**4.2.5 WWTP-E**

Among all pesticides analyzed in the effluent of the WWTP-E, only dimethoate was detected. The concentration of this pesticide in this effluent was 0.272 μg L-1. According to these results, the concentrations of detected pesticides in the 5 studied effluents are from 0.02 μg L-1 to more than 1 μg L-1. This interval of concentrations is similar to ones detected in other WWTPs by other researches (Kastsoyiannis and Samara 2004; Muñoz et al., 2008). Moreover, after this study a direct relation between detected pesticides in the effluents and treatments carried out in each WWTP hasn't been observed.

#### **4.3 Application in reclamation**

According to the Spanish Royal Decree 1620/2007, water must guarantee quality criteria in order to it can be reused. These criteria change in function of the use of water. Maximum admissible values of enteric nematodes, Escherichia coli, turbidity and suspended solids as well as other criteria related to other pollutants.

In accordance with the presence of hazardous substance, among them, pesticides, EQSs established in the Directive 2008/105/EC (Directive 2008/105/EC) and in the Spanish Royal Decree 60/2011 (Royal Decree 60/2011) must be respected.

This study, about the application of effluents of WWTPs in reclamation, has been carried out not taking into account microbiological parameters. Next, the possible application of studied waters in reclamation is showed. This application has been divided in two parts: on one hand, taking into account values of turbidity and suspended solids in the law; and on other hand, the presence of pesticides.

#### **4.3.1 Application in reclamation: turbidity and suspended solids**

As it has been mentioned previously, in the annex I of Royal Decree 1620/2007 maximum admissible values of suspended solids and turbidity are indicated in order to reuse water and depending on its use. These values are shown in the table 6. In accordance with these values and the values obtained to the effluents of studied WWTPs, some conclusions can be extracted:


According to the obtained results of suspended solids concentration and turbidity, this water cannot be applied in any use without an additional treatment. It would be needed a treatment capable to decrease, as a minimum, suspended solids in water in order to apply it in some agricultural, industrial, recreational and environmental uses. They are:

Study of the Presence of Pesticides in Treated Urban Wastewaters 465

to some agricultural, industrial, recreational and environmental uses:

reclaimed water and fruits consumed in the human diet.

direct contact between reclaimed water and productions.

• Recharge of aquifers by located percolation by the ground.

the turbidity, it is necessary decrease suspended solids in water.

cereals and oleaginous seeds.

cooling towers and evaporative condensers.

cereals and oleaginous seeds.

• Other industrial uses.

is impeded.

• Silviculture.



could be applied as is to:

later.

• Aqueaculture.

• Irrigation of pastures to consumption of animals producing milk or meat.

• Process and cleaning water in the alimentary and no alimentary industry.

requires a posterior treatment if is destined to other uses. This water can be reused as is

• Irrigation of products to human consumption with a system of water application which doesn't avoid the direct contact between reclaimed water and comestible parts and their consumption isn't in fresh form but with an industrial treatment later.

• Located irrigation of woody cultivation which impedes the contact between the

• Irrigation of cultivation of ornamental flowers, nurseries, greenhouses without

• Irrigation of non alimentary industrial cultivation, nurseries, ensilaged forages,

• Ponds, water masses and ornamental circulated flows in which the access of people

• Irrigation of forests, green places and of other type which isn't accessible to people.

In the case of urban uses it is necessary decrease the turbidity of water, just like to use in irrigation of golf courses and recharge of aquifers by direct injection. Its use in cooling towers and evaporative condensers is the only case in which, as well as reduce

In view of characteristics of this water with regard to suspended solids and turbidity, this water could be used without applying it any additional treatment to all uses practically. Only it would be necessary an additional treatment which was capable to reduce suspended solids and turbidity of water in the case of one industrial use, in

In this case, this water could be used in some sectors without applying any treatment and it would require an additional treatment in order to use in other uses. This water

• Irrigation of products to human consumption with a system of water application which doesn't avoid the direct contact between reclaimed water and comestible parts and their consumption isn't in fresh form but with an industrial treatment

• Located irrigation of woody cultivation which impedes the contact between the

• Irrigation of cultivation of ornamental flowers, nurseries, greenhouses without

• Irrigation of non alimentary industrial cultivation, nurseries, ensilaged forages,

• Irrigation of pastures to consumption of animals producing milk or meat.

reclaimed water and fruits consumed in the human diet.

direct contact between reclaimed water and productions.

• Process and cleaning water in the alimentary industry.


Table 6. Maximum admissible values of suspended solids and turbidity to reclaimed waters (Royal Decree 1620/2007)


As well as to apply a treatment capable to reduce the suspended solids concentration in water, it would be needed to reduce the turbidity too in order to apply this water in urban uses and the rest of uses contemplated and no mentioned previously. - WWTP-B:

According to the obtained results of suspended solids concentration and turbidity, this water can be reused without applying any additional treatment to some uses and it requires a posterior treatment if is destined to other uses. This water can be reused as is to some agricultural, industrial, recreational and environmental uses:


In the case of urban uses it is necessary decrease the turbidity of water, just like to use in irrigation of golf courses and recharge of aquifers by direct injection. Its use in cooling towers and evaporative condensers is the only case in which, as well as reduce the turbidity, it is necessary decrease suspended solids in water.


464 Pesticides in the Modern World - Risks and Benefits

USE OF WATER SUSPENDED SOLIDS

Quality 1.1 10 2 URBAN USES Quality 1.2 20 10

Quality 2.2 35 - AGRICULTURAL

INDUSTRIAL USES Quality 3.1 (c) 35 -

RECREATIONAL Quality 4.1 20 10 USES Quality 4.2 35 -

Quality 5.3 35 - ENVIRONMENTAL

Table 6. Maximum admissible values of suspended solids and turbidity to reclaimed waters

• Irrigation of pastures to consumption of animals producing milk or meat.

reclaimed water and fruits consumed in the human diet.

direct contact between reclaimed water and productions.

• Process and cleaning water in the alimentary industry.

• Recharge of aquifers by located percolation by the ground.

cereals and oleaginous seeds.

• Irrigation of products to human consumption with a system of water application which doesn't avoid the direct contact between reclaimed water and comestible parts and their consumption isn't in fresh form but with an industrial treatment

• Located irrigation of woody cultivation which impedes the contact between the

• Irrigation of cultivation of ornamental flowers, nurseries, greenhouses without

• Irrigation of non alimentary industrial cultivation, nurseries, ensilaged forages,

• Ponds, water masses and ornamental circulated flows in which the access of people

• Irrigation of forests, green places and of other type which isn't accessible to people.

As well as to apply a treatment capable to reduce the suspended solids concentration in water, it would be needed to reduce the turbidity too in order to apply this water in

According to the obtained results of suspended solids concentration and turbidity, this water can be reused without applying any additional treatment to some uses and it

urban uses and the rest of uses contemplated and no mentioned previously.

USES

USES

(Royal Decree 1620/2007)

later.

is impeded.

• Silviculture.


MAXIMUM ADMISSIBLE VALUE

TURBIDITY (NTU)

(mg L-1)

Quality 2.1 20 10

Quality 2.3 35 - Quality 3.1 (a and b) 35 15

Quality 3.2 5 1

Quality 5.1 35 - Quality 5.2 10 2

Quality 5.4 Minimum required quality will be studied

in each case

In view of characteristics of this water with regard to suspended solids and turbidity, this water could be used without applying it any additional treatment to all uses practically. Only it would be necessary an additional treatment which was capable to reduce suspended solids and turbidity of water in the case of one industrial use, in cooling towers and evaporative condensers.


In this case, this water could be used in some sectors without applying any treatment and it would require an additional treatment in order to use in other uses. This water could be applied as is to:


Study of the Presence of Pesticides in Treated Urban Wastewaters 467

Due to the presence of pesticides this water couldn't be reused without applying an

Detected concentrations of terbuthylazine and isoproturon exceed the maximum admissible concentrations indicated in the current legislation, therefore it is necessary to apply a treatment capable to degrade partially these pesticides in order to reuse this water. In this water, prometon is detected too but to this pesticide, an EQS isn't

The effluent of this WWTP could be reused without any additional treatment taking

In this water, only chlorpyrifos is detected but its concentration doesn't exceed the

In the case of this WWTP, the water couldn't be reused as is therefore an additional

The addtional treatment had to reduce the concentration of terbuthylazine of the water because detected concentration of this pesticide exceedes the corresponding EQS. In this water other pesticides are detected, chlorfenvinfos, simazine and dimethoathe. However, detected concentration of chlorfenfinfos and simazine don't exceed the EQSs

Regarding to the presence of pesticides, this water could be reused without treating it

In this effluent, some pesticides are detected by in any case the EQSs are exceeded or there aren't EQSs indicated in the legislation to these pesticides. 3,4-dichloroaniline, terbutryn and metholaclor are detected but these pesticides aren't comtemplated in the EQSs of the legistación. Terbuthylazina is detected too, but the detected concentration

Only dimethoathe is detected in this WWTP effluent but this pesticide isn't considered




doesn't exceed the maximum admissible concentration legislated.

After carrying out this study, some conclusions can be extracted. With respect to the presence of pesticides in effluents of WWTPs:

heptachlor, heptachlor epoxide B, pp'-DDD and pp'-DDE.

This effluent could be reused as is with respect to the presence of pesticides.


indicated. - WWTP-B:




**5. Conclusions** 

simazine.

previously.

additional treatment.

into account the presence of pesticides.

treatment would be necessary for this.

and for dimethote, any EQS is established.

in the EQSs in the current legislation.

from water, such as pesticides.

maximum admissible one indicated in the legislation.


In order to reuse the water to the rest of uses could be necessary to apply a treatment capable to reduce the turbidity and suspended solids up to limits established in current legislation, except to its industrial use as process and cleaning water in the alimentary and no alimentary industrial for which only a reduction of the turbidity of water would be necessary.


With respect to the effluent of the last selected WWTP, this could be used without an additonal treatment to the most of contemplated uses: urban, agricultural, industrial, recreational and environmental. Only a subsequent treatment, capable to reduce the turbidity and suspended solids, would be necessary in order to apply this water in the next uses:

