Impact of composting factors on the biodegradation of lignin in Eichhornia crassipes (water hyacinth): A response surface methodological (RSM) investigation

Effect of Charcoal on the Quality of Vermicompost Produced With Water Hyacinth and Cow Manure

The significance of water hyacinth (Pontederia crassipes (C. Mart.) Solms (Pontederiaceae) vermicomposting lies in its ability to effectively manage its invasiveness while also improving soil fertility and supporting sustainable agricultural practices. This study evaluates the effects of charcoal addition on the composting followed by the vermicomposting of water hyacinth (WH) and cow manure, focusing on the growth, reproduction, and survival of Eisenia fetida earthworms and the quality of the resulting vermicompost. The treatments included WH and cow manure (2:1) with 7.5% charcoal (T1), 5% charcoal (T2), and without charcoal (T3). Composting (30 days) followed by vermicomposting (60 days) was conducted in a controlled greenhouse environment. Samples were collected biweekly to analyze temperature, moisture, pH, electrical conductivity, total nitrogen, total available phosphorous, and total potassium contents, vermicompost yield, and earthworm growth parameters throughout the process. Results showed that T1 and T2 significantly improved earthworm weight (8.23-16.0%), number of earthworms (65.0-69.0%), cocoon production (37.0-49.0%), and hatchling count (49.0-77.6%), compared to T3 (control). Also, T1 and T2 increased pH (4.30-5.75%), total nitrogen (53.6-62.5%), total available phosphorus (61.6-117%), and total potassium (47.5-71.3%) and reduced electrical conductivity (9.91%), total organic carbon (17.9-42.1%), carbon: nitrogen ratio (46.5-64.4%), and vermicompost mass (22.0-28.3%) at the end of the vermicomposting period, compared to T3. Moreover, T1 and T2 exhibited significantly higher lettuce seed germination (92.4-93.5%), germination index (76.2-80.4%), shoot elongation (46.0-92.5%), and root elongation (9.00-15.0%), compared to T3. However, in most of the results, there was no significant difference between T1 and T2. This finding suggests that the use of T2 (5.00%) charcoal addition enhances vermicompost quality to optimal maturity and stability.

Mathematical and computational modeling for organic and insect frass fertilizer production: A systematic review

Organic fertilizers have been identified as a sustainable agricultural practice that can enhance productivity and reduce environmental impact. Recently, the European Union defined and accepted insect frass as an innovative and emerging organic fertilizer. In the wider domain of organic fertilizers, mathematical and computational models have been developed to optimize their production and application conditions. However, with the advancement in policies and regulations, modelling has shifted towards efficiencies in the deployment of these technologies. Therefore, this paper reviews and critically analyzes the recent developments in the mathematical and computation modeling that have promoted various organic fertilizer products including insect frass. We reviewed a total of 35 studies and discussed the methodologies, benefits, and challenges associated with the use of these models. The results show that mathematical and computational modeling can improve the efficiency and effectiveness of organic fertilizer production, leading to improved agricultural productivity and reduced environmental impact. Mathematical models such as simulation, regression, dynamics, and kinetics have been applied while computational data driven machine learning models such as random forest, support vector machines, gradient boosting, and artificial neural networks have also been applied as well. These models have been used in quantifying nutrients concentration/release, effects of nutrients in agro-production, and fertilizer treatment. This paper also discusses prospects for the use of these models, including the development of more comprehensive and accurate models and integration with emerging technologies such as Internet of Things.

Screening of cellulose-degrading bacteria and optimization of cellulase production from Bacillus cereus A49 through response surface methodology

Cellulose-degrading microorganisms hold immense significance in utilizing cellulose resources efficiently. The screening of natural cellulase bacteria and the optimization of fermentation conditions are the hot spots of research. This study meticulously screened cellulose-degrading bacteria from mixed soil samples adopting a multi-step approach, encompassing preliminary culture medium screening, Congo red medium-based re-screening, and quantification of cellulase activity across various strains. Particularly, three robust cellulase-producing strains were identified: A24 (MT740356.1 Brevibacillus borstelensis), A49 (MT740358.1 Bacillus cereus), and A61 (MT740357.1 Paenibacillus sp.). For subsequent cultivation experiments, the growth curves of the three obtained isolates were monitored diligently. Additionally, optimal CMCase production conditions were determined, keeping CMCase activity as a key metric, through a series of single-factor experiments: agitation speed, cultivation temperature, unit medium concentration, and inoculum volume. Maximum CMCase production was observed at 150 rpm/37 °C, doubling the unit medium addition, and a 5 mL inoculation volume. Further optimization was conducted using the selected isolate A49 employing response surface methodology. The software model recommended a 2.21fold unit medium addition, 36.11 °C temperature, and 4.91 mL inoculant volume for optimal CMCase production. Consequently, three parallel experiments were conducted based on predicted conditions consistently yielding an average CMCase production activity of 15.63 U/mL, closely aligning with the predicted value of 16.41 U/mL. These findings validated the reliability of the model and demonstrated the effectiveness of optimized CMCase production conditions for isolate A49.

Role of different natural materials in reducing nitrogen loss during industrial sludge composting: Modelling and optimization

In this study, the effects of pumice, expanded perlite, and expanded vermiculite on nitrogen loss were examined for industrial sludge composting using the Box-Behnken experimental design. The independent factors and their levels were selected as amendment type, amendment ratio, and aeration rate, and codded as x₁, x₂, and x₃ at 3 levels (low, center, and high). The statistical significance of independent variables and their interactions were determined at 95% confidence limits by Analysis of Variance. The quadratic polynomial regression equation produced to predict the responses was solved and the optimum values of the variables were predicted by analyzing the three-dimensional response surfaces plots. The optimum conditions for minimum nitrogen loss by the regression model were as pumice of amendment type, 40% of amendment ratio, and 6 L/min of aeration rate. In this study, it was observed that time-consuming and laborious laboratory work can be minimized with the Box-Behnken experimental design.

Biostimulation of Petroleum-Contaminated Soil Using Organic and Inorganic Amendments

The most common approaches for the in-situ bioremediation of contaminated sites worldwide are bioaugmentation and biostimulation. Biostimulation has often proved more effective for chronically contaminated sites. This study examined the effectiveness of optimized water hyacinth compost in comparison with other organic and inorganic amendments for the remediation of crude oil-polluted soils. Water hyacinth was found to be rich in nutrients necessary to stimulate microbial growth and activity. An organic geochemical analysis revealed that all amendments in this study increased total petroleum hydrocarbon (TPH) biodegradation by ≥75% within 56 days, with the greatest biodegradation (93%) occurring in sterilized soil inoculated with optimized water hyacinth compost. This was followed by polluted soil amended with a combination of spent mushroom and water hyacinth composts (SMC + WH), which recorded a TPH biodegradation of 89%. Soil amendment using the inorganic fertilizer NPK (20:10:10) resulted in 86% TPH biodegradation. On the other hand, control samples (natural attenuation) recorded only 4% degradation. A molecular analysis of residual polycyclic aromatic hydrocarbons (PAHs) showed that the 16 PAHs designated by the US EPA as priority pollutants were either completely or highly degraded in the combined treatment (SMC + WH), indicating the potential of this amendment for the environmental remediation of soils contaminated with recalcitrant organic pollutants.