Evaluation of biodegradation feasibility through rotary drum composting recalcitrant primary paper mill sludge

Integrated enzyme hydrolysis assisted cellulose nanofibril (CNF) fabrication: A sustainable approach to paper mill sludge (PMS) management

The landfilling of paper mill sludge (PMS) has been restricted or even banned in many countries due to the raised concern about greenhouse gas (GHG) emissions and contamination of the soil and water, calling for a sustainable PMS management approach. The potential valorization of PMS to nanomaterials combined with traditional biorefinery was examined in this work. Three types of PMS-derived cellulose nanofibrils (CNFs) were prepared and evaluated: enzymatically assisted CNF (AU: with in-house produced enzyme and CT: with commercial enzyme), mechanically pretreated CNF (BT), and chemically pretreated CNF by TEMPO oxidation (TEMPO). It was found that enzyme-assisted mechanical fibrillation-derived CNFs had a comparable average diameter (27.9 nm for AU and 22.7 nm for CT) with that produced from mechanical pretreatment (26.5 nm for BT) and TEMPO oxidation pretreatment (20.0 nm for TEMPO), and they showed the best drainage properties among the three types of CNF. The CNFs resulting from enzymatic pretreatment reduced 15% of energy consumption compared to the mechanical method and had better thermostability than TEMPO oxidation method. In addition, the on-site produced enzyme showed similar performance to the commercial enzymes towards the CNF properties. These findings provide new insights into a promising integrated strategy in engineering CNF from PMS with on-site enzyme production as a novel and sustainable approach for PMS management and valorization.

Bioconversion of Eichhornia crassipes into vermicompost on a large scale through improving operational aspects of in-vessel biodegradation process: Microbial dynamics

Eichhornia crassipes is a common, abundant aquatic weed biomass found globally. The present study examined optimum biodegradation procedures through batch studies (550 L rotating drum composter) and the resulting best combination on a large scale (5000 L rotary drum composter). The pilot scale rotary drum reactor was commenced with cow manure and then treated for 3 months with 250 kg/day of homogenously mixed E. crassipes and dry leaves. The rotary drum's inlet and outlet temperatures were 60 °C and 39 °C, respectively, suggesting thermophilic conditions with a 7-day waste retention duration. Eisenia fetida was used for vermicomposting the outlet material for 20 days, raising the nitrogen content to 3.2%. Bacterial diversity (16S-rRNA) sequencing revealed that Proteobacteria and Euryarchaeota are the most predominant. After 27 days, the volume dropped by 71%, and the product was stable and soil-safe. Large-scale optimised biodegradation may be a better way to handle aquatic weed biomass.

Impacts of utilizing swine lagoon sludge as a composting ingredient

Lagoon sludge, a byproduct of swine operations in the Southeast United States, poses a management challenge due to its high mineral and metal content. Composting is a low-cost, scalable technology for manure management. However, limited information is available on composting swine lagoon sludge in terms of recipes, greenhouse gas emissions and end-product quality. Moreover, due to its high Zn and Cu content, high inclusion of sludge in composting recipes can potentially inhibit the process. To address these knowledge gaps, in-vessel aerated composting (0.4 m3each) was carried out to evaluate impacts of sludge inclusion, at 10% (Low Sludge, LS-Recipe) and 20% (High sludge, HS-Recipe) wet mass-basis, on composting process and end-product quality. Comparable maximum temperatures (74 ± 2.7 °C, 74.9 ± 2.9 °C), and organic matter loss were observed in both recipes. Similarly, sludge inclusion ratio had no significant impact on cumulative GHG emissions. The global warming potential (20-year GWP) for swine lagoon sludge composting using LS and HS recipes was observed to be 241.9 (±13.3) and 229.9 (±8.7) kg CO2-e/tDM respectively. Both recipes lost 24-28% of initial carbon (C) and 4-15% of nitrogen (N) respectively. Composting and curing did not change water-extractable (WE) phosphorus (P) concentrations while WE Zn and Cu concentrations decreased by 67-74% and 55-59% respectively in both recipes. End compost was stable (respiration rates <2 mgCO2-C/g OM/day) with germination index >93 for both recipes.

Biodegradation of an intrusive weed Parthenium hysterophorus through in-vessel composting technique: toxicity assessment and spectroscopic study

Parthenium hysterophorus is a toxic terrestrial weed with its erratic behavior brought on by the presence of toxic compounds. A numerous works have been conducted on the complete eradication of this weed, but due to the residuals exists in soil, the weed re-grows. Current study therefore aims at examining the transformation of this weed by an in-vessel composting approach (rotary drum composter) and the evaluation of toxicity characteristics using Vigna radiata and Allium cepa as bioindicators. The nutritional content such as total Kjeldahl nitrogen (TKN), total phosphorus (TP), and total potassium were increased by 38.8, 39.1, and 49.5%, respectively, and the reactor was effective in reducing the biochemical content such as lignin, hemicellulose, and cellulose by 43.5, 50.7, and 57.3%, respectively, in the final compost. The thermophilic degradation phase in the reactor existed up to the 8th day of the composting process, which exhibits the highest degradation phase. Meanwhile, the degradation of phenolic, aliphatic, and lignocellulose was investigated and validated using Fourier transform infrared spectroscopy (FTIR) and powdered X-ray diffraction (PXRD) analysis. Although P. hysterophorus exhibited phytotoxic and cyto-genotoxic effects in plant models at the beginning of the composting process, the toxicity potential appeared to be reduced after 20 days of composting. Therefore, the study's findings proved that the in-vessel composting of P. hysterophorus can produce a nontoxic, nutrient-rich compost product that could be used as a soil conditioner in agricultural farmlands. The insights of the study are not limited to the nutritional, stability, and quality characteristics but also the toxicity characteristics during the composting process.

Thermophilic-mesophilic biodegradation: An optimized dual-stage biodegradation technique for expeditious stabilization of sewage sludge

The present study investigated the stabilization of fresh sewage sludge through a dual-stage biodegradation process; rotary drum composting in series with vermicomposting. After thermophilic exposure in a rotary drum composter, the partially degraded feedstock was separated into S1 without vermiculture, S2 and S3 with Eudrilus eugeniae and Eisenia fetida vermi-monocultures, respectively. The S3-derived vermicompost exhibited an 80% and 88% reduction in CO₂ and ammonium-nitrogen evolution rates, respectively, demonstrating the expedient stabilization of sludge. The robust, more than 85% seed germination index supported S2 and S3 derived vermicompost viability. A significant decrease in heavy metals was evinced with S2 and S3-derived vermicompost; the S1-derived end product exhibited higher Zn, Cr, and Pb levels in the absence of vermicomposting. Furthermore, soil amended with 20% vermicompost from S3 displayed 50% more plant growth than S1. Thus, the optimized thermophilic-mesophilic dual-biodegradation technique stabilizes sewage sludge quickly, has a lot of potential in sludge management facilities around the world, and produces a marketable end product.

Biological treatment of Climbing Hempweed biomass through optimized composting technologies - Toxicity assessment and morphological study of Abelmoschus esculentus

Climbing Hempweed (CH) is one of the top ten most obnoxious weeds on the planet, as well as one of the most destructive weeds. Its disastrous spread on the agricultural field has hampered the production of a wide range of crops. Various management techniques have been used to eradicate the weed, but none have been completely successful. As a result, management through the use of weed biomass will aid in the eradication of the weed as well as the production of a value-added product. To utilize invasive weed CH for the production of rotary drum compost (R1) and rotary drum followed by vermicompost (V1), two composting technologies were used. These technologies are being compared on several physicochemical parameters to determine their efficacy. V1 compost had the highest total Kjeldahl Nitrogen (TKN) (3.01%), potassium (3.45%), and total phosphorus (16.42 g/kg) levels, while R1 compost had 2.58% TKN, 2.8% potassium, and 14.25 g/kg total phosphorus. Subsequently, the increasing trends in mitotic index (%) of R1 and V1 samples imply that the cytotoxic effects of CH were decreased due to composting and vermicomposting processes. Genotoxicity assessment revealed that an aberration percentage of 1.64 was observed in 100% concentration of V1 (after 30 days) and 4.34% in R1(after 20 days). R1 and V1 were used to evaluate the performance of Abelmoschus esculentus where the highest fruit harvest was seen at 25% amended R1 compost and 35% amended V1 compost. The application of 25-35% R1 compost and 35-40% V1 compost was found to be the most beneficial for the development of Abelmoschus esculentus. There was no significant difference in heavy metal (Mn, Fe, Cu, Co, and Zn) content in the fruit of Abelmoschus esculentus post-application of R1 and V1 compost.

Performance assessment of in-vessel composter through heavy metal immobilization and humification of Parthenium hysterophorus

The bioconversion of Parthenium hysterophorus was performed through rotary drum composter and examined the mechanism of humification and heavy metals immobilization in the process. The 20th day compost contains a significant increase in humic substances of 28.7% compared to the initial day mix. The bioavailable fractions of heavy metals have reduced by 30 to 55% in the 20th day compost compared to the initial day mix. The leaching potential of cadmium has been reduced by 69% in the 20th day compost. The immobile fractions (F5) of Cd, Ni and Pb have been increased to 100, 99 and 78% in the 20th day compost. The mitotic index was increased by 1.7 and 51.6% in 25% dosed compost extract compared to the control and P. hysterophorus extract respectively. The transition of heavy metals to immobile fraction indicated the biodegradation capability of P. hysterophorus through rotary drum composting.

The Use of Baikal Psychrophilic Actinobacteria for Synthesis of Biologically Active Natural Products from Sawdust Waste

One of the relevant areas in microbiology and biotechnology is the study of microorganisms that induce the destruction of different materials, buildings, and machines and lead to negative effects. At the same time, the positive ecological effects of degradation can be explained by the detoxication of industrial and agricultural wastes, chemical substances, petroleum products, xenobiotics, pesticides, and other chemical pollutants. Many of these industrial wastes include hard-to-degrade components, such as lignocellulose or plastics. The biosynthesis of natural products based on the transformation of lignocellulosic wastes is of particular interest. One of the world’s unique ecosystems is presented by Lake Baikal. This ecosystem is characterized by the highest level of biodiversity, low temperatures, and a high purity of the water. Here, we studied the ability of several psychrophilic representatives of Baikal Actinobacteria to grow on sawdust wastes and transform them into bioactive natural products. Different strains of both widely spread genus of Actinobacteria and rare genera of Actinobacteria were tested. We used the LC-MS methods to show that Actinobacteria living in sawmill wastes can produce both known and novel natural products with antibiotic activity. We demonstrated that the type of sawmill wastes and their concentration influence the Actinobacteria biosynthetic potential. We have shown for the first time that the use of Baikal psychrophilic microorganisms as a factory for biodegradation is applicable for the transformation of lignocellulosic wastes. Thus, the development of techniques for screening novel natural products leads to an elaboration on the active ingredients for novel drugs.

Performance evaluation of a novel two-stage biodegradation technique through management of toxic lignocellulosic terrestrial weeds

The present study investigates the biodegradation of two potentially toxic terrestrial weeds Parthenium hysterophorus and Lantana camara, implementing a novel two-stage biodegradation technique; Rotary drum composting followed by vermicomposting (RV). The RV approach was refined for a 7-day thermophilic degradation in an in-vessel rotary drum composter, followed by a 20-day mesophilic degradation utilizing Eisenia fetida and Eudrilus eugeniae vermi-monocultures. However, rotary drum composting (RDC) was performed for both the weeds (for 27 days), facilitating only initial thermophilic degradation to compare the efficacy of the RV technique. Lignocelluloses analysis revealed that cellulose degradation doubled during RV technique, indicating efficient biodegradation in reactors administered with E. fetida vermiculture compared to RDC (19.60 to 42.80% and 26.80 to 66.50% in P. hysterophorus and L. camara feedstocks). Further, these results also correlated with the X-Ray diffractograms of all trials showing the degradation of crystalline cellulose at 2θ: 20-50° for RV. Moreover, to ensure product safety, the analyzed total heavy metals content also unveiled the advantage of RV over RDC as validated by the accumulation of higher concentrations of zinc (45% and 33% in P. hysterophorus and L. camara feedstocks) and lead (55% and 45% in P. hysterophorus and L. camara feedstocks) in reactors with E. fetida. The material's seed germination index increased to 80% in the final product of all trials in the RV technique, indicating the diminishing of the phytotoxic nature. Subsequently, pot studies also indicated that the RV technique was coherent in managing noxious weeds.

A New Resource Recovery Process for Refining Sludge Generated by a Paper Manufacturing Company

A new sludge processing method was developed by the Beta Company, a paper manufacturing company. The new method will shorten the time for transforming sludge into organic fertilizers, which will improve the process of handling the waste generated by a paper manufacturing company. The paper industry is facing the most rigorous regulations for processing wastewater and sludge to date in the history of many industrialized and developing countries. The Beta Company attempted to improve the conventional method implemented in-company for handling sludge generated during the paper manufacturing process, instead of shipping sludge out-of- company for processing by a third party. The current experimental results show positive improvement, indicating the Beta Company is moving one step closer toward environmental sustainability commitments.

Integrated production of optically pure l-lactic acid from paper mill sludge by simultaneous saccharification and co-fermentation (SSCF)

Paper mill sludge (PMS) raises critical environmental issues due to its disposal problem, but its high sugar content and well-dispersed structure make it a great feedstock for biochemical production. The technical feasibility of integrating cellulase enzyme production into lactic acid (LA) fermentation from PMS was investigated in this study. The low ash content of PMS suggests a great potential for cellulase production. The enzyme produced using PMS without any treatment gave an activity of 7.8 FPU/ml, a performance comparable to the commercial enzyme, Cellic CTec 2. The LA yield from PMS with in-house enzyme was 64.7% and 73.7% at the enzyme loading of 10 and 15 FPU/g-glucan, respectively. The LA obtained was optically pure L- isomer with over 99% purity. The optimal condition of LA production by Bacillus coagulans was found to be 50 °C and pH 5.3 (with 50 g/L CaCO₃). The nutrient effect of yeast extract (YE) and corn steep liquor (CSL) was substrate dependent, and CSL could substitute YE as an inexpensive nutrient when using PMS as a substrate.

Evaluation of rotary drum composting for the management of invasive weed Mikania micrantha Kunth and its toxicity assessment

Mikania micrantha Kunth is an abhorrent weed that destroys agricultural output. It contains toxic compounds that are detrimental to the natural ecosystem and have negative impacts on the economic and aesthetic aspects of the environment. This study depicts the treatment and management of this plant by in-vessel composting using a 550 L rotary drum composter. Six different mix proportions of biomass, cow dung, and sawdust were used for the study. Rotary drum (RD2) with 2.71% has the highest Total Kjeldahl Nitrogen (TKN). Total Organic Carbon (TOC) decreased to 19.72% at the end of the 20th day. Final C/N ratio falls between 7 and 14 in all the reactors. The phytotoxicity test of Mikania was evaluated using Vigna radiata and Allium cepa. The findings of the study suggest that Mikania can be efficiently utilised to produce mature and stable compost that might be recommended for field application as the process can reduce toxicity.

Biogenic stabilization and heavy metal immobilization during vermicomposting of vegetable waste with biochar amendment

Vermicomposting is a traditional technology that produces the best quality of compost, but factors such as maturity, presence of heavy metals, etc. need to be tackled prior to agrarian application. The present study investigates the influence of varying biochar dose (2.5, 5, and 10% on a weight basis) on the maturity of compost and heavy metals during vermicomposting of vegetable waste using epigeic earthworm. Biochar amendment notably enhanced the electrical conductivity (up to 2.7 mS/cm), nitrogen content (up to 3.1%), NO₃-N (up to 630 mg/kg) and nutritional value. The heavy metals, oxygen uptake rate (below 0.96 mg/g VS/day) and CO₂ evolution rate (below 1 mg/g VS/day) were attenuated along with degradation of complex organic crystals as observed in powder X-Ray Diffraction (PXRD) spectra. Furthermore, biochar aid in reducing pathogens (below 1.1 × 10³ MPN/g dry weight) as inferred from the Most Probable Number (MPN) results as well as degrading the complex organics into simpler compounds as revealed from the Fourier-transform infrared spectroscopy (FTIR) spectra. The present study inferred that the vegetable waste was biologically stabilized through biochar amendment during vermicomposting process with improved nutritional and physico-chemical properties.

Co-gasification and co-combustion of industrial solid waste mixtures and their implications on environmental emissions, as an alternative management

The primary sludge produced by the wastewater treatment plant of a pulp and paper mill has high physicochemical heterogeneity, which limits the efficiency of thermochemical methodologies for the final disposal of this residue. As a solution, co-pelletization of the Primary Sludge (PS) with two other principal Industrial Solid Residues (ISRs) of the plant, Coal Boiler Ashes (CBA) and Wood Waste chips (WW), was proposed as a way to valorize the PS for energy use, while reducing dewatering costs. The energy potential was evaluated through a series of thermal co-processing tests of disaggregated and pelletized mixtures. Due to their differing fixed-carbon-to-volatile-material ratios, combining the ISRs resulted in a reduction of up to 45% of the mass of the ISR generated, improving the disposal conditions and achieving a minimum thermal power of 5.0 MJ/Nm³ through gasification. Finally, the environmental implications of the thermal co-processing of the wastes were assessed, finding very low impacts due to pollutant emissions, in accordance with the legal environmental regulations in force in Colombia.

Pulp and paper mill effluent management

This is a review of the literature published in 2018 related to the prevention of water pollution by or recovery of beneficial materials from wastewater produced in the pulp and paper industry. This review includes the following main sections: cleaner production, biological treatment, and physico-chemical treatment. PRACTITIONER POINTS: Converting pulp and paper treatment sludges to value-added materials can be efficient cleaner production technique. Modeling and dynamic simulation techniques of biological treatment along with optimization methods can improve the effluent quality out of a paper mill. Hybrid treatment systems can have a synergistic effect on the treatment of pulp and paper effluents.

Public questions spur the discovery of new bacterial species associated with lignin bioconversion of industrial waste

A citizen science project found that the greenhouse camel cricket (Diestrammena asynamora) is common in North American homes. Public response was to wonder 'what good are they anyway?' and ecology and evolution guided the search for potential benefit. We predicted that camel crickets and similar household species would likely host bacteria with the ability to degrade recalcitrant carbon compounds. Lignocellulose is particularly relevant as it is difficult to degrade yet is an important feedstock for pulp and paper, chemical and biofuel industries. We screened gut bacteria of greenhouse camel crickets and another household insect, the hide beetle (Dermestes maculatus) for the ability to grow on and degrade lignocellulose components as well as the lignocellulose-derived industrial waste product black liquor. From three greenhouse camel crickets and three hide beetles, 14 bacterial strains were identified that were capable of growth on lignocellulosic components, including lignin. Cedecea lapagei was selected for further study due to growth on most lignocellulose components. The C. lapagei secretome was identified using LC/MS/MS analysis. This work demonstrates a novel source of lignocellulose-degrading bacteria and introduces an effective workflow to identify bacterial enzymes for transforming industrial waste into value-added products. More generally, our research suggests the value of ecologically guided discovery of novel organisms.