poster - International Conference of Agricultural Engineering

extractable and non-extractable bound residues plays an important role in the destination of
pesticides in the soil in the long term.
Accordingly, this study aims at quantifying desorption, extractable and bound residues
of alachlor in swine wastewater (SWW) treated soil, in dissolved and total forms, from two
effluent treatment systems and subjected to tests of miscible displacement. Moreover, this
work also aimed at determining the percentage of extractable residues of alachlor according
to solvents used for extraction.
2. Materials and Methods
Tested treatments included: Control: no addition of SWW, MOD-B: dissolved organic
matter from SWW treated in biodigester, MOT-B: total organic matter from SWW treated in
biodigester; MOD-E: dissolved organic matter from SWW treated in lagoon treatments, and,
MOT-E: total organic matter from SWW treated in lagoon treatments.
The SWWs were collected from two farms that have piglet production system. One of
the properties has integrated biosystem for the treatment of pig manure, and the collection
was conducted at the point where the effluent leaves the biodigester, because most of the
properties that work with pig manure in biodigesters do not perform the other treatment steps
provided in the integrated biosystem. The SWW from lagoon treatments was collected in
another farm that treats swine waste in a sequence of three lagoon treatments. The
collection was conducted at the output of the third lagoon effluent.
The MOT consisted of SWW just as it was collected, and the MOD was extracted from
SWW according to an adaptation of the methodology described by Zhaohai et al. (2008). In
the extraction of MOD, centrifugation and filtration methods were used. Initially, centrifugation
at 3200 rpm (2474 g) was performed for 15 minutes, and then the supernatant was filtered
through a membrane of cellulose acetate of 0.45 mm in porosity. After filtration, the material
was frozen. The main physical and chemical characteristics of SWW treated in biodigester
and lagoon treatments in dissolved and total form, can be found in Table 1.
TABLE 1: Swine wastewater characterization
Parameters Unit MOT-B MOD-B MOT-E MOD-E
pH (CaCl2) - 7.15 8.27 7.20 8.07
Electric conductivity µS cm -1 6,810.00 5,820.00 6990.00 6270.00
Oxigen chemical demand
4,830.00 1,539.00 2154.00 1405.00
Total nitrogen
mg L -1 1,190.00 905.30 967.90 863.30
Total solids 3,860.00 2510.00 3193.00 2104.00
Total organic carbon (TOC) 967.00 355.60 547.30 255.40
Fixed solids 2,106.00 1674.00 2129.00 1457.00
Volatile solids 1,755.00 837.00 1064.00 647.00
Protocol of APHA, AWWA and WEF (1998). Total organic carbon (TOC) was determined by TOC analyzer.
The soil (Oxisol, according to EMBRAPA, 2006) was collected in forest area, in order to
ensure no soil contamination by alachlor and other pesticides. Collection depth was 30-60
cm to eliminate the effect of organic matter resulting from litter. This soil consists of 10.87%
sand, 12.32% silt and 76.81% clay. The pH is 4.25, the organic matter content is 17 g dm -3 ,
CEC is 151 mmol c dm -3 and the concentration of total nitrogen is 467 mg dm -3 .
It was used the alachlor (2-chloro-2,6-diethyl-N-(methoxymethyl acetamide)), an
herbicide from the chloroacetamide group, analytical grade (Pestanal ® ), with water solubility
of 172 mg L -1 .
Quantification was performed using the high-performance liquid chromatography
(HPLC) technique in Shimadzu ® , Prominence chromatograph. The samples were filtered
through a membrane of 0.45 mm pore size, and injected into the chromatograph at the
following conditions: C-18 column (150 x 4.6 mm), mobile phase acetonitrile: water (60:40, v
/ v) Detector UV - 220 nm, continuous flow of 1 mL min -1 , oven temperature of 35 °C, and
injection volume of 20 µL (Silva & Vieira 2009; Sopeña et al., 2009).