Heavy metals availability and soil fertility after land application of sewage sludge on dystroferric Red Latosol

Abstract

Sewage sludge is the solid residue obtained from urban sewage treatment plants. It is possible to use the sludge in a sustainable way as fertilizer and as soil conditioner due to its high levels of organic matter and nutrients. Besides pathogens and volatile organic compounds, the residue may also contain heavy metals which may accumulate and contaminate crops and the food chain. The aim of this study was evaluates the changes in the fertility of dystrophic Red Latosol and in the availability of heavy metals following application of sewage sludge. It was assessed whether organic matter supplied to the soil as large amounts of sewage sludge would decrease availability of heavy metals in the soil due to of insoluble compounds formation. From this, an experiment was carried out in polyethylene pots using lettuce plant for test. Sewage sludge were applied to the soil in concentrations equivalent to 60, 120 and 180 t ha -1 , and a control without sludge, in four replicates, in a completely randomized design. The results show that sewage sludge led to an increase of organic matter contents, of the cation exchange capacity (CEC) and of nutrients found in the soil. It also improved plant growth up to a concentration of 120 t ha -1 . Availability of heavy metals, however, was reduced in sludge concentrations starting with 120 t ha -1 .Index terms: Biosolids, soil pollution, nutrients, Lactuca sativa. RESUMOLodo de esgoto é o resíduo obtido após o tratamento dos esgotos municipais. Em decorrência dos elevados teores de matéria orgânica e de nutrientes, é possível utilizar o lodo, de forma sustentável, como fertilizante agrícola e condicionador de solos. Todavia, além de patógenos e de compostos orgânicos voláteis, esse resíduo pode conter ainda metais pesados que podem ser acumulados e contaminar as culturas agrícolas e a cadeia trófica. Assim, neste trabalho, objetivou-se avaliar as alterações na fertilidade de um Latossolo Vermelho distrófico e na disponibilidade de metais pesados decorrentes da aplicação de lodo de esgoto. Foi avaliado se a matéria orgânica fornecida ao solo com aplicações elevadas de lodo deverá, em razão da formação de compostos insolúveis, diminuir a disponibilidade dos metais pesados do solo. Para tanto, foi conduzido experimento em vasos de polietileno, com a aplicação do lodo no solo nas concentrações equivalentes a 60, 120 e 180 t ha -1 , e um tratamento controle sem lodo, com quatro repetições, em delineamento inteiramente casualizado, utilizando alface como planta teste. Os resultados indicam que o lodo de esgoto promoveu o aumento dos teores de matéria orgânica, da capacidade de troca catiônica (CTC) e de nutrientes no solo e ainda melhorou o desenvolvimento das plantas até a concentração de 120 t ha -1 . A disponibilidade dos metais pesados, no entanto, foi reduzida nos tratamentos a partir de 120 t ha -1 de lodo.Termos para indexação: Biossólidos, poluição do solo, nutrientes, Lactuca sativa.

The Possibility of Organo-Mineral Fertilizer Production from Sewage Sludge

“…The ratio of Cd content increase is higher than those for Pb, Cu and Zn [41][42][43]. Wang and co-worker indicated that the addition of 40 t of sewage sludge per ha in rice production resulted in the build-up of about 4, 5, 2, and 11 times more of Cd, Cr, Ni and Pb, respectively, in comparison with non-treated soil.…”

Nutritional status and physiological parameters of maize cultivated with sewage sludge

“…Although the increase of the SS rates promoted an increment of Zn in the soil (Table 5), the SS2 treatment presented higher Zn content in the leaves (Figure 2). This result can be explained by the increase in soil organic matter content, which can complex this element, reducing its availability to plants (Moreira;Mincato;Santos, 2013).…”

“…Another factor that limits the use of SS in agriculture is the risk of soil and food contamination by heavy metals (Abreu-Junior et al, 2019;Moreira;Mincato;Santos, 2013). Some metals are essential nutrients required in small contents by the plants.…”

Nodulation, nitrogen uptake and growth of lima bean in a composted tannery sludge-treated soil

“…Also, LOPEZ-LUNA et al (2012) have shown an accumulation of Cr in the shoot of common bean with the application of tannery sludge. In general, Cr uptake by the plants accumulates in the roots and forms barriers that diminish their translocation to the shoot (MOREIRA et al, 2013). The biological N fixation, being a process carried out at the root level, can be influenced by the excessive presence of Cr due to the alteration of the biochemical processes of the microorganisms and direct toxicity on Bradyrizobium (HUNGRIA & VARGAS, 2000) and rhizobia symbiosis (STAMBULSKA et al, 2018).…”