Leachate from a composting plant was characterized and applied as a biofertilizer in lettuce crops. Characteristics of untreated (UE) and anaerobically treated (TE) leachate samples were compared. The pH of TE (8.2) increased in relation to the UE (5.2) due to an increase in ammonia nitrogen in TE (1197 mg L-1) compared to UE (859 mg L-1). Anaerobic treatment was efficient in the removal of organic matter from the leachate, evaluated by the decrease of dissolved organic carbon, biochemical oxygen demand, total organic carbon and total solids. K presented the highest concentration (1743 mg L-1) in TE, followed by Mg (135 mg L-1). Cd, Pb and Cr were present at low concentrations in the samples, 0.047, 0.206 and 0.081 mg L-1, respectively. Salmonella, thermotolerant coliforms and viable helminth eggs were not present in TE, which was applied as a biofertilizer in a lettuce crop and compared to mineral fertilization based on fresh matter and dry matter production. Lettuce production using TE was statistically equivalent to mineral fertilization. Toxic metals were not detected in the lettuce shoots. It was concluded that the anaerobically treated leachate from the composting company has the potential to be used as a biofertilizer.

RESUMO Objetivou-se neste trabalho avaliar a remediação de água contendo o inseticida clorpirifós, por meio de sistemas alagados construídos (SAC) cultivados com as espécies Polygonum punctatum, Cynodon spp. e Mentha aquatica operados sob diferentes tempos de retenção hidráulica: 24, 48, 96, 144 e 192 h. A eficiência do sistema foi baseada na redução da concentração inicial do clorpirifós e toxicidade da água contaminada. Os resultados mostraram que os sistemas alagados construídos são uma excelente alternativa na biorremediação do inseticida clorpirifós no meio aquoso. Observou-se média geral de eficiência na remoção do inseticida de 98,6%, sendo que no primeiro tempo de retenção hidráulica, 24 h, houve remoção do clorpirifós para valores inferiores ao limite detecção para todos os SAC. Tal resultado é atribuído principalmente aos processos de adsorção e degradação microbiana. Para os ensaios padronizados qualitativos de toxicidade aguda com Daphnia similis, para a maioria das amostras observou-se a redução de toxicidade acima de 80%. Constatou-se que os testes ecotoxicológicos com os efluentes dos sistemas alagados construídos estudados são uma boa opção como indicativo da eficiência dos tratamentos e uma promissora alternativa na complementação de análises físicas e químicas.

ABSTRACT The objective of this study was to evaluate the remediation of water containing the insecticide chlorpyrifos by using constructed wetlands (CW) cultivated with Polygonum punctatum, Cynodon spp. and Mentha aquatica, operated under different hydraulic retention times: 24, 48, 96, 144 and 192 h. The system efficiency was based on reduction of the initial concentration of chlorpyrifos and toxicity of the contaminated water. The results showed that constructed wetlands are an excellent alternative for remediation of the insecticide chlorpyrifos in aqueous medium. It was observed that the average overall removal efficiency of the insecticide was 98.6%, and in the first hydraulic retention time, 24 h, chlorpyrifos was removed to levels below the detection limit in all CW. This result is mainly attributed to adsorption and microbial degradation. For the qualitative standard acute toxicity tests with Daphnia similis, for most samples there was a reduction in toxicity greater than 80%. It was reported that the ecotoxicological tests with the effluents of the constructed wetland are a good option as an indicator of the effectiveness of treatments and a promising alternative to complement the physical and chemical analyses.

Contaminated irrigation water constitutes one of the main sources of plant pathogens that can cause disease and lead to potentially significant production losses in forest nurseries. Recycling of contaminated irrigation water increases the risk of spreading diseases. The objective of this study was to evaluate a simple slow sand filtration treatment of irrigation water as a method for eradicating fungal and bacterial pathogens in eucalypt cutting nurseries. Pilot filter units were constructed from PVC pipes containing a 80 cm high layer of sand with grain size varying from 0.50 to 0.75 mm, drainage layers of 10 cm of fine gravel (4 mm) followed by a 15 cm layer of coarse gravel (8 mm), connected to a water outlet. The PVC pipe had space for a 150 mm water column above the sand layer and the filter had a flow rate of 100 to 300 L m-2 h-1. Eradication of the bacterial pathogen Ralstonia solanacearum, and the fungal pathogens Cylindrocladium candelabrum and Botrytis cinerea through the use of the filter was evaluated. Detection of bacteria in filter-treated irrigation water was performed through the micro drop method followed by PCR of colonies, while fungal pathogens were detected using a castorbean leaf biological bait method. Evaluations were performed daily 35 times for R. solanacearum, 25 times for C. candelabrum and 18 times for B. cinerea during a period of 12 months. After the last evaluation period, samples from various depths of the sand layer in the filters were taken and analyzed for the presence of the plant pathogens. The slow sand filters were able to remove B. cinerea and C. candelabrum spores with 100% efficiency while eradication of R. solanacearum colonies reached up to 99.6%. Colonies of Trichoderma sp. were found predominantly on the all filter layers. The results of this study show that slow sand filters are efficient for recycled water in eucalypt nurseries, especially in eradicating fungal pathogens.

Neste trabalho, testaram-se 107 rizobactérias, isoladas da rizosfera de mudas de clones de eucalipto, quanto ao seu potencial como promotoras de enraizamento de estacas e miniestacas de eucalipto, em substrato à base de casca de arroz carbonizada e vermiculita (1:1). Estacas e miniestacas foram plantadas em tubetes cônicos contendo substrato tratado e não tratado (testemunha) e foram mantidas sob nebulização intermitente de água a 26-28ºC. Aos 35 dias, avaliou-se a porcentagem média de estacas enraizadas e a massa seca do sistema radicular. Dez isolados destacaram-se como indutores de enraizamento e crescimento, propiciando ganhos de até 110% e de 250%, respectivamente. Esses isolados também foram eficientes no enraizamento de miniestacas, cujos ganhos variaram de acordo com o clone e isolado testado. Os maiores incrementos obtidos no enraizamento de estacas foram superiores aos observados para miniestacas. Em geral, quanto menor o índice de enraizamento do clone, maior foi o ganho médio obtido com a inoculação. Apenas os isolados 3918 (código R98) e MF4 (código R87) foram capazes de produzir ácido indol-acético (AIA) in vitro, em quantidades equivalentes a 0,7 e 0,67 µg/ml de suspensão, respectivamente. Quando comparados ao tratamento de miniestacas em ácido indol butírico (AIB), estes isolados promoveram incrementos significativos na porcentagem de enraizamento e na massa seca do sistema radicular de miniestacas.

A total of 107 rhizobacterial isolates, obtained from the rhizosphere of eucalypt clones were tested as rooting inducers of cuttings and mini-cuttings planted in substrate composed of carbonized rice husk and vermiculite (1:1). Cuttings and mini-cuttings were planted in conical plastic tubes containing treated and untreated (control) substrate and kept under intermittent mist irrigation at 26-28ºC. After 35 days, rooting percentage and dry root matter of cuttings were evaluated. Ten isolates capable of providing gains of up to 110% in root formation and up to 250% in root biomass over non-inoculated control cuttings were selected. Gains in rooting varied according to clone and isolate tested. The greatest gains were obtained for the mini-cuttings exhibiting the lowest rooting efficiency. Among the ten isolates tested, only 3918 (code R98) and MF4 (code R87), produced 3-indole-acetic acid in vitro, at concentrations of 0.7 and 0.67 µg ml-1, respectively. Significant increases in rooting and root dry matter of cuttings grown on rhizobacteria-inoculated substrate were found when compared to untreated or indole-butyric acid (IBA) treated mini-cuttings.