Análise da fitorremediação com Portulaca oleracea L. em um sistema híbrido no tratamento de efluentes agroindustriais de laticínios.

Abstract

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.