当前位置:首页 >> 电力/水利 >>

WASTE WATER REUSE 回用


Desalination 149 (2002) 137–143

Experimental campaigns on textile wastewater for reuse by means of different membrane processes
M. Marcucci*, G. Ciardelli, A. Matteucci, L. Ra

nieri, M. Russo
Tecnotessile S.r.l., via del Gelso 13, I-59100 Prato, Italy Tel. +39 (0574) 634040, Fax +39 (0574) 634045; email: chemtech@tecnotex.it

Received 7 February; accepted 4 April 2002

Abstract The experimental results of the pilot scale application of different membrane technologies, supported by clariflocculation and ozonization, for textile wastewater reuse are described. The investigation has been carried out by treating two different textile effluents: a secondary effluent coming from a biological activated plant and a wastewater coming directly from several textile departments. In the first case the pilot plant used sand filtration and microflitration (MF) as pre-treatments for nanofiltration (NF). The MF and NF membranes tested were of the spiral wound type. The NF permeate can be reused in all production steps, including dyeing with light coloration. In the second case, the chemical-physical pre-treatment and the advanced treatment of water have been experimented for different kind of wastewater (from the carbonising process, from dyeing and fulling). The most interesting experimental results were obtained from the treatment of wastewater from the carbonising process. A scheme process in which ultrafiltration (UF) with flat membranes operating under vacuum is placed downstream an ozonization treatment has been evaluated. The UF permeate quality was suitable to the reuse in production processes. Keywords: Wastewater treatment; Ultrafiltration; Nanofiltration; Ozonization; Colour removal

1. Introduction 1.1. Textile wastewater characteristics In Europe, increasing water consumption for industrial and domestic uses is leading to potential water shortage in many countries. European in*Corresponding author.

dustries are also faced with increasing costs for water supply and wastewater depuration and with more stringent controls on industrial effluent pollution, in accordance to the European Union legislation in force [1]. Textile factories are among the largest industrial consumers of water: typically 0.2–0.5 m3 of water are needed to produce 1 kg of finished product

Presented at the International Congress on Membranes and Membrane Processes (ICOM), Toulouse, France, July 7–12, 2002. 0011-9164/02/$– See front matter ? 2002 Elsevier Science B.V. All rights reserved

138

M. Marcucci et al. / Desalination 149 (2002) 137–143

[2]. Therefore, textile industry, which is widespread throughout Europe, is a good candidate for development of intensive water recycling and minimization of related polluting emissions. Textile effluents contain many chemical substances coming from desizing, dyeing, printing and finishing processes. Moreover textile wastewater quality is variable with time and may include many types of dyes, detergents, sulphide compounds, solvents, heavy metals and inorganic salts, their amounts depending on the kind of process that generates the effluent [3]. Textile wastewater is usually treated in an activated sludge plant to allow wastewater discharge within law requirements but not in order to produce a final effluent suitable for reuse in the textile processes. In fact, a considerable amount of recalcitrant contaminants still remain in biologically treated textile effluents. So, in order to have water that can be recycled in production cycles (especially dyeing processes), water needs further treatments (called tertiary or advanced treatments) [4]. The techniques which have been experimented and applied to the textile effluents treatment in order to produce water to be reused in production, are numerous, such as ozonation, Fenton’s reagent oxidation, electrolysis, flotation. The authors performed several experimental campaigns and, according to their knowledge, membrane technologies turned out to be the most interesting ones. 1.2. Membrane processes for treatment and reuse of textile effluents The interest in membrane processes applied to textile wastewater reuse is increasing thanks to the recent technological innovations that render them reliable and economically feasible in alternative to other systems. Several approaches have been proposed to implement membrane technology to the treatment of textile wastewater from different production streams. Reverse osmosis (RO) and nanofiltration (NF) were studied as treatment of secondary textile

effluents after a suitable pre-treatment, such as ultrafiltration or microfiltration [5]. Microfiltration (MF) allows a simple clarification of the effluent, removing suspended particles (microorganism, inorganic particles, colloids). Ultrafiltration (UF) is effective for removal of particles and molecules of dimensions higher than 10 nm, bacteria, viruses and proteins. MF and UF are generally proposed as RO pretreatment [6]. The choice of the most suitable membrane process on a technical-economic point of view for the textile wastewater treatment and reuse is often validated by carrying out experimental campaigns on a pilot scale. In order to maintain the membrane efficiency and consequently decrease the costs related to the membrane module replacement, it is extremely important to prevent fouling and module damage by the use of effective pre-treatments. This paper concerns with the application of two different membrane technologies in a pilotscale plant as a tertiary treatment of two different textile effluents: ? In the first case study, for a secondary effluent coming from a biological activated plant, a MF step was placed upstream a NF process; ? In the second case study, for a wastewater coming directly from carbonization departments, several treatments, such as clarification, sand filtration and ozonization, were placed as pre-treatment for a UF treatment. The aim of the study was to verify the economical feasibility of the implementation of the membrane processes for the treatment and reuse of textile effluents into productive cycles. 2. Materials and methods 2.1. Textile effluents tested 2.1.1. First case study The wastewater coming from dyeing departments is treated by means of a biological activated sludge plant. Secondary effluents are discharged

M. Marcucci et al. / Desalination 149 (2002) 137–143

139

to surface water in the respect of law limits. The water requirement of the industry is about 1,500 m3/d and it is satisfied with well water. Due to problems of water shortage, it was decided to test new advanced wastewater treatments on the pilot scale in order to reuse textile effluents in manufacturing processes. 2.1.2. Secondary case study The treatment of wastewater coming from a carbonization textile industry has been evaluated. At the present, wastewater coming from productive activities is directly discharged to a municipal depuration plant. The elevated consumption of water used in the carbonization processes (about 2,000 m3/d) and the increase in perspective of the supplying and depuration costs have given a remarkable impulse to start an experimentation on the pilot scale. It has been finalised to work out a specific and innovative treatment in order to recycle a large amount of water (at least 1,000 m3/d). 2.2. Membranes 2.2.1. First case study Microfiltration: a module with two Celgard NADIR P150F spiral-wound membranes placed in series was used for MF. Each membrane was 101.6 mm in diameter and 1,016 mm in length. The total filtrating area of the module was 11 m2. The molecular weight cut-off (MWCO) was 150 kDa. Nanofiltration: an Osmonics Desal DL4040F membrane of the spiral-wound type was used for NF step. The membrane was 98.6 mm in diameter and 1,016 mm in length. The filtrating area was 8.4 m2 and the MWCO was 200 Da. 2.2.2. Second case study Ultrafiltration: a Filterpar FLAMEC filter FF2C.1 CS with flat polyvinyldenefluoride (PVDF) membranes, operating under vacuum, was used.

The total filtrating area of the module was 47 m2. Characteristic molecular weight cut-off was 70,000 Da. 2.3. Pilot plant 2.3.1. First case study The pilot plant consisted of three stages: sand filtration, MF and NF. A part of the effluent from the biological activated sludge plant was sent to the sand filter (2 bar relative pressure). Filtered water was stored in a tank and then sent to the MF module, that operated at a relative pressure of about 3.5 bar. The average MF permeate flow was 400 l/h. The MF effluent was stored in a second tank and sent to the NF module which operated at 6.5–7.0 bar relative pressure. The NF concentrate was 35– 40% of the inlet flow. The MF membranes were automatically washed with the nanofiltration permeate for 30 s every 40 min. The membranes were chemically washed as soon as the hydraulic performance worsened. Chemicals used were: ? Alkaline detergent (1–2%) for removal organic material (fouling); ? Acid detergent (1–2%) for removal inorganic particles (scaling). In a preliminary phase a different treatment was evaluated. It consisted in sand filtration and ozonization, for the treatment of biological effluent in different operative conditions (ozone dosage, contact times between water and ozone). The quality of ozonizated water was not excellent so membrane filtration technologies were tested. 2.3.2. Second case study A part of the wastewater (900 l/h) was treated in a pilot plant composed by: ? A chemical-physical pretreatment, consisting in coagulation, flocculation (at controlled pH condition), settling by means of a lamellar settler and sand filtration;

140

M. Marcucci et al. / Desalination 149 (2002) 137–143

? An ozonization treatment; ? A finishing sand filtration; ? An ultrafiltration.
The high values of turbidity, total suspended solids and COD of the wastewater induced to adopt a complex pretreatment for the UF process (clariflocculation + sand filtration + ozonization). During the trials the definition of the coagulant and the relative optimal dosage were determined. The filtered effluent was sent to an oxidation process in order to remove the organic pollutants and the colour by ozone. It has been necessary to introduce an ultrafiltration treatment after ozonization, because of the presence of a residual turbidity in the ozonized water, imputable to the presence of oxidised compounds. 2.4. Effluents analysis Chemical oxygen demand (COD), pH, conductivity, total hardness, turbidity, total suspended solids (SST), colour, chlorides and surfactants were determined in both experimental campaigns to evaluate the efficiency of the proposed treatments. 2.5. Dyeing tests 2.5.1. First case study Several dyeing tests, using the ozonizated water (first approach) and NF permeate, were carried out on the pilot scale by means of a laboratory machine that dyes 10 g of hank. The dyeing tests were made for dark, medium and light colours on 100% wool. 2.5.2. Second case study The UF permeate was used in dyeing experiments for dark, medium and light colours on the laboratory scale. The fibres used for the tests were wool and cotton. The same tests were carried out on an industrial scale using a 10 kg dyeing machine.

3. Results and discussion 3.1. Membranes hydraulic performance 3.1.1. First case study The working cycle of the both membrane steps, MF and NF, operating under pressure, was monitored for 530 h measuring the permeate flows before and after the cleaning of the membranes with chemical detergents. The characteristic variations with time of MF and NF permeate flowrate and operating pressures are shown in Fig. 1. The dotted lines indicate the interruption of the operating cycle in correspondence of the chemical washing of the membranes (every ~100 h). After the chemical washing, the initial permeate flux is re-established. The MF and NF operating pressures remain nearly constant with the increasing of the membrane fouling.
MF
600
Permeate flow [l/h]

NF
7 6.5 6 5.5 5 4.5 4 3.5 3 300
Pressure [bar]

500 400 300 200 100 0 50 100 150 200 250

Time (h)

Fig. 1. Characteristic MF and NF permeate flow-rate and operating pressures for the first case study.

3.1.2. Second case study The UF membrane process must assure an optimal permeate quality maintaining good performance in terms of permeate flux and operating pressures. The time dependence of the UF operating pressure is shown in Fig. 2. The positive values correspond to the back-washing phase. It can be asserted from the periodic observations of the UF working cycle that:

M. Marcucci et al. / Desalination 149 (2002) 137–143
0. 6

141

Pressure (bar)

0. 4

Table 1 Average values of chemical-physical analyses at the various sampling points, in the first case study
Parameters
0 10 20 30 40 50 60 70 80 90 100 11

0. 2 0 -0. 2 -0. 4

Sampling point 1 2 6.2 62 9 2.4 — 9 5 26 — 100 — — 0 3 6.4 42 <5 0.9 — 8 4 26 — 88 1.1 0.6 13 4 6.1 12 <5 0.5 582 2 2 5 11 78 0.4 0.3 94 6.7 66 21 4.1 1150 9 6 29 260 100 1.1 0.9 Ref.

Time (min)

Fig. 2. Characteristic operating pressure of the FLAMEC FF2C.1 CS UF module in the second case study.

? The absolute value of the UF operating and
back-washing pressure gradually increased and stabilised according with the fouling of the membrane; ? The back-washing started every 30 min even if the absolute value of the operating pressure was almost constant as evidence of the good purification efficiency of the ultrafiltration’s pre-treatment; ? The membranes were never chemically washed since there was not a significant increase of the operating pressure; ? The FLAMEC FF2C.1 CS module guarantees a constant UF permeate flux. 3.2. Contaminants removal 3.2.1. First case study To test the performance of the pilot plant configuration, sampling of the effluents was performed at the following four points: ? Sand filtration inlet; ? Sand filtration outlet; ? Microfiltration permeate outlet; ? Nanofiltration permeate outlet. Table 1 reports the average results of the chemical-physical analyses of the effluents showing the efficiency of the plant system in producing a NF permeate of good quality. The use of sand filtration and of MF is fundamental in the reduction of suspended solids

pH COD, mg/l O2 TSS, mg/l Turbidity, NTU Conductivity, ?s/cm Total hardness, °F Mg2+, mg/l Ca2+, mg/l Sulphates, mg/l Chlorides, mg/l BIASa, mg/l MBASb, mg/l Colourc removal, %
a

Non-ionic surfactants as bismuth-iodine active substances (IRSA method 5160-ISO 7875/2 1st ed., 1984). b Anionic surfactants as methilene blue active substances (IRSA method 5150-ISO 7875/1 1st ed., 1984). c Integral of the absorbance curve in the whole visible range (400–800 nm). d Absorbance at 420 nm.

(100%) and turbidity (78%). COD is removed partially by sand filtration and MF (30%) and quite completely after NF. Colour, one of the most important parameters in checking textile wastewater quality for reuse, is removed almost completely by NF (81%). The histogram in Fig. 3 represents the contributions of the various treatment stages to the total removal of some polluting parameters. The percentages are referred to the sand filter input. 3.2.2. Second case study Sampling of the effluent was performed to test the purification efficiency of the plant configuration. The following sampling points were chosen: Untreated wastewater from carbonization process; ? Ozonization inlet; ? UF inlet; ? UF permeate.

142
sand filter 100 90 80 70 60 50 40 30 20 10 0

M. Marcucci et al. / Desalination 149 (2002) 137–143
MF NF

43%

10%

removal (%)

37%

?
45% 67% 50% 33% 81% 44% 11% 10% 12% 11% 12% 21% 22%

57% 41% 30%

?
13%

6%

Tu

on

C

Fig. 3. Contributions of: a) sand filter; b) microfiltration; c) nanofiltration; to the removal of some parameters. The percentages are referred to the filter input.

To t

al

C hl

ha

? ?

the removal of turbidity (49%), which is of strategic importance for the success of the purification process; High removal of colour (93%), especially by means of the ozonization step (71%); High removal of turbidity (27%) and total suspended solids (30%) by means of UF membrane process; A satisfactory removal of COD (66%); Residual concentration of non-ionic surfactants of 19 mg/l due to high initial concentration.

ity

es

D

ity

ss

BA S

TS S

AS

C O

rb id

iv

ne

id

BI

or

du

rd

M

co l

ct

ou

r

The removal of mean parameters with the last plant configuration (with UF as the advanced treatment) are shown in Fig. 4.
Pretreatment
100 90 80 70 60 50 40 30 20 10 0 35 16 15 49 30 23 38 71 27

Table 2 reports the analytical data concerning the pilot plant configuration with UF as final membrane process. According with the analytical data, the following issues were made evident: ? Good performance of the first stage of the treatment (clariflocculation) concerning with
Table 2 Average values of some parameters at the various sampling points

Ozonization
3 19

UF

30

removal (%)

di ty

ur

.O

rb i

C

Parameters pH COD, mg/l O2 TSS, mg/l Turbidity, NTU Conductivity, ?s/cm Total hardness, °F BIASa, mg/l MBASb, mg/l Colourd removal
a

Sampling point 1 6.9 1017 173 123 2702 — 30.5 2.2 0.092 2 8.9 660 121 63 2938 — 33.1 1.9 0.027 3 7.8 512 56 34 2956 — 20.0 1.3 0.009 4 7.3 352 <5 0.8 2778 25 19.2 0.9 0.007

Fig. 4. Contributions of the three stages of depuration treatment: a) chiariflocculation + sand filtration; b) ozonization; c) ultrafiltration; to the removal of some parameters. The percentages are referred to the pretreatment input.

3.3. Dyeing experiment results 3.3.1. First case study Dyeing experiments with 100% ozonizated water and 100% NF permeate were compared with the same with the softened freshwater. In order to evaluate in a scientific way the results of the laboratory-scale dyeing trials, tests on colour measurement were realised by means of a Gretag Macbeth Coloreye 2180 UV spectrophotometer. They gave different results: ? 100% ozonizated water can be used only in some dyeing steps processes (washing, dyeing

Non-ionic surfactants as bismuth-iodine active substances (IRSA method 5160-ISO 7875/2 1st ed., 1984). b Anionic surfactants as methilene blue active substances (IRSA method 5150-ISO 7875/11th ed., 1984). c Integral of the absorbance curve in the whole visible range (400–800 nm). d Absorbance at 420 nm.

Tu

C

ol o

TS S

.D .

M. Marcucci et al. / Desalination 149 (2002) 137–143

143

with dark colour) or mixed with freshwater;

? 100% NF permeate is reusable in all dyeing
cycle, even for light colours. 3.3.2. Second case study Both the dyeing tests, with 50% UF permeate and 50% well water, on laboratory and industrial scale gave successful results. A comparison among dyeing with freshwater and with a mixed of recycled and well water did not show any differences. 4. Conclusions On the basis of the pilot scale trials results membrane processes show to be promising methods for the purification aimed at reuse of textile wastewater. In the two case studies examined in this work some differences related to the different plantengineering solutions emerge: ? A specific pretreatment for the final membrane stage was studied, because of different characteristics of the textile wastewater: a biological effluent and an untreated carbonization effluent. Nevertheless, in both cases the quality of the effluents is suitable to be reused in all phases of the textile process with the limit of 50% of recycled water in the second case study; ? In both case studies no significant variations in the hydraulic and mechanical parameters of the membrane processes were detected, indicating the efficiency of the pretreatment to reduce membrane fouling. In particular, in the first case study constant values of NF permeate were guaranteed and in the second case study low operating pressures were observed. In consideration of the good results obtained, some economic considerations can be drawn to evaluate the economical feasibility of the imple-

mentation of the membrane processes on the industrial scale. With same wastewater flow of 1,500 m3/d, the unit costs for the two proposed treatments are: ? 0.34 /m3 in the first case study ? 0.40 /m3 in the second case study, which would be a very competitive costs if compared to present costs for water supply and depuration within law limits, guaranteeing a payback of the investment cost of about 3 years.

Acknowledgements The authors are grateful to Fildrop (Firenze, Italy), Filterpar (Bergamo, Italy), Ingrid Ciabatti and Guido Vernaglione for technical support. References
[1] Directive 2000/60/EC of the European Parliament and of the Council of 23 October 2000 establishing a framework for Community action in the field of water policy. Official J. European Communities, No. L 327, 1. [2] M. Marcucci, G. Nosenzo, G. Capanelli, I. Ciabatti, D. Corrieri and G. Ciardelli, Treatment and reuse of textile effluents based on new ultrafiltration and other membrane technologies, Desalination, 138 (2001) 75– 82. [3] A. Lopez et al., Textile wastewater reuse: ozonization of membrane concentrated secondary effluent, Water Sci. Technol., 40(4–5) (1999) 99–105. [4] G. Ciardelli and N. Ranieri, The treatment and reuse of wastewater in the textile industry by means of ozonization and electroflocculation, Water Res., 35(2) (2001) 567–572. [5] A. Rozzi, M. Antonelli and M. Arcari, Membrane treatment of secondary textile effluents for direct reuse, Water Sci. Technol., 40(4–5) (1999) 409–416. [6] A. Bottino, G. Capannelli et al., Membrane processes for textile wastewater treatment aimed at its re-use, In: Proc. 8th World Filtration Congress, Symposium and Exhibition, Brighton, UK, 2000, pp. 521–524.


相关文章:
6A第七单元单词解析
A waste B wasting C throw 7 reuse 【动词】 再利用 reuses reusing reused reuse sth to do sth 再利用某物来做?? water reuse 废水利用,回用水 We can...
水厂生产废水回用方案设计
水厂生产废水回用方案设计 摘要: 某水厂采用滤池反冲洗水直接回收方式进行生产...Production waste water reuse in certain degree water saving, energy saving ...
英语词组答案
useful things 有用的东西 4. use water to clean things 用水洗东西 5. in many places 在许多地方 6. waste water 浪费水 7. reuse and save water 再...
英语作业
MBR is being increasingly used for waste water treatment and water reuse. ...©2015 Baidu 使用百度前必读 | 文库协议 | 网站地图...
6aUnit71
come from, cut down, waste water, reuse, plastic, wood, too much, useful...©2014 Baidu 使用百度前必读 | 文库协议 | 网站地图...
Unit 2 Topic 2 Section A
Collect and reuse waste water .收集、重复使用废水 Unit 2 Topic 2 Section C 1. on earth 在地球上,究竟 millions of 无数的,大量的 during this period ...
九年级英语参考例文
Some factories pour waste water into the rivers ...The three Rs—reduce, reuse and recycle —are ...(10 分) Topic 1 英语是世界上使用最广泛的语言,...
译林版6AU6-U7复习
10. She did shopping on the Internet yesterday afternoon.(用 often 改写...6.waste water 浪费水 7.reuse and save water 再利用及节约水 8.save ...
六年级英语短语
s time for dinner 该吃晚饭了 use rising/falling intonations 用升调/用降调...waste water 浪费水 reuse water 再利用水 save energy 节能 most of our ...
环保部分说明
Table 3-1 Treatment measure, reuse way of wastewater (3x350MW) 表 3-1 废水治理措施、回用方式 Waste water type 废水种类 Domestic sewage of power ...
更多相关标签:
water reuse | campus water reuse | waste water | reuse | so reuseaddr | tcp tw reuse | reuse和recycle的区别 | so reuseaddr的作用 |