of constituents are systematically found in dairy industrial wastewater: lact
17、ose, lipids, casein and other proteins. Lipids, composed of triglycerides, are found mainly in emulsions resulting from initial process stage of homogenization. In addition, effluents will be acidic or basic according to chemical cleaning as used at anytime of process. The use of UASB reactors in da
18、iry wastewater treatment-as well as in the treatment of other complex effluents-has found limited success in view of the fact that a considerable amount of organic material hydrolyzes or degrades at an excessively low rate, while normally building up within the sludge blanket by entrainment or adsor
19、ption. The result is the dilution of biomass, the affectation of mass transfer properties and the impairment of sludge settling capacity. Sludge activity is therefore reduced and sludge washed out from the reactor in the outlet stream could occur(Sayed 1984;Sayed 1987;Rinzema 1993;Hwu et al.1998). R
20、apid adsorption and significantly slow degradation of dairy fat emulsions were reported for batch studies using biomass that was not adapted to degrading fats and a substrate load as high as 12.6 grams of fat per gram of VSS(Petruy & Lettinga 1997).Vidal et al.(2000) reported that fat-rich dairy was
21、tewater biodegradability rate is limited by fats hydrolysis. They performed batch assays with non-adapted biomass. However, using moderate loads and substrate-adapted microorganisms, hydrolysis may not be the rate limiting stage of total treatment process. Not limited by hydrolysis, total process ra
22、te may be limited by a reduced mass transfer rate due to LCFA adsorption onto sludge (Pereira et al.2003;Pereira et al.2004), or by the inhibitory effect of LCFA on acetotrophic methanogenic populations (Pereira et al.2005;Hwu et al.1996).According to research reported by Hwu et al.(1998), sludge fl
23、otation in UASB reactors due to LCFA adsorption may occur at lower LCFA concentration than those that produce inhibitory effect. With a view to studying the influence of the stage of adsorption preceding lipid and LCFA- degradation on the performance of UASB reactors, several studies were made using
24、 an intermittent effluent feed, leading to encouraging results (Sayed 1984; Nadais et al.2006).Cavaleiro et al.(2008) reported that use of pulse-feeds results in increased tolerance of acetotrophic methanogens to LCFA, and suggest that satisfactory results for continuous operation may be obtained fo
25、llowing a stage of biomass acclimatization by means of pulse-feed. Several studies demonstrated that the use of flocculent sludge rather than granular- results in a higher efficiency in removing LCFA(Nadais et al.2003) and treating complex effluents (Sayed 1987).In contrast, flocculent sludge appear
26、s to be less resistant to LCFA inhibition (Hwu et al.1996). As a result of difficulties in treating complex effluents in sludge-blanket reactors, pre-treatment methods are normally used, such as fat separation by means of flotation by dissolved air. In order to obtain a compact system without the ne
27、ed of previous fats separation, two UASB reactors were modified to introduce a novel concept: Upflow Anaerobic Sludge Blanket with internal fat separator and external sludge recovery by settling. The system is completed by a floated material digester with the objective of avoid sludge disposal. An a
28、nalysis of this alternative wastewater treatment system constructed at real scale in a dairy industry in Melo City, Uruguay (Cooperativa de Lecheria de Melo) is presented in this paper. This dairy industrial wastewater has lipid content higher than 40% of total COD, and the mean flow is about 100 m3
29、/d.MATERIALS AND METHODS System design and operationIn view of significant load and flow-rate fluctuations in the plants effluent stream，a buffer tank （average hydraulic residence time of 12 hours） was installed upstream of the anaerobic reactors. Table 1 depicts the effluent characteristics outlet
30、the buffer tank, and Figure 1 shows the complete treatment system lay-out, comprising the buffer tank, two 40m3 anaerobic reactors (R1 and R2), a lamella settler and a 5 m3 digester of floated material.Outlet effluents of both anaerobic reactors discharge to a lamella settler with plates tilted 60 a
31、nd spaced at 5cm, retaining part of the sludge carry-over from the reactors, returning it to the feed box by means of pumping equipment. The lamella settler operates at a residence time of 15 minutes at full-load. The settling tank outlet is discharged to municipal sewer.A funnel-shaped sink for ext
32、raction of floating fat was installed in both reactors, inside of the off-gas header and two centimeters, below liquid level. At each reactor, fat extraction was performed by pumping from an external chamber-acting as fat trap-receiving the discharge of the sink, whereby float material is retained,
33、returning the outlet stream of this chamber to the reactor.The reactors were inoculated with flocculent sludge from an anaerobic treatment lagoon of an abattoir with Specific Methanogenic Activity of 0.12gCH4-COD/gVSS.d. Intermittent and alternate feed rates were used at start-up, with rate increasi
34、ng gradually. Continuous feed rate was used after 120 day operation, reaching the total rate of wastewater generated by the plant 160 days after start-up. Granulation process was analysed following the Jeison and Chamy (1998) technique, immobilizing granules in agar and then using UTHSCA Image Tool
35、software.The float sludge digester was put in operation on day 290 in order to stabilize floating sludge extracted from the reactors. Solid digester was inoculated with sludge from the same lagoon as used for the reactors, and operated under full mixing conditions with sludge recirculation by means
36、of pumping. The digester hold-up was recirculated 8 times per day. The digester outlet stream was discharged into R1 and R2 in order to retain the systems biomass hold-up.Generated biogas was used to increase reactor influent stream temperature by 3-4, in addition to keeping the digester contents at
37、 a temperature between 32 and 38. A concentric tubes exchanger constructed in stainless steel was used to increase the temperature of the influent and of the digester content.Data recording and system operation analysisReactor performance was evaluated by monitoring the organic matter removal on a C
38、OD and a fat-and-oil basis. In view of wastewater fluctuations, R1 and R2 influent and effluent streams were analyzed weekly using refrigerated 24-hour samples collected daily. COD was determined for all combined samples. A setting stage was used prior to analysis, so that COD determinations include
39、 soluble COD and colloidal COD, avoiding distorted measurement resulting from variable sludge carry-over. Fats and oils were analyzed monthly using combined samples of influent and effluent streams (Standard Methods, APHA, AWWA, WEF 1995). Temperature and PH measurements were recorded daily for poin
40、t samples of the influent and effluent streams; and total alkalinity, bicarbonate alkalinity and volatile fatty acids were determined by titration for point samples on a three-per-week basis. Generated biogas was monitored daily by meters connected to either reactor.Lamella settler performance was e
41、valuated by daily measurement of settleable solids in after 30 minutes, for both influent and effluent stream samples.Digester performance was evaluated by monitoring the rate of volatile solid removal and the rate of fat-and-oil removal. Daily volume measurement were made of floated sludge extracte
42、d from the reactors and fed to the digester; and digester inlet and outlet samples were analysed on a weekly basis for Total Solids, Volatile Solids and Fats and Oils. Digester temperature was measured twice a day, at the beginning and end of the heating period.Assaying LCFA inhibitionTo evaluate th
43、e effect of LCFA inhibition, batch tests were carried out with different relationships of LCFA/VSS. LCFA inhibition was assayed in batch runs using sodium palmitate-the largest abundant of milk triglycerides and primer of smaller LCFA present in the milk. Granular adapted sludge from the UASB reacto
44、rs was used to perform the tests. Triplicate measurements were made in 150mL vials with varying concentration of biomass (expressed as VSS) and palmitate, while the acetate concentration was kept constant as shown in Table2.RESULTS AND DISCUSSIONSludge blanket reactorsFigure 2 shows reactor feed loa
45、ds and removal efficiency in COD (weekly average). Removal efficiency remained at a value around 90% of COD for load values increasing up to 5.5kg/m3.d; the hydraulic residence time remaining at a value around 17hours during the maximum load stage. Reactor temperature fluctuated within the range of
46、20 to 30 throughout the experiment and did not appear to have a significant effect on the COD removal efficiency.Operation of the reactors R1 and R2 was started with 440 and 400kgVSS, respectively (mean concentration values of 11 and 10 kgVSS/m3). Figure 3 shows the VSS evolution. A reduction in VSS
47、 concentration to 5g/L during the initial stage was due to carry-over. About 290 kgVSS of sludge were added to both reactors between days 162 and 250 to recover the initial concentration of sludge. Granulation started around days 350 and 400 for R2 and R1 respectively; on day 400 small granules of a
48、n average size of 0.57mm and 0.45mm were measured in R2 and R1 respectively. Granulation resulted in a reduction in sludge carry-over and led to an increase in VSS concentration to above 20g/L. The sludge volume index decrease from 37mL/g in the inoculums to 12mL/g upon completion of granulation. In
49、 despite flocculent sludge has been reported to be more efficient in the treatment of effluents with a high LCFA concentration (Pereira et al. 2002;Nadais,et al.2003) as well as complex effluents (Sayed 1987), the sludge has granulated spontaneously in the higher-organic load stage, resulting in improved sludge retention capacity.The resulting combined effect of microbial growth, sludge supply from