**4.2 Presence of pesticides in effluents of WWTPs**

In general, in effluents of selected WWTPs exists the presence of several pesticides. Among all analyzed pesticides, 10 different pesticides have been detected: chlorfenvinfos, chlorpyrifos, dimethoate, isoproturon, prometon, metholachlor, 3,4-dichloroaniline, terbutryn, terbuthylazine and simazine. Chemical structures of detected pesticides in studied effluents are shown in the figure 6.

As it has been mentioned previously, the characterization of WWTPs effluents is carried out by several physical-chemical parameters, among them, turbidity and suspended solids concentration, which are parameters whose maximum admissible values are indicated in the Spanish legislation related to water reclamation (Royal Decree 1620/2007). Characterization

> **WWTP-B**

pH (temperature in ºC) 7.6 (14.7) 7.9(15.8) 7.4(11.1) 7.2(18.6) 7.3(13.5) Conductivity (μS cm-1) 3220 1867 1086 2950 832 Turbidity (NTU) 34.0 12.3 1.7 34.7 5.4

concentration (mg L-1) 56 8 4 32 20

(mg L-1) 84 60 77 62 50

5-days (mg L-1) 16.4 17.5 15.3 15.5 12.5

As well as this characterization, a bibliographic study was carried out. This study was done in order to confirm that the results of the selected WWTPs obtained are between typical values regarding characteristics of WWTPs effluents. In accordance with this study, habitual values of analyzed parameters in WWTPs effluents are shown in the table 5 (Imai et al., 2002; Mendoça

In accordance with the obtained results it can be observed that the characterization values of

Suspended solids concentration (mg L-1) 4 – 92 Chemical Oxygen Demand (mg L-1) 19 – 98 Oxygen Biological Demand 5-days (mg L-1) 5 – 31 Table 5. Usual values of physical-chemical parameters in WWTPs effluents according to

In general, in effluents of selected WWTPs exists the presence of several pesticides. Among all analyzed pesticides, 10 different pesticides have been detected: chlorfenvinfos, chlorpyrifos, dimethoate, isoproturon, prometon, metholachlor, 3,4-dichloroaniline, terbutryn, terbuthylazine and simazine. Chemical structures of detected pesticides in

**Parameter Interval**  pH 7 – 8

Conductivity (μS cm-1) 70 – 3200 Turbidity (NTU) 3 – 52

**WWTP-C** 

**WWTP-D** 

**WWTP-E** 

**A** 

et al., 2007; Hassanli et al., 2008; Kalavrouziotis et al., 2009; Santos et al., 2009).

the selected effluents are within usual intervals to effluents of WWTPs.

**4.1 Characterization of effluents of selected WWTPs** 

results of WWTPs effluents are shown in the table 4.

**Parameter WWTP-**

Table 4. Results of the characterization of studied effluents

**4.2 Presence of pesticides in effluents of WWTPs** 

studied effluents are shown in the figure 6.

Suspended solids

Chemical Oxygen Demand

Oxygen Biological Demand

other references

**4. Results** 

Fig. 6. Chemical structures of detected pesticides in effluents of studied WWTPs

Detected pesticides belong to different groups.

In the first place, organic-phosphorous pesticides such as chlorfenvinfos, chlopyrifos and dimethoate are detected. These pesticides are mainly used as insecticides. Chlorpyrifos and dimethoate are very toxic and chlorfenvinfos is extremely toxic. The main effects in the health caused by these pesticides are irritation of eyes and skin and if the exposition to these pesticides is long-term they can affect to nervous, respiratory and immunological systems.

Pesticides derived of urea such as isoproturon and diuron are detected too. These pesticides are mainly used as herbicides and they are moderately toxic compounds. They can cause irritation of skin, eyes and respiratory system, in addition to blood alterations in the case of extend expositions.

Some of detected pesticides belong to triazines group; they are terbutryn, terbuthylazine and simazine. These pesticides are mainly used as herbicides and they are moderately toxic substances. With respect to effects on health, the can cause irritation in eyes and skin and moreover, affections in liver, kidney, nervous and circulatory systems in the case of longterm contact.

Finally, the rest of detected pesticides are metholachlor and 3,4-dichloroaniline. Metholachlor belongs to anilide group, it is a moderately toxic substance and used as herbicide. It can cause irritation in eyes and in the case of long-term exposition it can provoke liver and blood conditions. 3.4-dichloroaniline is used as herbicide and it is a moderately toxic pesticide. It can cause dermatitis and damages in liver and kidney after long-term expositions.

Some of the pesticides detected in the studied effluents, such as chlorpyrifos, chlorfenvinfos, isoproturon and simazine were detected in other effluents of WWTPs such as it is shown in

Study of the Presence of Pesticides in Treated Urban Wastewaters 463

Among all pesticides analyzed in the effluent of the WWTP-D, 4 pesticides were detected: 3,4-dichloroaniline, terbutryn, terbuthylazine and metholachlor. Detected concentrations of

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

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

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

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

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:



**4.3 Application in reclamation** 

hand, the presence of pesticides.


treatments carried out in each WWTP hasn't been observed.

Decree 60/2011 (Royal Decree 60/2011) must be respected.

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

well as other criteria related to other pollutants.

**4.2.4 WWTP-D** 

**4.2.5 WWTP-E** 

these pesticides were:


other research works. As well as these pesticides, in these studies other pesticides were detected: α-endosulphan, hexachlorociclohexanes (α, β, χ, δ), atrazine, diuron, hexachlorobenzene, endrin, dieldrin, heptachlor, heptachlor epoxide B, pp'-DDD and pp'- DDE (Kastsoyiannis and Samara, 2004; Muñoz et al., 2008). Chemical structures of theses pesticides are shown in the figure 7.

Fig. 7. Chemical structures of pesticides detected in other effluents of WWTPs (Kastsoyiannis and Samara, 2004; Muñoz et al., 2008)

Next, detected pesticides and their concentrations in studied effluents of each WWTP are detailed.

#### **4.2.1 WWTP-A**

Among all analyzed pesticides in the effluent of the WWTP-A, 3 pesticides were detected: prometon, terbuthylazine and isoproturon. Detected concentrations of these pesticides were:

