How to Survive — and Excel in — Your College Years
by Randall S. Hansen, Ph.D.
Perhaps you were class president in high school. Or perhaps you were a member of the honor society. You could have graduated in the top percentile of your graduating class; perhaps you were even valedictorian. Maybe your were in the honors program or the International Baccalaureate program. Actually, it doesn’t really matter what you did in high school as you make the transition to college. High school success (or lack of it) doesn’t automatically apply to college.
You start college with a clean academic slate, along with a lot of independence and a myriad of critical decisions as you begin the transition into adulthood. The decisions that you make and the actions you take during this first year of college will have a major impact on the rest of your college experience.
According to American College Testing (ACT), one in every four college students leaves before completing their sophomore year —and nearly half of all freshmen will either drop out before obtaining a degree or complete their college education elsewhere.
But wait! This article is not meant to scare you or take away any of the joy, excitement, and anticipation you feel about going to college. Quite the opposite. This article is all about the things you need to do to not only survive your first year of college, but to thrive in college. And many of the tools, skills, and habits you develop through this article can not only be used to help you succeed in college, but in your future career as well.
The first few weeks on campus are extremely critical for all new students. It is during this time that you make critical decisions that will have an effect on the rest of your life. Some of these 25 tips are critical during your first weeks, while the others are meant for longer-term guidance and survival. Whatever you do, be sure to be yourself and try to enjoy your college experience as much as
possible. Expect to feel some stress and homesickness, but don’t let these issues wear you down.
25 Strategies and Tips to Help You Survive and Thrive Your Freshman Year
1 Go to all orientations. Do you really need to go on yet
another campus tour? Yes. The faster you learn your way
around campus — and around all the red tape — the more at ease you’ll feel and the better prepared you’ll be when issues arise.
2 Get to know your roommate and others in your residence
hall. The people you live with, most of whom are going
through similar experiences and emotions, are your main
safety net — not only this year, but for all your years. You may change roommates after the first semester or you may stay
roommates for all four years — just take the time to get to
know your fellow first-year students.
3 Get Organized. In high school, the teachers tended to lead
you through all the homework and due dates. In college, the
professors post the assignments — often for the entire
semester — and expect you to be prepared. Buy an organizer, use an app, or get a big wall calendar — whatever it takes for you to know when assignments are due.
4 Find the ideal place for you to study. It may be your dorm
room or a cozy corner of the library, but find a place that works best for you to get your work done — while avoiding as many distractions as possible.
5 Go to class. Obvious, right? Maybe, but sleeping in and
skipping that 8 am class will be tempting at times. Avoid the
temptation. Besides learning the material by attending classes, you’ll also receive vital information from the professors about
what to expect on tests, changes in due dates, etc.
6 Become an expert on course requirements and due dates.
Professors spend hours and hours preparing course syllabi
and calendars so that you will know exactly what is expected
of you — and when. One of the lamest excuses a student can give a professor: ―I didn’t know it was due today.‖
7 Meet with your professors. Speaking as a professor, I can
assure you there are only upsides to getting to know your
professors, especially if later in the semester you run into
some snags. Professors schedule office hours for the sole
purpose of meeting with students — take advantage of that
time.
8 Get to know your academic adviser. This is the person who
will help you with course conflicts, adding or dropping courses, scheduling of classes for future semesters, deciding on majors and minors. This person is a key resource for you — and
should be the person you turn to with any academic issues or conflicts. And don’t be afraid of requesting another adviser if you don’t click with the one first assigned to you.
9 Seek a balance. College life is a mixture of social and
academic happenings. Don’t tip the balance too far in either
direction. One of my favorite former students always used to say her motto was to ―study hard so she could play hard.‖
10 Get involved on campus. A big problem for a lot of new
students is a combination of homesickness and a feeling of not quite belonging. A solution? Consider joining a select group —and be careful not to go overboard — of student organizations, clubs, sororities or fraternities, or sports teams. You’ll make
new friends, learn new skills, and feel more connected to your school.
11 Strive for good grades. Another obvious one here, right?
Remember the words of the opening paragraph; while good
grades could have come naturally to you in high school, you will have to earn them in college — and that means setting
some goals for yourself and then making sure you work as
hard as you can to achieve them.
12 Take advantage of the study resources on campus. Just
about all colleges have learning labs and tutors available. If
you’re having some troubles, these resources are another tool available to you. Another idea: form study groups.
13 Make time for you. Be sure you set aside some time and
activities that help you relax and take the stress out of your
day or week. Whether it’s enlisting yoga techniques, watching your favorite television shows, or writing in a journal, be good to yourself.
14 Don’t feel pressured to make a hasty decision about a
career or a major. It doesn’t matter if it seems as though
everyone else seems to know what they’re doing with their
lives — believe me, they don’t— college is the time for you to really discover who you are, what you enjoy doing, what you’re good at, and what you want to be. It’s not a race; take your
time and enjoy exploring your options.
15 Take responsibility for yourself and your actions.Don’t
look to place the blame on others for your mistakes; own up to them and move on. Being an adult means taking responsibility for everything that happens to you.
16 Make connections with students in your classes. One of
my best students said his technique in the first week of classes was to meet at least one new person in each of his classes. It expanded his network of friends — and was a crucial resource at times when he had to miss a class.
17 Find the Career Services Office. Regardless of whether you
are entering college as undeclared or have your entire future mapped out, seek out the wonderful professionals in your
college’s career services office and get started on planning,
preparing, and acting on your future.
18 Don’t procrastinate; prioritize your life. It may have been
easy in high school to wait until the last minute to complete an assignment and still get a good grade, but that kind of stuff will not work for you in college. Give yourself deadlines — and
stick to them.
19 Stay healthy/Eat Right. A lot of problems first-year students
face can be traced back to an illness that kept them away from classes for an extended period of time that led to a downward spiraling effect. Get enough sleep, take your vitamins, and eat right. If you haven’t heard the jokes about college food, you
soon will. And without mom or dad there to serve you a
balanced meal, you may be tempted to go for those extra fries or cookies. Stay healthy and avoid the dreaded extra
―Freshman 15‖ pounds by sticking to a balanced diet.
20 Learn to cope with homesickness. It’s only natural that there
will be times when you miss your family, even if you were one of those kids who couldn’t wait to get away. Find a way to deal
with those feelings, such as making a phone call or sending
some email home.
21 Stay on campus as much as possible. Whether it’s
homesickness, a job, or a boyfriend or girlfriend from home, try not to leave campus too soon or too often. The more time you spend on getting to know the campus and your new friends,
the more you’ll feel at home at school. And why not take
advantage of all the cultural and social events that happen on campus?
22 Seek professional help when you need it. Most colleges
have health and counseling centers. If you’re sick or feeling
isolated or depressed, please take advantage of the many
services these offices provide students. You don’t have to face these issues by yourself.
23 Keep track of your money. If you’ve never had to create a
budget, now is the time to do so. Find ways to stretch your
money – and as best you can, avoid all those credit card
solicitations you’ll soon be receiving. The average credit card
debt of college grads is staggering.
24 Don’t cut corners. College is all about learning. If you
procrastinate and cram, you may still do well on tests, but
you’ll learn very little. Even worse, don’t cheat on term papers or tests.
25 Be prepared to feel overwhelmed. There’s a lot going in your
life right now. Expect to have moments where it seems a bit
too much. As one student says, be prepared to feel completely unprepared. The trick is knowing that you’re not the only one
feeling that way.
Final Words of Advice for First-Year College Students You’ve done all the prep work — you’ve gotten good grades in high school, scored well on a standardized test, and been accepted into the college you want to attend — so enjoy all your hard work while laying the groundwork for a successful college career. Don’t be a statistic; be determined to make it through your freshman year —and beyond. Take advantage of your network of new friends and professors, have fun while learning as much as you can, and get the most out of your college experience.
中空纤维超滤膜装置 使用说明书 济宁市鲁源水处理有限公司
一、超滤工作原理 超滤膜工作原理 超滤是一种膜分离技术,是以膜两侧压力差为驱动力,机械筛分原理为基础的一种溶液分离过程。超滤的过滤孔径在0.002?0.1μm,截留分子量在30000?100000 道尔顿。过滤时小分子溶质和溶剂可以透过膜的微孔,而大分子溶质不能透过,被截留在膜的一边,从而实现物质的分离。 二、超滤的特点及主要技术指标 1、超滤的特点 ⑴膜的化学材料 UFIA(B)系列超滤膜组件的膜材质为亲水性聚醚砜,这种材质化学稳定性优异,强度高,亲水性好,耐污染性强,耐酸碱性范围PH2?13。 ⑵膜微孔结构和孔径UFIA(B)系列超滤膜的中空断面为海绵状多孔结构,内表面为致密的分离层,外表面为支撑层。这种结构使得超滤
产水水质更优。膜的截留分子量为50000 道尔顿。 中空纤维超滤膜电镜照片 ⑶超滤膜组件结构 中空纤维超滤膜组件有内压式和外压式两种操作方式,外压式的进水流道是膜丝之间,内压式的进水流道是中空纤维内腔,UFIA(B)系列膜组件为内压式超滤膜。 2、膜天超滤的主要技术指标 ⑴、材质:聚醚砜 ⑵、工作压力:≤0.25MPa ⑶、工作温度:≤45℃ ⑷、pH 范围:2~13 ⑸、操作模式:内压式 ⑹、最大进水压力:≤0.3 MPa ⑺、最大跨膜压差:≤0.15 MPa ⑻、最大反洗压力:≤0.2 MPa
⑼、反洗水通量:100~150L/m2h ⑽、化学清洗试剂:柠檬酸,氢氧化钠,次氯酸钠 3、超滤进水水质要求 为防止不良水质进入超滤膜组件而对膜组件产生严重污堵,对进入超滤膜组件的水应满足以下要求: ⑴、浊度:≤10NTU ⑵、颗粒物直径:<0.5mm ⑶、铁离子:<0.5mg/L ⑷、CODcr:<20mg/L ⑸、pH 范围:2?13 ⑹、有机溶剂:不得含有醇、酮、苯等有机溶剂 ⑺、瞬时余氯耐受量:300ppm 注: ①当水中含油、有机物、氧化性物质(余氯、O3、H2O2 等)、表面活性剂、消泡剂时,请与我公司技术支持部联系,在技术工程师指导下使用。 ②当系统预处理中采用絮凝工艺,要进行杯试并严格控制絮凝剂量,絮凝剂量过多或过少都将对膜产生污染影响膜的透水通量。 ③进水有藻类、微生物时,要加入15?50mg/l 杀菌剂,防止藻类或微生物滋生和污染膜。 三、一般超滤系统的设计 1 超滤系统配置
中空纤维超滤装置操作维护手册 1、超滤工作原理 中空纤维超滤膜分离技术是一种广泛应用于溶液和气体物质分离、浓缩和提纯的分离技术。它利用具有选择透过能力的薄膜做分离介质,膜壁密布微孔,原液在一定压力下通过膜的一侧,溶剂及小分子溶质透过膜壁为滤出液,而较大分子的溶质被膜截留,从而达到物质分离及浓缩的目的。膜分离过程为动态过滤过程,大分子溶质被膜壁阻隔,随浓缩液流出膜组件,膜不易被堵塞,可连续长期使用。过滤过程可在常温、低压下运行,无相态变化,高效节能。 中空纤维膜是分离膜的一种重要形式。在单位体积膜组件中,中空纤维膜的有效膜面积最大,过滤分离效率高,容易清洗,结构简单,操作方便,在生产过程中不产生二次污染。该结构是中空纤维膜结构,由纤维挤压形成。这种纤维具有非对称结构且细如发丝。数百万支纤维形成一束,将等长的多孔塑料管插入束中作给水分布器。纤维束两端用环氧树脂封装,一头密闭,一头开口形成产水流道。 中空纤维膜采用进口聚砜材质膜元件,外压式结构,化学稳定性优越,耐氧化剂能力强,亲水性好,污堵后容易清洗恢复。原水经前级过滤后进入中空纤维膜元件,产水由中空纤维膜中心出水孔流出,浓水流出,同时带走膜表面的污染物。 超滤组件选用湖州东洋水处理设备有限公司生产的CZW-1614A中空纤维膜元件,该膜元件属外压型超滤膜,具有结构紧凑,产水量特别大,操作压力低,耐余氯侵蚀性好,适用PH范围广的优点。 超滤膜元件为PS材质,在水质处理过程中无相变,体积小,易于实行编程自控,适应范围广,无环境污染等优点。超滤膜组件规格为:φ160×1380,截留分子量50000,单根实际产水流量≥5000l/h、25℃,设计产水流量≥1200l/h、25℃。回收率为80-90%。 中空超滤装置性能指标 表1
中空纤维超滤膜设备使用说明 1、设备进入厂房内,平稳安装后,在原水泵进水口上接入水源,在纯水出口处、废水排放处连接出水管道,然后把配电箱的主线接入电源,为安全起见,在增压泵底角螺丝处接入地线。 2、电源接通后检查原水泵、增压泵是否能够正常工作。 3、打开原水泵反复冲洗多介质过滤器,直到多介质过滤器内的水流变清,然后冲洗活性炭过滤器,直到活性炭过滤器内的水流变清,然后关闭活性炭过滤器的控制阀门,预处理部分冲洗完毕。 4、启动原水泵让水流通过预处理系统进入精密过滤器,打开精密过滤器上的排气阀,把空气排出后关闭排气阀,启动增压泵让水流进入超滤系统,调节阀完全打开,反复冲洗超滤膜,30分钟后超滤系统冲洗完毕。 设备工作操作说明 1、打开水源,启动原水泵、增压泵,然后调节控制阀把纯水流量调节到额定状态,纯水流量与废水流量请参照流量计。 2、设备工作时若原水供应不足,设备电路进入自动保护状况,设备停止工作。停水状态下不得强行启动增压泵。 3、操作结束后,首先关闭增压泵,再关闭原水泵,然后关闭水源,最后切断电源。 设备保养说明 1、经常检查原水泵、增压泵、断水保护器、供电系统是否完好。 2、精密过滤器内的溶喷滤芯需要经常洗涤,定期更换。 3、原水水质的优劣程度,纯水产量的大小直接影响超滤膜的使用寿命,为保证超滤膜正常工作,需要对超滤膜进行定期维护,此项工作必须由专业人员或在专业人员的授意下完成,非专业人员或未征得专业人员授意不得擅自清洗、拆卸、对超滤膜进行随意处理。如若
非经本厂专业人员授意,随意拆卸原水泵、增压泵、断水保护、超滤系统等主机主要部件,造成损坏的,本厂概不负责。 4、设备闲置时,必须断水断电,放净设备内所有积水,设备不得在高温与零下温度的环境内放置。 超滤膜产品的性能 中空纤维超滤膜是一种半透膜,采用化纤性良好的聚砜材料,运用相转换法制成,分离精度介于微滤和纳滤之间,是通过筛分原理分离,截留分子量1000-100000Dalton可选,适应于大分子物质与小分子物质分离、浓缩和纯化过程。 超滤膜的产品特点 采用“干态”保存,保存期长达18个月; 采用高压成膜,硬度高、易清洗,进水方式为内压式; 具有精度高、出水量稳定、不易堵塞等特点。 超滤膜广泛应用于 反渗透装置的前处理; 饮料、自来水、矿泉水行业净化除菌浓缩; 乳品、生物制药行业的分离与提纯; 生活污水及工业废水的处理; 油田回注水的净化; 冷却水的回用处理以及需要水进一步净化的其他工业应用。 超滤膜的使用说明 1、器件在使用前,须冲净保护剂,必要时应结合系统重新进行杀菌; 2、冲净保护剂或杀菌液后,用纯水或超滤水清洗、直至清洗干净、然后投入使用; 3、杀菌:用杀菌液注入器件内,先循环后浸泡1小时左右,然
中空纤维超滤膜应用指南 一、超滤的基本概述 超滤是一种将溶液进行净化、分离或浓缩的膜透过法分离技术。20多年来发展迅速,已成为膜分离领域中最为广泛应用的品种之一。其应用面非常广泛,小至家用净水器,大到现代工业生产,从普通民用到高新技术领域都有不同规模的应用,甚至于在环境保护方面也有极大的使用潜力,超滤是一种最有发展前途的膜法分离技术。 二、超滤膜组件的基本类型 目前,工业上常用的超滤膜器件主要有下列五种类型:板框式、园管式、螺旋卷式、中空纤维式、毛细管式,其主要特征列于下表。 各种基本类型膜均有不同的适用性,在工业上应用最为广泛的是中空纤维式,特别是在净化、分离的应用中。而在粘度较高的溶液净化、分离、浓缩过程中,则板框式或园管式有更大的适用性。
三、超滤膜的超滤特性 在膜分离技术范畴内,分离精度自反渗透至微滤过滤范围的连续谱图中可见,超滤介于纳滤与微滤之间。 膜过滤谱图 超滤的定义域为截留分子量500~500000左右,相应膜孔径大小的近似值为0.002μ~0.1μ。截留分子量与膜孔径两者尚无对应关系。简单的理解,超滤膜如同筛子,在一定压力(0.1~0.6MPa)下,允许溶剂和小于膜孔径的溶质透过,而阻止大于孔径的溶质通过,以完成溶液
的净化、分离和浓缩。 超滤过程有如下特点: (1)超滤过程无相际变化,可以在常温及低压下进行分离,因而能耗低,约为蒸发法与冷冻法的1/2~1/5; (2)设备体积小,结构简单,故投资费用低,易于实施; (3)超滤分离过程只是简单的加压输送液体,工艺流程简单,易于操作管理; (4)溶液在分离、浓缩过程中不发生质的变化,因而适合于保味及热敏性溶液的处理; (5)适合于从稀溶液中分离微量贵重大分子物质的回收和低浓度大分子物质的回收; (6)能将不同分子量的物质分级分离; (7)超滤膜是由高分子聚合物制成均匀的连续体,在使用过程中无任何杂质的脱落,保证被处理溶液的纯净。 由以上分离特性可知,超滤的应用范围很广,但归根到底,主要应用于溶液的净化、分离和浓缩。 四、超滤技术的特性参数 超滤技术特性参数主要指分离透过性能: (1)透水速率(超滤速率): 在一定工作压力、温度下,单位面积(在研究领域中)或单个组件
中空纤维超滤膜在使用中应注意事项: A、过滤系统要定期灭菌。超滤膜可以截留细菌,但不可以杀死细菌,截留率再好的超滤膜也不能长期保证干净区不长一个细菌,有细菌就可能大量繁殖。直接影响到透过水质,譬如有的矿泉水成品中出现半透明丝状白色絮状的霉菌团,主要是系统被霉菌污染所致。因此,必须定期对周转环境及过滤系统进行定期灭菌,灭菌的操作周期因供给原水的水质情况而定,对于城市普通自来水而言,夏季7~10天,冬季30~40天,春秋季20~30天。地表水作为供给水源时,灭菌周期更短。灭菌药品可用500~1000mg/L次氯酸钠溶液或1%过氧化氢水溶液循环流或浸泡约半小时即可。 B、由于每根超滤组件在出厂前加入保护液,使用前要彻底冲洗组件中的保护液。先用低压(0.1MPa)给水冲洗1小时,然后再用高压(0.2MPa)给水冲洗1小时,无论低压还是高压冲洗时,系统的产水排放阀均应全部打开。在使用产水时,应检查并确认产品水中不含有任何杀菌剂。 C、超滤组件要轻拿轻放,并注意保护。由于超滤组件是精密器材,所以在使用安装时要小心,要轻拿轻放,更不能甩坏。组件若停用,要先用清水冲洗干净后,加0.5%甲醛水溶液进行消毒灭菌,并密封好。如冬天组件还要进行防冻处理,否则组件可能报废。 中空纤维帘式膜组件Products(膜天膜) 工作原理: 中空纤维帘式膜过滤是一个压力驱动的膜分离过程,它能够将颗粒物质从流体及溶解组份中分离出来。对于胶体、淤泥、藻类、隐孢子虫、贾地鞭毛虫、大肠杆菌、细菌和大多数病毒等具有很高的去除率,产水方式为负压吸抽或重力静压出水。 膜组件规格与参数: 规格 FP-A1 FP-A215 FP-A4 过滤方式负压或者重力静压 材质聚偏氟乙烯 膜特性亲水非对称膜 粘接材料环氧树脂 接口材料工程塑料ABS 膜面积12.5m220m225m2孔径0.10μm 使用完整性检测压0.1MPa
1. 说明 在使用膜组件之前,请您认真阅读本技术手册。 2.膜组件简介 近几年来,由于水资源的短缺以及严重的水污染问题,膜独特的分离技术脱颖而出。膜设备分离占地空间小,操作方便,能耗小,分离效率高且出水水质好,因而在许多领域得到广泛应用。 中空纤维超滤膜及微滤膜是以优质的聚偏氟乙烯(PVDF)为原材料,采用先进的技术及精密的生产设备,在严格的工艺条件下生产制造而成。膜组件主要有柱式和帘式两种形式不同规格的产品。 PVDF膜组件更因其独特的抗氧化性,易清洗的特点,在污水处理、中水回用、自来水净化方面可广泛应用。我们生产的膜组件强度高,水通量大,产水水质好,抗污染性强,产水量稳定,适用的水质范围宽。产品使用寿命长,性价比高。 3. 膜生物反应器(MBR) 膜生物反应器(MBR)是把膜分离技术与生物技术相结合的新型污水处理高新技术。也就是把膜处理工艺与传统的活性污泥法相结合,用膜组件代替传统活性污泥法中的二沉池,利用膜的高效截留作用,进行固液分离,从而构成里膜生物反应器污水处理工艺。 这是一种新型高效的污水处理工艺。在污水处理领域已备受瞩目,被认为是21世纪世界上最有发展的高新技术之一。经MBR处理后的污水可以直接回用。出水水质良好且稳定,不仅能够完全去除悬浮物,并且可以去除几乎所有的细菌与病毒,产水浊度接近于零,对主要污染物的去除率很高,节流
减排,实现了污水资源化。因此,膜生物反应器在世界污水处理领域越来越得到广泛应用。 3.1 MBR的优势 1:高效的固液分离技术,使分离效果远好于普通的二次沉淀池,能够完全去除产水中的悬浮物,产水浊度接近于零,产水水质良好且稳定。产水可以直接回用。 2:由于MBR将传统污水处理的曝气池与二沉池合二为一,大幅减小占地面积,并节省土建资源。 3:生物处理单元的污泥浓度高,泥龄厂,从而大大提高了难降解的有机物的降解效率。同时,由于活性污泥的吸附作用,使主要污染物(COD)的去除率可达90%以上。 4:由于膜的截留作用,硝化细菌被完全截留在生物反应器内,并且繁殖,增强了系统的硝化能力,提高了氮、磷等污染物的去处。 5:反应器在低有机负荷率情况下运行,剩余活性污泥量远低于传统工艺法的活性污泥量,无污泥膨胀,降低了对剩余污泥的处置费用。 6:系统实现自动控制(PLC),操作管理方便,噪音小。 3.2 MBR的应用领域 1:大型市政污水处理,达到中水回用标准。 2:生活小区,写字楼,学校等中小型污水处理,中水回用工程。 3:厂矿企业污水处理,中水回用工程等。 4:市政自来水领域。 4.膜组件
中空纤维超滤膜装置 使用说明书
市鲁源水处理 一、超滤工作原理 超滤膜工作原理 超滤是一种膜分离技术,是以膜两侧压力差为驱动力,机械筛分原理为基础的一种溶液分离过程。超滤的过滤孔径在0.002?0.1μm,截留分子量在30000?100000 道尔顿。过滤时小分子溶质和溶剂可以透过膜的微孔,而大分子溶质不能透过,被截留在膜的一边,从而
实现物质的分离。 二、超滤的特点及主要技术指标 1、超滤的特点 ⑴膜的化学材料 UFIA(B)系列超滤膜组件的膜材质为亲水性聚醚砜,这种材质化学稳定性优异,强度高,亲水性好,耐污染性强,耐酸碱性围PH2?13。 ⑵膜微孔结构和孔径UFIA(B)系列超滤膜的中空断面为海绵状多孔结构,表面为致密的分离层,外表面为支撑层。这种结构使得超滤产水水质更优。膜的截留分子量为50000 道尔顿。 中空纤维超滤膜电镜照片 ⑶超滤膜组件结构 中空纤维超滤膜组件有压式和外压式两种操作方式,外压式的进水流道是膜丝之间,压式的进水流道是中空纤维腔,UFIA(B)系列膜组件为压式超滤膜。
2、膜天超滤的主要技术指标 ⑴、材质:聚醚砜 ⑵、工作压力:≤0.25MPa ⑶、工作温度:≤45℃ ⑷、pH 围:2~13 ⑸、操作模式:压式 ⑹、最大进水压力:≤0.3 MPa ⑺、最大跨膜压差:≤0.15 MPa ⑻、最大反洗压力:≤0.2 MPa ⑼、反洗水通量:100~150L/m2h ⑽、化学清洗试剂:柠檬酸,氢氧化钠,次氯酸钠 3、超滤进水水质要求 为防止不良水质进入超滤膜组件而对膜组件产生严重污堵,对进入超滤膜组件的水应满足以下要求: ⑴、浊度:≤10NTU ⑵、颗粒物直径:<0.5mm ⑶、铁离子:<0.5mg/L ⑷、CODcr:<20mg/L ⑸、pH 围:2?13 ⑹、有机溶剂:不得含有醇、酮、苯等有机溶剂 ⑺、瞬时余氯耐受量:300ppm 注:
XIGA TM 原理和操作手册 目录 工艺描述 XIGA TM原理 储存和运输 安装膜组件 开机程序 膜完整性测试 组件修复程序
工艺描述 由于高寿命的膜技术的发展,微滤和超滤已经应用到大规模的过滤过程中,而且这种进展由于采用了被许多超滤过程采用的错流过滤,而更加具有吸引力。错流的方式确实提高了超滤和微滤过程的表现。但是一个致命的缺陷妨碍了这种过滤方式在大规模的过滤过程中的应用:这就是非常高的运行能耗。 X-FLOW的XIGA TM-使得微滤和超滤工艺使用终端过滤(Dead-end mode)成为可能。采用这种过滤模式的运行能耗仅仅为错流过滤能耗的一小部分。并且在这种工艺中,X-FLOW 发明了一种采用 永久亲水毛细管膜的新组件。组件的设计采用8”形式,这是卷式膜,尤其是卷式反渗透膜采用的一种标准形式。标准压力容器中,可以放入多个膜组件,进水方式可以为一端进水,也可以为两端进水。两端进水的好处是可以减轻压力损失,因此保证在整个压力容器长度方向上,均可以获得稳定的出水量。 通常工艺采用,出水量恒定的方式。因此,膜过滤压降(TMP)将随着过滤过程的进行不断升高。这就需要间隔一段时间,就进行反洗,来控制TMP的升高。同时我们还推荐,间歇地加入双氧水、次氯酸等消毒剂来控制细菌的增长,有助于减少TMP的增加。另外,还需要每月左右进行化学清洗清洗剂可采用氢氧化钠、EDTA、柠檬酸等。 根据XIGA TM概念设计的大型膜过滤工厂PWN/荷兰
XIGA TM原理 过滤 XIGA TM组件由PVC外筒和中心出水管,以及中空纤维膜丝组成,膜丝材料为聚醚砜和聚乙烯吡咯酮共混材料。中空纤维膜丝由2-3cm的环氧树脂密封在PVC外筒中,原水从毛细管的内部进入。过滤时,比膜孔径大的颗粒被截留在膜的表面,并存留在毛细管间。而滤液,以及包含在滤液中的离子和小于膜孔径的颗粒物通过膜表面,并被收集到中心集水管中。 上述即为过滤过程。过滤过程的驱动力来自入水(进入毛细管)和出水(出毛细管)之间的压力差,即所谓的过滤压降(TMP)。由于XIGA TM采用了终端过滤,因此TMP非常低,通常为0.5bar。虽然随着操作的进行TMP会不断增加,但是保持低水平的TMP是非常重要的。过滤过程的TMP不能超过1bar超过1bar的过滤压降,会导致在膜的表面形成无法反洗掉的污垢。 根据入水水质和使用的膜的种类不同,典型的过滤膜通量为70-100L/m2.h,间歇过滤的时间为10-60分钟。 反洗 如果不及时除去,保留在毛细管膜表面的颗粒物将堵塞膜孔,从而使TMP增加。因此间歇性的反洗是必须的。在反洗时,反洗水的水流方向与过滤时相反。干净的过滤出水,在压力作用下,从毛细管膜的外部向内部冲洗,从而将污垢带出毛细管膜。同样,在反洗过程中控制TMP同样重要。反洗最大TMP为3bar。反洗过程中TMP,并非唯一重要指标。将污物运出毛细管的速度同样为重要指标,推荐反洗的膜通量为250-300L/m2.h。另外,反洗时间要保证能够将所有污物清洗除去;并且不仅仅是清除出膜组件,而且要保证清除出膜系统(包括压力容器)。通常所采用的反洗时间为30-40秒。