**2. Assessment of waste water quality**

*Electrodialysis*

(**Figures 1** and **2**) between 10.450

per SWID, Govt. of West Bengal survey.

effluent treatment plant with zero liquid discharge system through implementation of membrane based ultra-filtration, reverse osmosis with recourse to recycling of bleaching and dying effluent at Kalikapur, West Bengal, India to save groundwater, environment and human health of a thickly populated area and 15 KM from Calcutta, a premier city of India. It revealed during study that the contamination level of surface water including canal water running in the cluster is highly contaminated. The waste water discharged into the nearby canal water is the main source of contamination as most of the units do not treat the waste water due to lack of treatment facilities in their own. The soil profile of the area is also degraded in the locality. Hence, the only way left behind is to treat the waste water to a level which can be reused in textile units through recycling. Membrane based treatment of waste water is found suitable in this circumstances to treat the toxic waste water as well as recycling of the treated water to the textile units to save groundwater paucity of the area. The water requirement in these industries is very high compare to any other industries in the world. The area Maheshtala, Chatta, Kalikapur, Mahishgot lie in South 24 Parganas district of West Bengal

N latitude to 75.900

than 1400 small and tiny bleaching and dying units as per Economic Survey (2014), Govt. of West Bengal where groundwater table is shrinking day by day as

E longitude having more

**80**

**Figure 2.**

**Figure 1.**

*Map of Maheshtala region.*

*Map of Chatta Kalikapur.*

The overall mean concentrations of different physico-chemical parameters studied (pH, TDS, BOD, COD, NO3, hardness, Fe, F, Pb, Cd, Cr and Na) showed distinct seasonal trend in the following order of variation: pre-monsoon (April, May and June) > monsoon (July, August September and October) > post-monsoon (November, December, January and February)(P < 0.05). The physicochemical profile of waste water reflects that highest concentrations of both metals and organic loading are associated with the quantum and quality of bleaching and dyeing effluents released from the units studied. For the Maheshtala textile units the manufacturing processes like cutting and stitching activities of cloths start in the pre-monsoon season whereas the bleaching and dyeing processes starts in June continues till August stretching pre-monsoon to monsoon to meet the demand in festival season, which have significant implications in both metal and organic loading in the wastewater effluents. The present findings on high metal concentration and deteriorated physicochemical parameters are similar in other studies on textile industries waste water [1–3].

There appeared significant differences in metal concentrations in wastewater reflected in the following order: Na > Fe > Cr > Pb > Cd (P < 0.05). The metals in wastewater find their sources in the chemicals (like sodium hydrochlorides, sodium hydro-sulphites, optical brightening agent, caustic soda etc.) and dyes (mordant dyes, azo dyes, disperse dyes, vat dyes, indigo dyes etc.) used for the wet processing of textiles.

The heavy metal pollution index (HPI) for the wastewater studied is estimated as 926 which exceeds the critical level of 100 for drinking water as determined by Hakanson model [4] by about 9 folds. The study has shown similar HPI value for water of Jamuna river (near Delhi) obtained by [5, 6] following the same model (1492). Again the metal index (MI) in case of the studied wastewater is 4.68 which far exceeds than that of the threshold level of 1 for drinking water as prescribed by Hakanson model [4]. While assessing the water quality index (WQI) the results show that the wastewater poses severe potential ecological/health risk during all the seasons being maximum threat (WQI PRM-16) followed by (WQI M-19) and the minimum in post-monsoon (WQI PSM-31). According to Hakanson model (in the scale of 0–100) the present risk falls under the severe category in pre-monsoon and monsoon and critical in post monsoon with an annual average WQI being 22.

While comparing with the permissible limits for relevant parameters in case of wastewater discharge as per IS: 10500 (2012) it was observed that the values of the physico-chemical parameters and metals in the present study exceeded the respective limits.

All the physico-chemical parameters and metal concentrations in wastewater are very much higher than the permissible limits for drinking water of BS: 10500 (2012) and WHO (2003). These indicate that wastewater is critically contaminated compared to limits provided for drinking water. It finds conformity with observations of [7]. Due to higher level of TSS, TDS, BOD, COD and presence of very high concentrations of Pb, Fe and Na the wastewater becomes highly contaminated and often toxic, and there remains high chance of transfer of metals to soils and subsequently to crops, vegetables and fruits when irrigation contamination occurs due to advertent irrigation or inadvertent flooding of agricultural fields [8]. Wastewater also contaminates the water ways due to its direct discharge to the Chatta canal and damage aquatic ecosystem of canal, pond, watershed and ground water due to infiltration as shown by similar study conducted by [9].

Statistical correlation matrix shows that there is a significant positive correlation (r = 0.60) of Cd with TDS. Sodium has significant positive correlation with TSS (r = 0.78) and Fe (r = 0.56) and negative correlation with fluoride (r = −0.87).

### **3. Assessment of quality of canal water**

The overall mean data of different physicochemical parameters of canal water indicate that TSS, TDS, BOD, COD, CaCO3, Na, Pb, Cd and Cr are higher than their permissible limits for drinking water prescribed by IS: 10500 (2012) and WHO (2003).

There appears a distinct seasonal trend in BOD, COD and metal concentrations in canal water in the following order of variation: PSM > M > PRM (P < 0.05). This finding can be explained by the fact that as the manufacturing as well as bleachingdyeing activities become more intense during November and December to meet the demands of the Christmas and Ramjan festivals compared to the B and D activities in monsoon for meeting the demands of puja festive season the quantity of wastewater in the former becomes greater inclusive of its metal and organic load. Their concentrations fall during pre-monsoon due to reduced production and concomitant effluent discharge load.

There appeared significant differences in metal concentrations in canal water reflected in the following order: Na > Fe > Pb > Cr > Cd (P < 0.05). The metals in wastewater find their sources in the chemicals like sodium hydrochlorides, sodium hydro-sulphites, optical brightening agent, caustic soda etc. and dyes (mordant dyes, azo dyes, disperse dyes, vat dyes, indigo dyes etc.) used for the wet processing of textiles.

Further the overall mean values in mg/L of TSS (37), TDS (2150), BOD (60), COD (293), Na (669), metals (Pb, Cd and Cr) specify the canal water is very much contaminated similar to observations made by [10]. TDS in canal water appears due to presence of mostly dissolved inorganic salts (principally calcium, magnesium, potassium, sodium, bicarbonates, chlorides and sulfates) and partly contributed by small amounts of organic matter dissolved in water [11].

The heavy metal pollution index (HPI) estimated for the canal water is 689 which has far exceeded (about 7 fold) the critical pollution value of 100 as per Hakanson model [4]. The metal index (MI) for canal water has been calculated as 6.90 which is about 7 times the critical pollution value considering all the metals present as per Hakanson model [4]. The water quality index (WQI) for canal water indicates that there appears potential ecological/health risk during PRM (49), M (39) and PSM (28) indicating severe water quality in pre-monsoon and monsoon, and critically deteriorated condition of water quality during post-monsoon season as per Hakanson model [4].

The high values of COD and BOD are attributed to the organic loading and oxidizable matter present in wasterwater discharged from the B&D units coming to the canal water and its mixing with the sewage coming from neighboring region. The very low level of dissolved oxygen (1.7 mg/L) is indicative of oxygen deficiency in the canal water which appears to be detrimental for sustenance of biota excepting a few indicator species [12]. During monsoon season as the canal overflows the canal water contaminates adjoining agricultural fields, it contaminates them due to presence of metals like Pb, Cd, Cr, Fe and Na. Such build-up of contaminants has serious adverse implications for severe contamination of the fields being almost agriculturally nonproductive; even the vegetables and fruits grown in selected residents of that area were found heavily laden with metals. The presence of total coliforms and fecal coliform indicates that the canal water was microbiologically

**83**

**5.1 pH**

value from 0 to 14.

**5.2 Turbidity**

*Toxic Effluent Treatment by Membrane Based Ultrafiltration and Reverse Osmosis…*

contamination of surface water due to textile industries [14–21].

contaminated, which may have their genesis from contamination of B&D wastewater with domestic sewage and fecal matters. The canal water can pollute the ground water due to presence of metals (Pb, Cd, Cr, Fe and Na) and inorganic chemicals due to long term infiltration [13]. These findings are similar in other studies on

The statistical correlation analyses show that COD has significant positive correlation with BOD (r = 0.98). Na has significant strong positive correlation with BOD (r = 0.91) and COD (r = 0.98) while Cr has positive correlation with Na (r = 0.47). Again nitrate has significant positive correlation with BOD (r = 0.91), Na (r = 0.73)

The overall mean data of different metals and chemical parameters of soil indicate that Pb, Cr, Cd, Zn, Fe, NO3 are higher than the permissible limit of WHO (1996). The heavy metal concentrations in soil show the pattern in the following order: Zn > Pb > Cr > Fe > Cd (P < 0.05). These indicate that soil is contaminated with metals and not suitable for agricultural production [22]. The metal index for soil has been estimated as 336, which far exceeds the critical pollution value of 100 as per Hakanson model [4]. The soil quality index (SQI) indicates that it poses a potential ecological/health risk as reflected from its value (519), which is about five time the value of critical condition i.e. >100 due to presence of toxic metals. Among the metals highest ecologically risk is posed due to Cr and Pb followed by moderate risk from Zn and slight risk due to Cd. Considering the relative heavy metal concentrations in the canal water and soil the heavy metal concentration factors for different metals show the highest concentration in case of Cr (2325) followed by Pb (314) and Cd (44.24). Such metal concentrations in soil in course of time get transferred to vegetables and fruits grown in the locality and pose severe health risks to humans [23]. These results can be corroborated with the findings of several other studies [24–27]. Statistical correlations show that Cr is positively correlated with nitrate (NO3) (r = 0.57) while

Bleaching and dyeing units consume major quantities of water in textile industries, is the third largest user of water in the world. Wet processing is one of the major one in textile engineering. In all stages of wet processing large amount of water is used. Soft water is the major requirement of wet processing in textile

pH is the reference point of H+ ions concentration, its quantity indicates the quality of water,such as neutral, acidic or alkaline. .pH of neutral at 7, less than 7 indicates acidic and alkaline when above 7. The pH measurement scale is having

Turbidity is reason by the scattering of light by suspended substance which may be organic or inorganic in universe. The turbidity of water is calculated against a

**5. Some important parameters of water for textile processing**

standard solution having a standard turbidity value 1000 units.

*DOI: http://dx.doi.org/10.5772/intechopen.92812*

and negative correlation with pH (r = −0.45).

and F is negatively correlated with NO3 (r = −0.49).

industries for leading production quality.

**4. Assessment of quality of soil**

*Toxic Effluent Treatment by Membrane Based Ultrafiltration and Reverse Osmosis… DOI: http://dx.doi.org/10.5772/intechopen.92812*

contaminated, which may have their genesis from contamination of B&D wastewater with domestic sewage and fecal matters. The canal water can pollute the ground water due to presence of metals (Pb, Cd, Cr, Fe and Na) and inorganic chemicals due to long term infiltration [13]. These findings are similar in other studies on contamination of surface water due to textile industries [14–21].

The statistical correlation analyses show that COD has significant positive correlation with BOD (r = 0.98). Na has significant strong positive correlation with BOD (r = 0.91) and COD (r = 0.98) while Cr has positive correlation with Na (r = 0.47). Again nitrate has significant positive correlation with BOD (r = 0.91), Na (r = 0.73) and negative correlation with pH (r = −0.45).

#### **4. Assessment of quality of soil**

*Electrodialysis*

(2003).

of textiles.

tant effluent discharge load.

as per Hakanson model [4].

Statistical correlation matrix shows that there is a significant positive correlation

The overall mean data of different physicochemical parameters of canal water indicate that TSS, TDS, BOD, COD, CaCO3, Na, Pb, Cd and Cr are higher than their permissible limits for drinking water prescribed by IS: 10500 (2012) and WHO

There appears a distinct seasonal trend in BOD, COD and metal concentrations in canal water in the following order of variation: PSM > M > PRM (P < 0.05). This finding can be explained by the fact that as the manufacturing as well as bleachingdyeing activities become more intense during November and December to meet the demands of the Christmas and Ramjan festivals compared to the B and D activities in monsoon for meeting the demands of puja festive season the quantity of wastewater in the former becomes greater inclusive of its metal and organic load. Their concentrations fall during pre-monsoon due to reduced production and concomi-

There appeared significant differences in metal concentrations in canal water reflected in the following order: Na > Fe > Pb > Cr > Cd (P < 0.05). The metals in wastewater find their sources in the chemicals like sodium hydrochlorides, sodium hydro-sulphites, optical brightening agent, caustic soda etc. and dyes (mordant dyes, azo dyes, disperse dyes, vat dyes, indigo dyes etc.) used for the wet processing

Further the overall mean values in mg/L of TSS (37), TDS (2150), BOD (60), COD (293), Na (669), metals (Pb, Cd and Cr) specify the canal water is very much contaminated similar to observations made by [10]. TDS in canal water appears due to presence of mostly dissolved inorganic salts (principally calcium, magnesium, potassium, sodium, bicarbonates, chlorides and sulfates) and partly contributed by

The heavy metal pollution index (HPI) estimated for the canal water is 689 which has far exceeded (about 7 fold) the critical pollution value of 100 as per Hakanson model [4]. The metal index (MI) for canal water has been calculated as 6.90 which is about 7 times the critical pollution value considering all the metals present as per Hakanson model [4]. The water quality index (WQI) for canal water indicates that there appears potential ecological/health risk during PRM (49), M (39) and PSM (28) indicating severe water quality in pre-monsoon and monsoon, and critically deteriorated condition of water quality during post-monsoon season

The high values of COD and BOD are attributed to the organic loading and oxidizable matter present in wasterwater discharged from the B&D units coming to the canal water and its mixing with the sewage coming from neighboring region. The very low level of dissolved oxygen (1.7 mg/L) is indicative of oxygen deficiency in the canal water which appears to be detrimental for sustenance of biota excepting a few indicator species [12]. During monsoon season as the canal overflows the canal water contaminates adjoining agricultural fields, it contaminates them due to presence of metals like Pb, Cd, Cr, Fe and Na. Such build-up of contaminants has serious adverse implications for severe contamination of the fields being almost agriculturally nonproductive; even the vegetables and fruits grown in selected residents of that area were found heavily laden with metals. The presence of total coliforms and fecal coliform indicates that the canal water was microbiologically

small amounts of organic matter dissolved in water [11].

(r = 0.60) of Cd with TDS. Sodium has significant positive correlation with TSS (r = 0.78) and Fe (r = 0.56) and negative correlation with fluoride (r = −0.87).

**3. Assessment of quality of canal water**

**82**

The overall mean data of different metals and chemical parameters of soil indicate that Pb, Cr, Cd, Zn, Fe, NO3 are higher than the permissible limit of WHO (1996). The heavy metal concentrations in soil show the pattern in the following order: Zn > Pb > Cr > Fe > Cd (P < 0.05). These indicate that soil is contaminated with metals and not suitable for agricultural production [22]. The metal index for soil has been estimated as 336, which far exceeds the critical pollution value of 100 as per Hakanson model [4]. The soil quality index (SQI) indicates that it poses a potential ecological/health risk as reflected from its value (519), which is about five time the value of critical condition i.e. >100 due to presence of toxic metals. Among the metals highest ecologically risk is posed due to Cr and Pb followed by moderate risk from Zn and slight risk due to Cd. Considering the relative heavy metal concentrations in the canal water and soil the heavy metal concentration factors for different metals show the highest concentration in case of Cr (2325) followed by Pb (314) and Cd (44.24). Such metal concentrations in soil in course of time get transferred to vegetables and fruits grown in the locality and pose severe health risks to humans [23]. These results can be corroborated with the findings of several other studies [24–27]. Statistical correlations show that Cr is positively correlated with nitrate (NO3) (r = 0.57) while and F is negatively correlated with NO3 (r = −0.49).

Bleaching and dyeing units consume major quantities of water in textile industries, is the third largest user of water in the world. Wet processing is one of the major one in textile engineering. In all stages of wet processing large amount of water is used. Soft water is the major requirement of wet processing in textile industries for leading production quality.

### **5. Some important parameters of water for textile processing**

#### **5.1 pH**

pH is the reference point of H+ ions concentration, its quantity indicates the quality of water,such as neutral, acidic or alkaline. .pH of neutral at 7, less than 7 indicates acidic and alkaline when above 7. The pH measurement scale is having value from 0 to 14.

#### **5.2 Turbidity**

Turbidity is reason by the scattering of light by suspended substance which may be organic or inorganic in universe. The turbidity of water is calculated against a standard solution having a standard turbidity value 1000 units.

## **5.3 Color**

Color normally shows the presence of suspended and soluble matter, which affects the wet processing. The Hazen unit is the measurement of color of water and is comparing it with a color of a standard water solution. A colored Hazen unit is produced by liquefaction 1 ppm platinum in the form of chloroplatinic acid, in the impression of 2 ppm cobalt chloride.
