Management of biosolids-derived hydrochar (Sewchar): Effect on plant germination, and farmers' acceptance.

Hydrothermal carbonization is a promising approach of biosolids management and its utilization as a soil amendment. This study evaluated the physical and chemical properties of hydrothermally converted biosolids (Sewchar) and its effect as a potential soil amendment on the growth of rice, beans, and radish. The germination experiment was conducted in a greenhouse in a randomized design using five Sewchar doses (0, 10, 20, 40 and 60 Mg ha-1). The results showed that hydrothermal carbonization influences the physicochemical properties of the biosolids, such as promoting pore structure and trace elements below the threshold values for use in agriculture. The spectroscopic techniques demonstrated higher presence of oxygen-containing functional groups (e.g., CO/OH) on surfaces of Sewchar than that of biosolids. The Sewchar doses of 10 Mg ha-1 and 60 Mg ha-1 yielded the highest dry biomass for beans and rice respectively. Increasing Sewchar doses negatively correlated with radish dry biomass, as indicated by linear regression equation fitting (p < 0.05). Thus, biomass responses to Sewchar application into the soil varied with Sewchar dose and type of plant. For a proper environmental management, a survey was conducted to assess farmers' perception and acceptance of Sewchar as a soil amendment. The survey revealed that younger farmers who had higher education qualifications were more prone to use Sewchar as soil amendment. Additionally, farmers who would not use Sewchar as soil amendment attributed the highest level of importance to economic criteria, such as fertilizer and freight prices. In the future, studies on a longer term under field conditions should be performed to elucidate the interactions between Sewchar and soil properties on plant growth and to ensure the safe use of Sewchar as a soil amendment.

Correction to: Effect of biosolid hydrochar on toxicity to earthworms and brine shrimp.

Unfortunately, in the original publication of the article, Prof. Yong Sik Ok's affiliation was incorrectly published. The author's affiliation is as follows.

Organic waste vermicomposting through the addition of rock dust inoculated with domestic sewage wastewater.

The aims of the present study are to assess the organic waste vermicomposting process (cattle manure mixed with tannery sludge) by using inorganic waste (rock dust) inoculated with treated domestic wastewater sewage, as well as the vermicompost application in Ruellia brittoniana seedling production. Different proportions of organic and inorganic waste moistened (or not) in wastewater were vermicomposted (by Eisenia foetida) for 120 days in the first stage of the experiment. Statistically significant earthworm density increase was observed between the 60th and 90th experimental vermicompositing days in all the assessed groups. There was decreased E. foetida population density after 90 days. The K, P, TOC, C/N ratio and Ca, Na and Mg concentrations significantly decreased at the end of the vermicompositing process in comparison to the initial concentrations identified in most treatments. On the other hand, there was pH and N, Fe, Zn and Mn concentration increase in most of the vermicomposts assessed at the end of the experiment. All plants grown in soil containing vermicomposts presented higher Dickson Quality Index (DQI) than the control group, which was cultivated in soil containing commercial topsoil. Plants grown in soil containing 100% cattle manure and tannery sludge, moistened in treated domestic wastewater sewage, showed the highest DQI. Thus, the vermicomposting waste used in the present study, which was inoculated with treated domestic wastewater sewage, is an interesting vermicompost production technology to be used in ornamental plant production.

Effect of biosolid hydrochar on toxicity to earthworms and brine shrimp.

The hydrothermal carbonization of sewage sludge has been studied as an alternative technique for the conversion of sewage sludge into value-added products, such as soil amendments. We tested the toxicity of biosolid hydrochar (Sewchar) to earthworms. Additionally, the toxicity of Sewchar process water filtrate with and without pH adjustment was assessed, using brine shrimps as a model organism. For a Sewchar application of 40 Mg ha-1, the earthworms significantly preferred the side of the vessel with the reference soil (control) over side of the vessel with the Sewchar treatments. There was no acute toxicity of Sewchar to earthworms within the studied concentration range (up to 80 Mg ha-1). Regarding the Sewchar process water filtrate, the median lethal concentration (LC50) to the shrimps was 8.1% for the treatments in which the pH was not adjusted and 54.8% for the treatments in which the pH was adjusted to 8.5. The lethality to the shrimps significantly increased as the amount of Sewchar process water filtrate increased. In the future, specific toxic substances in Sewchar and its process water filtrate, as well as their interactions with soil properties and their impacts on organisms, should be elucidated. Additionally, it should be identified whether the amount of the toxic compounds satisfies the corresponding legal requirements for the safe application of Sewchar and its process water filtrate.

Plant and soil responses to hydrothermally converted sewage sludge (sewchar).

This study compared the effects of sewchar and mineral fertilizer on plant responses in beans (Phaseolus vulgaris, var. "Jalo precoce") and soil properties in a pot experiment in a completely randomized design with two harvests. The initial treatments consisted of a control, sewchar doses of 4, 8, 16 and 32 Mg ha-1 and mineral fertilizer (30 mg N, 90 mg P2O5 and 60 mg K2O kg-1). The treatments (4 replications each) were fertilized with 135 mg P2O5 kg-1 at the second harvest. The sewchar application rates correlated positively with the CEC, the water holding capacity, the availability of Zn, Ca, Fe, Cu, and P, and the concentrations of nitrate, ammonium, total N, total organic carbon and hot water extractable carbon. They correlated negatively with the Mg availability and the soil C: N ratio. Additionally, they correlated positively with the P, Zn and Ca uptake from the soil. For both harvests, the 16 Mg ha-1 sewchar treatment had a total dry matter equivalent to that of the mineral fertilizer. After the second harvest, the 16 Mg ha-1 sewchar treatment revealed 96% higher plant biomass than the control and 79% higher biomass than it did during the first period. The positive effect of sewchar in addition to phosphorous on the plant response and soil properties suggests that the residual effect of sewchar could be a promising alternative as a soil amendment for partly replacing mineral fertilizers. In future, further studies are necessary to evaluate long-term residual effects of sewchar in soil.

Área de preservação permanente em processo de revegetação com espécies arbóreas e adubos verdes / Permanent preservation area revegetated with tree species and green manures

RESUMO O objetivo principal do presente trabalho foi diagnosticar a situação da área em estudo, incluindo o corpo hídrico que é abastecido pelo Córrego Samambaia. Foram realizadas medições de altura e diâmetro das espécies arbóreas, durante 12 meses. Além disso, ocorreram coletas de amostras da água da represa para análise dos parâmetros: pH, condutividade, fósforo total e metais pesados. Nos meses de julho e dezembro de 2014, foram realizadas análises de turbidez, cor, demanda bioquímica de oxigênio (DBO) e oxigênio dissolvido (OD). Foram também realizadas análises físico-químicas do solo. No monitoramento realizado de setembro de 2013 a agosto de 2014, algumas plantas tiveram boa resposta em relação ao uso dos adubos verdes; porém, outras tiveram alta mortandade durante o estudo, como foi o caso do pequi. A competição entre espécies exóticas e nativas foi reduzida, o que aumentou, em geral, a sobrevivência das espécies nativas do bioma do Cerrado. Elementos tais como manganês não apresentaram diferença significativa em todos os tratamentos nos períodos de avaliação. Os valores de macro e microporos foram parecidos, mas a área apresentou diferenças quanto à textura do solo analisado. Quanto aos testes de resistência à penetração (RP) feitos em áreas com e sem adubo verde, os maiores valores foram encontrados na área sem as espécies leguminosas, onde o solo estava mais compactado. Parâmetros como condutividade elétrica da água apresentaram-se estáveis durante os 12 meses de estudo. Os resultados para OD e DBO estão fora do preconizado pela Resolução nº 357 do Conselho Nacional do Meio Ambiente.

ABSTRACT The main objective of this paper was to diagnose the situation of the study area, including the water body that is fueled by Córrego Samambaia. Measurements of height and diameter of tree species were made for 12 months. In addition, dam water samples were collected and the following parameters were analyzed: pH, conductivity, total phosphorus and heavy metals. In July and December of 2014, turbidity, color, biochemical oxygen demand (BOD) and dissolved oxygen (DO) analyzes were made. Physico-chemical analyses of soil were also carried out. Monitoring carried out from September 2013 to August 2014 showed some plants with good response in relation to the use of green manures, but others showed high mortality during the study, as the pequi. The competition between alien and native was reduced, which increased overall survival. Elements such as manganese showed no significant difference in all treatments during evaluation's period. Macro and micropores values were similar, but for texture, the area showed some differences. For penetration resistance tests (PR) made in an area with and without green manure, the largest PR values were found in the one without legumes species. Parameters such as electric conductivity were stable during the 12 months of study. The results for DO and BOD are outside the recommended by the Resolution 357 of the National Environmental Council.

Vermicompostagem de lodo de curtume em associação com esterco bovino utilizando Eisenia fetida / Vermicomposting of tannery sludge mixed with cattle dung using Eisenia fetida

RESUMO O lodo gerado pela indústria curtumeira é um exemplo de resíduo que provoca graves problemas ambientais. Neste sentido, o objetivo do presente estudo foi avaliar a vermicompostagem de lodo de curtume, como método de reaproveitamento desse resíduo. Devido às características tóxicas do lodo de curtume, o mesmo foi misturado com esterco em várias proporções, em base seca. Durante 105 dias, a biomassa e a população das minhocas (Eisenia fetida ) foram avaliadas, além do pH, humidade e temperatura das unidades experimentais estabelecidas. Os substratos foram quimicamente caracterizados no início e no final do processo de vermicompostagem. Nenhuma diferença significativa foi observada em pH nos grupos com menores concentrações de lodo, no entanto, houve uma diminuição significativa no pH nos grupos com maiores concentrações do resíduo durante a vermicompostagem. As concentrações de Mg, Fe, Mn e Zn foram elevadas no vermicompostagem em todos os tratamentos. A relação C/N foi reduzida em todos os tratamentos, indicando o amadurecimento do substrato final. Os resultados indicam que vermicompostagem promove a conversão do lodo em composto em um curto intervalo de tempo, o que constitui um processo biotecnológico de tratamento capaz de adicionar o valor agronômico para este resíduo.

ABSTRACT Tannery industry-generated sludge is an example of residue that causes important environmental problems. In this sense, the objective of the present study was to evaluate vermicomposting of tannery sludge, as a method of treatment this waste. Due to the toxic characteristics of the tannery sludge, it was mixed with cattle dung in various proportions, on dry weight basis. During 105 days, biomass, number of individuals (Eisenia fetida ), pH, moisture and temperature of the experimental units were assessed. The substrates were chemically characterized at the beginning and at the end of the vermicomposting process. No significant differences were observed in pH in groups with lower concentrations of sludge, there was a significant decrease in pH of the groups with higher concentrations of the residue during vermicomposting. Mg, Fe, Mn and Zn contents were high in the vermicompost in all treatments. The C/N ratio was low in the substrate of all treatments, indicating the maturation of the final substrate. The results indicate that vermicomposting promotes the conversion of sludge to manure in a short time interval, thus constituting a biotechnological process of treatment able to add agronomic value to this residue.

Soil microbial biomass and activity in wetlands located in preserved and disturbed environments in the cerrado biome / Biomassa e atividade microbiana do solo em veredas situadas em ambientes conservados e antropizados no bioma cerrado

The veredas (a type of wetlands) are wet ecosystems usually associated with the presence of hydromorphic soils, which often occur in the vicinity of springs and watercourses of the Cerrado region in Brazil. This study aimed to assess microbiological and biochemical soil properties in wetlands (veredas) located in preserved and disturbed environments (in farming and grazing areas) in the Cerrado biome. Soil samples were collected at depths of 0-10 cm and 10-20 cm, along reference lines arranged according to their position in the landscape, in the upper, middle and lower positions of one of the slopes. The total soil organic carbon, microbial biomass carbon and nitrogen (Cmic and Nmic), microbial biomass C:N ratio, microbial quotient, basal respiration, metabolic quotient and fluorescein diacetate (FDA) hydrolytic activities in soil (as total soil heterotrophic enzymatic activity) were determined. The soils of veredas adjacent to agricultural and livestock environments showed changes in their biological properties compared to preserved ecosystems. Increased microbial biomass (Cmic and Nmic) is reported in veredas located nearby grazing areas under intensive and technified management, on the soil surface layer (0-10 cm), especially in the lower slope position, while in agricultural environments, under the same conditions of relief and depth, there is a relative decrease in microbial biomass carbon.

As veredas são ecossistemas úmidos, normalmente associados à presença de solos hidromórficos, que ocorrem com frequência nas proximidades das nascentes e cursos d'água da região do Cerrado. O objetivo deste trabalho foi avaliar atributos microbiológicos e bioquímicos do solo em áreas úmidas (veredas) localizadas em ambientes conservados e antropizados (em áreas agrícolas e pastagens), no bioma Cerrado. Amostras de solo foram coletadas nas profundidades de 0-10 cm e 10-20 cm, ao longo de linhas de referência dispostas, segundo sua posição no relevo, nas posições superior, média e inferior de uma das vertentes. Foram determinados o carbono orgânico total do solo, carbono e nitrogênio da biomassa microbiana (Cmic e Nmic), relação C:N da biomassa microbiana, quociente microbiano, respiração basal, quociente metabólico e atividade enzimática total do solo. Os solos de veredas vizinhas a ambientes agropecuários apresentaram variações em seus atributos biológicos, comparativamente a ecossistemas conservados. Em veredas adjacentes a pastagens sob manejo intensivo tecnificado, na camada superficial do solo (0-10 cm), ocorreu o incremento da biomassa microbiana (Cmic e Nmic), notadamente na posição inferior do relevo, enquanto em ambientes agrícolas, nas mesmas condições de relevo e profundidade, observou-se uma diminuição relativa do carbono da biomassa microbiana.

Teores de micronutrientes nas folhas de milho fertilizadas com lodo de curtume / Contents of micronutrients in the leaves of corn fertilized with tanning mud

A presente pesquisa foi conduzida em vasos em casa de vegetação na Empresa Brasileira de Pesquisa Agropecuária - EMBRAPA-Arroz e Feijão, no município de Santo Antônio de Goiás, GO, nas coordenadas 16 graus 27' de latitude S e 49 graus e 17' de longitude W Gr., e 823 m de altitude. O delineamento experimental utilizado foi inteiramente casualizado, com sete tratamentos e quatro repetições, sendo estes: testemunha, doses de 113,1 ml.vaso-1 de lodo de curtume (36 m3.ha-1)-Lodo36; 226,2 ml.vaso-1 de lodo de curtume (72 m3.ha-1)-Lodo72; 452,4 ml.vaso-1 de lodo de curtume (144 m3.ha-1)-Lodo144; 904,8 ml. vaso-1 de lodo de curtume (288 m3.ha-1)-Lodo288; 1,256 g.vaso-1 do formulado (NPK) 04-30-16 + Zn (400 kg.ha-1)-Químico, e 1,256 g.vaso-1 de (NPK) 04-30-16 + Zn (400 kg.ha-1) + 452,4 ml.vaso-1 de lodo de curtume (144 m3.ha-1)-Lodo 144 + Qu?mico. As análises químicas do solo (substrato) foram realizadas nas camadas de 0-20 cm e de 20-40 cm. Foi quantificada a fitomassa verde da parte aérea, e os teores de cobre, ferro, manganês e zinco. Nas folhas das plantas de milho, o cobre, em todos os tratamentos com lodo de curtume e com adubação química, manteve seus teores próximos dos teores da testemunha. O teor de ferro do tratamento Químico foi maior e significativamente diferente dos teores dos demais tratamentos. O comportamento do manganês, nos diferentes tratamentos, não seguiu um padrão definido, tendo sido constatado maior teor deste elemento no tratamento Lodo72, que diferiu estatisticamente dos demais. Com relação ao elemento zinco, o maior teor encontrado nas folhas foi no tratamento Lodo144 + Químico, que diferiu estatisticamente dos demais tratamentos analisados. Nos tratamentos onde foi aplicadosomente o lodo de curtume, a produção de fitomassa verde das plantas de milho tendeu a ser crescente com as doses do lodo. A adubação química associada ao lodo de curtume (Lodo144 + Químico) proporcionou a maior produção de fitomassa verde de plantas de milho.

This investigation aimed to study the accumulation of micronutrients in the leaves of corn plants fertilized with tanning mud. Therefor an experiment in pot culture was conducted in a greenhouse of the Empresa Brasileira de Pesquisa Agropecuária (Embrapa-Arroz e Feijão) located at 16 graus e 27' latitude S, 49 graus e 17' longitude W Gr. And 823 m above sea level, in the county of Santo Antônio de Goiás, GO. The experimental design was completely randomized in four replications and the following treatments: Control, tanning mud at 113.1 ml pot-1 (36 m3 ha-1) = Mud-36; tanning mud at 226.2 ml pot-1 (72 m3 ha-1) = Mud-72; tanning mud at 452.4 ml pot-1 (144 m3 ha-1) = Mud-144; tanning mud at 904.8 ml pot-1 (288 m3 ha-1) = Mud-288; mineral fertilizer at 1.256 g pot-1 of NPK 04-30-16 plus Zn (400 kg ha-1) = Chemical; and Mud- 144 plus Chemical. The chemical soil analysis was accomplished in two layers, 0-20 cm and 20-40 cm. Further were analyzes the contents of copper, iron, manganese and zinc in the green matter. There was no significant difference in copper content among treatments. The treatment Chemical showed significantly higher content in iron than all others. Mud-72 was significantly superior to all other treatments in manganese content. The highest content of zinc was found in treatment Mud-144 plus Chemical, superior to all others. The yield of green matter tended to grow with increasing levels of tanning mud but the highest yield was found in treatment Mud-144 plus Chemical.