ANDRADE, S. O.; SILVA, OSVALDO S. DA.; http://lattes.cnpq.br/0846389166580231; ANDRADE, Sanduel Oliveira de.
Résumé:
The volume of effluent generated by family agro-industries has grown in recent decades due to
the resurgence of this sector and if they are released into the environment without proper treat-
ment, it can cause several negative impacts. A barrier to the treatment of these effluents are the
costs of implementing conventional treatment plants. Thus, it becomes important to develop
technologies that are efficient and of low cost for the small rural producer. In this context, this
research evaluated a hybrid system, composed of a biodigester in series with Constructed Wet-
ted Systems, for the treatment of agro-industrial effluent from dairy products. The research was
carried out at the Federal University of Campina Grande, Campus Pombal, and consisted of
four stages: 1) Construction, operation and monitoring of beds vegetated with Portulaca
oleracea L. irrigated with saline solutions; 2) Construction, operation and monitoring of a CW
laboratory-scale; 3) Construction, operation and monitoring of two hybrid systems formed by
biodigesters in series with CWs, one with vegetation and the other without; 4) Construction,
operation and monitoring of a hybrid system formed by a biodigester in series with a CW field-
scale. In the first stage, the species Portulaca oleracea L. was submitted to six concentrations
of NaCl, monitoring its development through indicators such as fresh mass, dry mass and ash.
In the second stage, the raw effluent was sent directly to the CW cultivated with Portulaca
oleracea L., in laboratory scale, performing only the removal of coarse materials. In the third
stage, on a laboratory scale, a biodigester was inserted to attenuate the organic concentration of
the effluent directed to CW. The first bed was cultivated with the species Eichhornia crassipes
M. due to the behavior of Portulaca oleracea L. in the second stage. At this stage, a second CW
was made without the vegetation cover, using only the soil and gravel substrates. Stage 4, on a
field scale, consisted of a biodigester, a CW cultivated with Eichhornia crassipes M. and a CW
with Portulaca oleracea L. In step 1, Portulaca oleracea L. showed moderate tolerance to sa-
line environments. In step 2, it was found that there was a reduction in the metabolism of Por-
tulaca oleracea L. when submitted directly to the raw effluent, despite reducing parameters
such as turbidity and COD. The cattle manure present in the beds interfered negatively in the
final result, increasing the levels of electrical conductivity, NKT and P(tot), being suppressed
from the CWs in stages 3 and 4. In stage 3, the influence of vegetation on the treatment was
observed, considerably reducing BOD, COD, NKT and P(tot). In step 4, the system showed more
satisfactory results, reducing turbidity, BOD and COD by more than 90%. However, the biogas
production was unsatisfactory, not generating sufficient quantities for storage and burning. Fi-
nally, the biodigester system in series with the CWs proved to be efficient in removing the
organic load in dairy effluents and combined with the low cost of installation and maintenance,
it can be indicated for installation in small family agribusinesses.