Different stages of microbial community during the anaerobic digestion of food waste.

Large-scale food waste (FW) disposal has resulted in severe environmental degradation and financial losses around the world. Although FW has a high biomass energy contents and a growing large number of national projects to recover energy from FW by anaerobic digestion (AD) are being developed. AD is a promising solution for FW management and energy generation when compared to typical disposal options including landfill disposal, incineration, and composting. AD of FW can be combined with an existing AD operation or linked to the manufacture of value-added products to reduce costs and increase income. AD is a metabolic process that requires four different types of microbes: hydrolyzers, acidogens, acetogens, and methanogens. Microbes use a variety of strategies to avoid difficult situations in the AD, such as competition for the same substrate between sulfate-reducing bacteria and methane-forming bacteria. An improved comprehension of the microbiology involved in the anaerobic digestion of FW will provide new insight into the circumstances needed to maximize this procedure, including its possibilities for use in co-digestion mechanisms. This paper reviewed the present scientific knowledge of microbial community during the AD and the connection between microbial diversity during the AD of FW.

Microplastic pollution and the related ecological risks of organic composts from different raw materials.

Organic composts are considered emerging contributors to microplastics (MPs) accumulation in agricultural soils. However, MPs pollution in organic compost from different raw materials is unknown. This study investigated MPs occurrence and characteristics in 124 organic compost samples, including single feedstock (livestock manure, poultry manure, crop straw, and solid waste) and compound organic composts, and quantitatively assessed related ecological risks of MPs pollution. The highest and lowest MPs abundances were observed in solid waste (6615 items kg-1) and crop straw (1500 items kg-1) composts, respectively. Compost MPs were mainly 0.5-1 mm (39.5%), colorful polypropylene and polyethylene fragments and films, and polyethylene terephthalate fibers, and the input to farmland soils was 6.96 × 107 to 1.88 × 108 items ha-1 yr-1. Regardless of feedstock, compost-based MPs of different shapes exhibited complicated weathering morphologies and adhered to some mineral colloids. The highest and lowest MPs-induced risk indices in solid waste (H = 134.3) and crop straw (H = 8.9) composts yielded hazard levels IV (high risk) and II (low risk), respectively, due to the different abundance of polymers with diverse hazard scores. These findings provide insights into MPs pollution in organic composts and a theoretical basis for the safe production and application of compost.

ICT-based solution for efficient fecal sludge management: An experience from Bangladesh.

In Bangladesh, people primarily depend on on-site sanitation facilities (OSSF) with an immense challenge in achieving safe sanitation due to unplanned infrastructure development, improper management of fecal sludge, and inadequate monitoring. The commitment of attaining Sustainable Development Goals (SDG) 6.2 (ensuring safe sanitation for all) by 2030 requires immediate attention in the management of fecal sludge for low-middle income countries. This paper presented the findings, challenges, and possible ways forward from a study conducted to provide data for Information and Communication Technology (ICT)-based fecal sludge management (FSM) at a municipality in the northwest of Bangladesh. A total of 18,808 households and 407 institutions in Saidpur municipality, a non-sewered town in Nilphamari district, were studied to understand the type of containment structures and on-ground desludging practices. The study showed around 10% of containments were connected to the drains illegally, 95% of the people in Saidpur practiced unsafe disposal, and 7% still practiced open defecation. To identify these malpractices, the study also implemented an ICT-based sustainable solution through a web application that enabled the local administrator to have a global look at the sanitation scenario of the municipality. The dashboard was developed to create a total sanitation monitoring system, identify defaulters, allow target-based safe managed sanitation service strategies, and ensure sustainability in FSM. The study highlighted the accessibility of vacuum truck services projecting through a spatial map and identified methods to empty the septic tanks where Vacutag services are unavailable by engaging local pit emptiers. The innovative approach of fecal sludge management will help not only to improve the existing sanitation practices but also raise community awareness to ensure sustainable sanitation system. Altogether, the web system will work as a medium to manage the faecal sludge for the existing co-compost plant where the faeces is converted into organic soil conditioner, creating prospects for a green business mechanism.

Spatio-temporal variation of soil microplastics as emerging pollutant after long-term application of plastic mulching and organic compost in apple orchards.

Microplastics (MPs) pollution in agroecosystems have aroused great alarm and widespread concern. However, the spatial distribution and temporal variation characteristics of MPs in apple orchards with long-term plastic mulching and organic compost input are still poorly understood. This study investigated MPs accumulation characteristics and vertical distribution after applying plastic mulch and organic compost in apple orchards for 3 (AO-3), 9 (AO-9), 17 (AO-17), and 26 (AO-26) years on the Loess Plateau. The clear tillage (no plastic mulching and organic composts) area was used as a control (CK). At a soil depth of 0-40 cm, AO-3, AO-9, AO-17, and AO-26 treatments increased the abundances of MPs, and the black fibers and fragments of rayon and polypropylene were dominant. In the 0-20 cm soil layer, the abundances of MPs increased with the treatment time; the abundance was 4333 pieces kg-1 after 26 years of treatment, gradually decreasing with soil depth. In different treatments and soil layers, the percentages of MPs <1000 µm were dominant (>50%). The AO-17 and AO-26 treatments significantly increased the MPs with the size of 0-500 µm at 0-40 cm and the abundances of pellets in 0-60 cm soil. In conclusion, the long-term (≥17 years) application of plastic mulching and organic composts increased the abundances of small particles at 0-40 cm, and plastic mulching contributed the most to MPs, while organic composts increased the complexity and diversity of MPs.

Does the initial C/N ratio interfere with the performance of sewage sludge composting and cotton waste?

The effects of the initial C/N ratio on the composting of sewage sludge and cotton residues are not reported in the literature. Understanding the main composting control parameters is essential for the good stabilization of these wastes. Therefore, this study sought to evaluate different initial C/N ratios for the composting of sewage sludge and cotton waste, aiming to find the ranges with the best performance for the process and quality of the final organic compost. In this sense, five mixtures of sewage sludge (S) and cotton residues (C) were prepared and composted with three replications for each treatment in a completely randomized design. Physicochemical parameters were evaluated during composting and in the final organic compounds. A Multivariate Principal Component Analysis (PCA) was applied to evaluate the agronomic quality of organic compounds. The thermal behaviour of the mixtures presented differences. The treatments 90C10S, 80C20S and 67C33S showed the highest EXI² index (3566.64, 3448.39 and 2738.89), longer duration of thermophilic phase (12 and 13 days) and better potential for maximum degradation (A) of organic matter (67.5, 61.2 and 65.6%C). The final compounds of 90C10S and 80C20S showed higher pH values (7.9 and 7.5) and higher CEC (123.6 and 114.0 meq/100 g OM). PCA showed similarity in the agronomic quality of organic compounds for 90C10S, 80C20S and 67C33S. The treatment 28C72S (initial C/N ratio of 16.6) presented final pH of 5.3 and did not meet the minimum limit required by Brazilian regulations. Initial C/N relations between 24.9 and 35.2 showed better stabilization of waste and final organic compound with better agronomic quality.

Medium-Term Effects of Sprinkler Irrigation Combined with a Single Compost Application on Water and Rice Productivity and Food Safety.

Traditional rice (Oryza sativa L.) management (tillage and flooding) is unsustainable due to soil degradation and the large amount of irrigation water used, an issue which is exacerbated in the Mediterranean region. Therefore, there is a need to explore rice management strategies in order to improve water-use efficiency and ensure its sustainability. Thus, field experiments were conducted to determine the medium-term effects of different irrigation and tillage methods combined with a single compost application on water and rice productivity, as well as food safety in a semiarid Mediterranean region. The management systems evaluated were: sprinkler irrigation in combination with no-tillage (SNT), sprinkler irrigation in combination with conventional tillage (ST), which were implemented in 2015, and flooding irrigation in combination with conventional tillage (FT), and their homologues (SNT-C, ST-C, and FT-C) with single compost application in 2015. In reference to rice grain yield, the highest values were observed under ST treatment with 10 307 and 11 625 kg ha-1 in 2018 and 2019 respectively; whereas between FT and SNT there were no significant differences, with 8 140 kg ha-1 as mean value through the study. Nevertheless, sprinkler irrigation allowed saving 55% of the total amount of water applied in reference to flooding irrigation. Furthermore, the highest arsenic concentration in grains was found under FT but it decreased with compost application (FT-C) and especially with sprinkler irrigation, regardless of tillage management systems. However, sprinkler irrigation favors the cadmium uptake by plants, although this process was reduced under SNT in reference to ST, and especially under amended compost treatments. Therefore, our results suggested that a combination of sprinkler irrigation and compost application, regardless of the tillage system, could be an excellent strategy for rice management for the Mediterranean environment in terms of water and crop productivity as well as food safety.

Root response and phosphorus uptake with enhancement in available phosphorus level in soil in the presence of water-soluble organic matter deriving from organic material.

Understanding the available phosphorus (P) levels in the presence of water-soluble organic matter (WSOM) deriving from organic materials can be important for the improvement of the P use efficiency. This study aimed to: (i) determine which types of WSOM (deriving from the organic material) can suppress P immobilization, and (ii) understand whether plants can uptake P that the immobilization is suppressed by the presence of WSOM, as well as how the plant roots response depending on the available P levels. The P sorption test revealed that the presence of WSOM deriving from cattle manure compost (CM), sewage sludge compost (SSC), and hydrothermal decomposed liquid fertilizer (HDLF) can suppress the P sorption by 44, 44, and 24%, respectively, as compared to single P. In the incubation test, the percentage of the available P to that added as P fertilizer was found to be >21% higher in the presence of a CM- or a SSC-derived WSOM than those of single P, but the effect of the HDLF-derived WSOM was not. In the cultivation test, P uptake was found to be improved in the CM-, the SSC-, and the HDLF-deriving WSOM by 17, 13, and 11%, respectively, as compared to single P. Moreover, the root weight was found to decrease along with an increase in the amount of P uptaken by the plant. These findings provide the first experimental evidence that the presence of the WSOM deriving from CM, SSC, and HDLF simultaneously enhance the available P level in the soil and P uptake by the plant at the lab-scale test. In addition, the higher the available P levels in the presence of WSOM, the lower the root developments. The presence of WSOM, particularly of one of high maturity, can suppress the P sorption by 24-44%; as a result, >20% of the P added remains as the available P depending on the type of organic material used.

Additions of optimum water, spent mushroom compost and wood biochar to improve the growth performance of Althaea rosea in drought-prone coal-mined spoils.

Ecosystem degradation as a result of coal mining is a common phenomenon in various regions of the world, especially in arid and semi-arid zones. The implementation of appropriate revegetation techniques can be considered crucial to restore these degraded areas. In this regard, the additions of spent mushroom compost (SMC) and wood biochar (WB) to infertile and degraded soils have been reported to enhance soil fertility and plant growth under water (W) deficit conditions. However, the combined application of W, SMC and WB to coal mine degraded soils, to promote Althaea rosea growth and facilitate subsequent restoration, has not been explored yet. Hence, in the current study a pot experiment was carried out by growing A. rosea on coal mine spoils to assess the influence of different doses of W, SMC and WB on its morpho-physiological and biochemical growth responses. The results indicated that several plant growth traits like plant height, root length and dry biomass significantly improved with moderate W-SMC-WB doses. In addition, the simultaneous application of W-SMC-WB caused a significant decrease in hydrogen peroxide (H2O2) (by 7-56%), superoxide anion (O2●‒) (by 14-51%), malondialdehyde (MDA) (by 23-46%) and proline (Pro) contents (by 23-66%), as well as an increase in relative water content (by 10-27%), membrane stability index (by 2-24%), net photosynthesis rate (by 40-99%), total chlorophylls (by 43-113%) and carotenoids (by 31-115%), as compared to the control treatment. The addition of SMC and WB under low-W regime enhanced leaf water use efficiency, and soluble sugar content, also boosting the activity of superoxide dismutase, catalase, peroxidase and ascorbate peroxidase in leaf tissues, thus reducing the oxidative stress, as proved by low levels of H2O2, O2●‒, MDA and Pro contents. Finest growth performance under optimum doses of W (60% field capacity), SMC (1.4%) and WB (0.8%) suggest that revegetation of A. rosea with the recommended W-SMC-WB doses would be a suitable and eco-friendly approach for ecological restoration in arid degraded areas.

Soil fungal community affected by regional climate played an important role in the decomposition of organic compost.

A large amount of organic compost, produced with agricultural and breeding industry wastes by composting, is widely used in agriculture in China. The microbial decomposition of organic compost is a major flux in the nutrition cycle in sustainable agricultural soils. To explore the mechanism of organic compost mineralization in soil, in situ decomposition experiments of organic compost buried in soils were arranged in three different latitude regions located in Jilin, Jiangsu, and Yunnan in China. The results showed that organic compost had different decomposition rates at the three different sites, with the highest decomposition rate in Yunnan, followed by Jiangsu and Jilin. The decomposition rates of unsterilized organic compost were significantly greater than those of sterilized organic compost, indicating that the microorganisms in organic compost also made important contributions to the decomposition process. The soil microbial diversity and community structure among the three sites were significantly different. The fungal community, especially fungal richness, rather than the bacterial community in the soil, plays a major role in the decomposition of organic compost. The annual average temperature is an important environmental factor affecting fungal richness. This study will provide a reference for formulating agricultural fertilization models in different regions.

Agricultural residues as substrates in the production of formosa papaya, okra and zucchini seedlings / Resíduos agrícolas como substratos na produção de mudas de mamão formosa, abóbora e quiabo

Using residues generated in agriculture to produce seedlings is an economically interesting alternative, besides being a way to reduce the environmental impacts caused by their inadequate disposal. This study aimed to evaluate the potential of using coffee chaff (CC) and organic compost (OC) as substrate components for the production of Formosa papaya seedlings and the potential of grape pomace (GP), a vitiviniculture residue, in the composition of substrates for the production of okra and zucchini seedlings. We carried out two trials in a completely randomized design (CRD): the first had seven treatments and six replicates: T0: 100% commercial substrate Bioplant® (CS); from T1 to T6: increasing proportions of CC and decreasing of CC: 10/90; 20/80; 30/70; 40/60; 50/50 e 60/40%. The second had six treatments and six replicates, with increasing proportions of GP and decreasing proportions of CS: 0/100; 10/90; 20/80; 30/70; 40/60 and 50/50%.In the first trial we evaluated the number of leaves, root length, seedling height, stem diameter, shoot dry mass, root dry mass, total dry mass and Dickson Quality Index (DQI) at 59 days after sowing. The second trial was performed at 12 and 18 DAS and we analyzed the number of leaves, plant height, root length, collar diameter, shoot dry mass, root dry mass, total dry mass and Dickson Quality Index (DQI). Variables that met the assumptions of normality and homoscedasticity were subjected to Dunnett's test. The substrate composed of coffee chaff and organic compost has a high potential to be used as an alternative substrate due to promote better quality of papaya seedlings compared to the commercial substrate. Alternative substrate containing 60% coffee chaff and 40% organic compost is recommended for the production of Formosa papaya seedlings in tubes. The grape pomace (GP) has a high potential to be used as component in substrate for the production of okra and zucchini seedlings compared to the commercial substrate (CS) only. Alternative substrate composed of 50% GP and 50% CS is recommended for the production of zucchini seedlings, while substrate composed of 10% GP and 90% CS is recommended for the production of okra seedlings.

A utilização de resíduos advindos da agricultura apresenta-se como uma alternativa interessante do ponto de vista econômico, para a obtenção de mudas, além de ser uma forma de diminuir os impactos ambientais causados pelo descarte inadequado destes resíduos no ambiente. Objetivou-se avaliar a potencialidade de utilização da moinha de café e composto orgânico como componentes de substratos para produção de mudas de mamão Formosa, e a potencialidade dos resíduos da vitivinicultura como componentes de substratos para produção de mudas de abóbora e quiabo. Na produção de mudas de mamão formosa, o experimento foi realizado no delineamento inteiramente casualizado (DIC), com sete tratamentos e seis repetições, sendo: T0 = 100% de substrato comercial Bioplant® (SC), e do T1 ao T6, proporções crescentes de moinha de café (MC) e decrescentes de composto orgânico (CO): 10/90; 20/80; 30/70; 40/60; 50/50 e 60/40%. Na produção de mudas de abóbora e quiabo, o experimento foi realizado no delineamento inteiramente casualizado (DIC), com seis tratamentos e seis repetições, sendo proporções crescentes de bagaço de uva (BU) e decrescentes de substrato comercial (SC): 0/100; 10/90; 20/80; 30/70; 40/60 e 50/50%. Aos 59 DAS foram avaliados o número de folhas, altura da muda, diâmetro do caule, massa de matéria seca da parte aérea, radicular e total da muda e o Índice de Qualidade de Dickson (IQD) em mudas de mamão formosa. As avaliações nas mudas de abóbora e quiabo foram realizadas aos 12 e 18 DAS, respectivamente, e as variáveis analisadas foram o número de folhas, altura da planta, comprimento da raiz, diâmetro do coleto, massa seca da parte aérea, massa seca da raiz, massa seca total e o IQD. O substrato composto por moinha de café e composto orgânico possui elevado potencial de uso em razão de promover melhor qualidade de mudas de mamoeiro quando comparado com o substrato comercial. Recomenda-se o substrato alternativo contendo 60% de moinha de café e 40% de composto orgânico, em substituição ao substrato convencional, na produção de mudas de mamão Formosa em tubetes. O bagaço de uva possui elevado potencial para ser usado como componente de substrato na produção de mudas de abóbora e quiabo quando comparado com o uso isolado do substrato comercial. Para produção de mudas de abóbora recomenda-se o uso do substrato composto por 50% de BU e 50% de SC, já para a produção de mudas de quiabo recomenda-se um substrato composto por 10% de BU e 90% de SC.

Effect of organic compost and inorganic nitrogen fertigation on spinach growth, phytochemical accumulation and antioxidant activity.

The aim of this study was to evaluate the effect of the addition of organic compost in combination with the inorganic nitrogen fertigation on growth, phytochemical accumulation, and antioxidant activity of spinach (Spinacia oleracea L. cv. Manatee). Soil blocked spinach seedlings (six seedlings per block), three blocks per pot (316 plants m-2) were transplanted after 18 days after emergence into to 12 L pots. The treatments were: unfertilized soil, organic compost, organic compost +75 kg of N ha-1, applied as ammonium sulfate; and organic compost +75 kg N ha-1, applied as ammonium nitrate. The addition of organic compost to unfertilized soil increased the fresh yield. The application of inorganic N from the two sources in relation to organic compost treatment increased spinach fresh yield from 2.3 to 4.81 kg m-2 and shoot dry weight from 0.60 to 1,31 g plant-1. Levels of carotenoids also increased with inorganic N addition, producing higher values in plants grown with organic compost + ammonium nitrate (31.14 mg/100 g fresh weight). However, the addition of N led to a decrease in leaf-blade total phenols from 75 to 56 mg gallic acid equivalents/100mg fresh weight. The addition of inorganic N led to a dramatic decrease in leaf-blade ferric reducing antioxidant activity. This effect was higher with ammonium sulfate application. The application of organic compost and inorganic nitrogen had no influence on the petiole's phytochemical accumulation and antioxidant activity.

Composted slaughterhouse sludge as a substitute for chemical fertilizers in the cultures of lettuce (Lactuca sativa L.) and radish (Raphanus sativus L.)

Abstract Flotation sludge (FS) is produced in huge amounts at slaughterhouses in western Santa Catarina, Brazil. This waste is rich in plant nutrients and a valuable resource for soil amendments. Five FS composts were tested as a replacement for chemical fertilizers (QF), namely T1 (75% poultry manure (PM) and 25% sawdust (SD)); T2 (50% PM and 50% SD); T3 (25% PM and 75% SD); T4 (100% PM and 0% SD); and T5 (0% PM x 100% SD). For lettuce plants, treatments containing composted FS resulted in an increased number of leaves, leaf area and leaf fresh weight (LFW). T1 presented the best results with increases of 1.4 fold in LFW compared to plants supplemented with QF. T2 was the most effective treatment for radish with the best results of root fresh weight and root diameter. Although T4 had the highest nitrogen content, it did not present the best results in growth performance for lettuce or radish. The presence of higher proportions of SD in composts (25% for lettuce and 50% for radish) improved the physical characteristics of the soil and proved to be a more balanced compost.

[Characterization of Phosphorus Forms in Organic Composts and Their Effects on Leaf Phosphorus Content of Castanea mollissima in Chinese Chestnut Producing Area].

Characterization of the forms of phosphorus (P) in four organic composts including compost of hulls and leaves of Castanea mollissima, edible fungi residues, corn stalks and chicken manure (BYZ), compost of edible fungi residues and chicken manure(ZF), composts of hulls and leaves of C. mollissima, edible fungi residues and chicken manure (BZ1 and BZ2) in Chinese chestnut producing area was conducted by sequential P fractionation developed by Dou et al. Field trial was conducted to study the effects of compost application on leaf phosphorus content of Castanea mollissima. The results showed that total phosphorus content(TP) of organic composts ranked as follows:BZ1(10.61 g·kg-1) > ZF(9.03 g·kg-1) > BYZ(8.56 g·kg-1) > BZ2(7.68 g·kg-1), and the inorganic phosphorus(Pi) accounted for 62.88%-73.62% of the total phosphorus in the organic composts. The content and proportion of HCl-P in the total fractionated phosphorus(Prt) was the highest among P forms in ZF, while that of H2O-P was the highest in BYZ, BZ1 and BZ2. The content of NaOH-P was very low in all the composts. Active H2O-Por NaHCO3-P had the highest inorganic phosphorus proportion(89.17%-96.00%) of all the P forms. The major Piforms in BZ2 were H2O- and HCl-extractable P fractions, while H2O-Pi, HCl-Pi and NaHCO3-Pi were major Pi forms in BYZ, BZ1 and ZF. Residual-P was the predominant organic phosphorus form, and BZ2 showed the highest Residual-P proportion of the total fractionated phosphorus(Prt) among all the composts. Leaf phosphorus contents per unit area of Castanea mollissima by field trial on the added phosphorus-equivalent basis were expressed as:BZ2>BZ1>BYZ>ZF>CK. Increment of leaf phosphorus content per unit area in Julyand per month on average showed positive relationship with the content and proportion of H2O-Pi in the total fractionated phosphorus of composts, which presumably played a key role in leaf phosphorus absorption of C. mollissima measured in the year of deep concentrated fertilization. The results suggested that composts of hulls and leaves of C. mollissima, edible fungi residues and chicken manure (BZ2) was a good choice in given area for aerobic composting raw material system in which organic wastes from Chinese chestnut industry accounted for 80% (hulls and leaves of Castanea mollissima and edible fungi residues accounted for 60% and 20% respectively), which had a high proportion of H2O-Pi and organic Residual-P pool and led to the highest leaf phosphorus content of C. mollissima.

Rendimento de feijão e alterações no pH e na matéria orgânica do solo em função de doses de composto de resíduo de algodão / Yield of bean plant and changes in pH and soil organic matter as a function of doses of compost cotton waste

O objetivo do presente trabalho foi avaliar o rendimento de feijão e as alterações no pH e na matéria orgânica do solo após a aplicação do composto de resíduo de algodão. Para tanto, instalou-se o experimento em condições de campo, em um Argissolo Vermelho-Amarelo. O delineamento experimental foi em blocos ao acaso com cinco tratamentos constituídos por doses (0, 20, 40, 60, 80t ha-1) de resíduo de algodão compostado oriundo da indústria têxtil, com cinco repetições. Verificou-se que a aplicação do resíduo de algodão compostado promoveu melhoria nas características produtivas do feijoeiro submetido ao manejo orgânico e elevou os valores de pH e matéria orgânica do solo. Desse modo, o composto utilizado mostrou-se como uma alternativa para a adubação da cultura.

The objective of this research was to evaluate the yield of bean plants and changes in pH and soil organic matter after compost cotton waste application. An experiment was carried out in an Acrisol. The experimental design was of randomized blocks with five levels of cotton waste compost (0, 20, 40, 60, 80t ha-1) from the textile factory, in five replications. The application of the cotton waste compost promoted increase in the growth and productive characteristics in bean crop, and increased the pH values and soil organic matter. Thus, the compost showed as an alternative for fertilization of the culture.