Perspectives and understanding on the occurrence, toxicity and abatement technologies of disinfection by-products in drinking water.

Disinfection by-products (DBPs) are one of the significant emerging contaminants that have caught the attention of researchers worldwide due to their pervasiveness. Their presence in drinking water, even in shallow concentrations (in levels of parts per billion), poses considerable health risks. Therefore, it is crucial to understand their kinetics to understand better their formation and persistence in the water supply systems. This manuscript demonstrates different aspects of research carried out on DBPs in the past. A systematic approach was adopted for the bibliographical research that started with choosing appropriate keywords and identifying the most relevant manuscripts through the screening process. This follows a quantitative assessment of the extracted literature sample, which included the most productive and influential journal sources, the most widely used keywords, the most influential authors active in the research domain, the most cited articles, and the countries most actively engaged in the research field. Critical observations on the literature sample led to the qualitative assessment, wherein the past and current research trends were observed and reported. Finally, we identified the essential gaps in the available literature, which further led to recommending the course ahead in the research domain. This study will prove fruitful for young and established researchers who are or wish to work in this emerging field of research.

Thermal pretreatment of Lantana camara for improved biogas production: Process parameter studies for energy evaluation.

The rigid lignocellulosic structure of Lantana camara impedes the hydrolysis phase and reduces the biogas production during anaerobic digestion of Lantana camara. Hence, the current study focuses on the impact of various heating pretreatment techniques, viz., hot air oven (HAO), autoclave (ATC), hot water bath (HWB), and microwave (MCW) on L. camara to speed up hydrolysis and boost up biogas production. ATC pretreatment of L. camara was witnessed to be most efficient compared to HAO, MCW, and HWB pretreatment. ATC pretreatment enhanced the solubilization (45.44%), and an increment in volatile fatty acids (VFA) was observed (56.75%) at 110 °C for 80 min when correlated to the untreated (control). Cumulative methane production following ATC pretreatment had risen to 3656 mL in 5 weeks from 2895 mL in 7 weeks. Thermal pretreatment of Lantana camara broke down the rigid lignocellulosic structure, accelerating the hydrolysis stage and improving biogas production simultaneously. To the best of our knowledge, this is the first thermal pretreatment study conducted on Lantana camara for biogas production.

Ecological and health risk assessment associated with translocation of heavy metals in Lycopersicum esculentum from farmland soil treated with different composts.

To meet the United Nations' Sustainable Development Goals, agricultural soil which is a non-renewable natural resource must be carefully managed. Heavy metals present in agricultural soil may imperil food security and instigate extreme risks to human health. Organic wastes have been long known for valuable amendments to soil thereby, improving overall soil health. In the present study, Echhornia crassipes, Hydrilla verticillata, and vegetable waste, was utilized to prepare compost amendments. Lycopersicum esculentum was used to metal uptake from compost amended soils. 5%, 10%, 15%, 25%, and 35% compost: soil (w/w) were studied to understand metal translocation in plants. Potential Ecological risk indices showed that while the degree of risk was medium for the natural soil, it reduced to slight for the soil amended with WHC and VWC for all compositions. The non-carcinogenic risks associated with the human health reduced on application of the composts, however, they still remained substantial for Fe, As, and Pb for WHC, HVC, and VWC composts at higher application ratios, especially among children. On the other hand, the carcinogenic health index values which were calculated to estimate the risk associated with ingestion of L. esculentum, showed a decrease in risk for all the metals studied, upon soil amendment. Soil amended with HVC compost showed an increase in carcinogenic risk for As, Pb, and Cr. Finally, we conclude that biological soil remediation is economical and a sustainable land management strategy that may lead to green and clean remediation solutions for metal contaminated soil.

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.

Enhancement of soil physico-chemical properties post compost application: Optimization using Response Surface Methodology comprehending Central Composite Design.

The application of compost has been recognized as one of the most promising approaches for preserving soil quality and crop production. The present study exhaustively investigates the impact of Water Hyacinth Compost (WHC), Hydrilla verticillata Compost (HVC) and Vegetable Waste Compost (VWC) on soil nutrient quality and engineering properties [Bulk Density (BD), water retention and specific gravity]. For the study, six different proportions constituting 5, 10, 15, 25, 35 and 45% of the composts by weight of the soil were taken. The soil compost mixtures were evaluated at different periods (0, 15, 30, 45, 60 and 120 days) for various nutrients [Na, Mg, P, K, Ca, Total Organic Carbon (TOC), Total Kjeldahl Nitrogen (TKN)], BD, water retention capacity, change in specific gravity and Cation Exchange Capacity (CEC) values. It was observed that when the percentage of compost was increased to 15-45%, it resulted in enhanced nutrient value of the soil. Also, for WHC, HVC and VWC 60 days was sufficient to improve the soil quality to its maximum extend. Based on the optimized physico-chemical properties generated from the Response Surface Methodology (RSM) model, it was found that compared to WHC and HVC, the VWC performed better results viz., generating low BD (0.87 g/cm3), high water retention capacity (45.63%) and degree of saturation (77.49%) of the soil. While WHC, HVC and VWC can be used to improve soil nutrient content and overall physico-chemical parameters in long terms, VWC could be more efficient and beneficial to degraded soil for restoring soil health.

Bio-inherent attributes of water hyacinth procured from contaminated water body-effect of its compost on seed germination and radicle growth.

Compost is generally used for soil conditioning, growing plants and remediation of pollution. It is imperative to evaluate compost standard and toxicity test is a salient parameter for determining compost quality. Seed germination test is an essential method to discern the phytotoxicity of compost. Ecotoxicity of water hyacinth compost was inspected for the denouement of the compost quintessence and its concentration on seed germination indices. The aim of this paper was to assess seed emergence rate index, germination velocity coefficient and rate of germination of L. esculentum and B. oleracea at discrete concentrations of water hyacinth compost. The highest germination percentage achieved was 95% (L. esculentum) at 100 g/L and 100% (B. oleracea) at 32 g/L of the compost extract. The probability of inadvertent ceasing of germination was found to be < 0.0001 for either of the test species. Consequently, the water hyacinth compost aid plant growth and is recommended for substantially ameliorating languishing ecological idiosyncrasy.

Drum composting of municipal solid waste.

The high initial C/N ratio (> 30) found in Indian municipal solid waste (MSW) leads to more time required for composting (> 3 months), with poor-quality compost production. Therefore, the effects of MSW amended with cattle manure (trial 1) and tree leaves (trial 2) were compared with unamended MSW (control) in a rotary drum composter. The initial C/N ratios of trial 1 and trial 2 were kept at 22, as compared to 32 for the MSW control sample. It was observed that trial 1 produced high-quality and stable compost within 20 days. It showed higher final total nitrogen (2.2%), final total phosphorus (3.2 g/kg) and low electrical conductivity (2.7 dS/m). At the end of 20 days, higher degradation caused lower final oxygen uptake rate (OUR) (1.8 mg/g volatile solids (VS)/day), final CO2 evolution (1.0 mg/g VS/day) and final C/N ratio (7.8). Trial 2 produced good-quality and stable compost resulting in 1.9% of total nitrogen, 2.7% of total phosphorus and low OUR (2.0 mg/g VS/day), CO2 evolution (1.5 mg/g VS/day) and C/N ratio (10.1) after 20 days ofcomposting. However, the control sample with an initial C/N ratio of 32 showed higher OUR (3.6 mg/g VS/day) and CO2 evolution (2.6 mg/g VS/day) comprising a lower concentration of total nitrogen (1.6%) and total phosphorus (2.3 g/kg), which indicated an unstable and low-quality product as compared to trials 1 and 2. Therefore, results showed that the characteristics of MSW amended with cattle manure and tree leaves significantly influence the compost quality and process dynamics in a rotary drum composter.

Management of invasive weed Parthenium hysterophorus through vermicomposting using a polyculture of Eisenia fetida and Eudrilus eugeniae.

Parthenium hysterophorus is considered one of the most noxious terrestrial weeds which needs to be efficiently managed to sustain the environment and vermicomposting are a promising eco-friendly management technique. In the current study, vermicomposting of P. hysterophorus was carried out using a polyculture of two epigeic earthworm species, i.e., Eisenia fetida and Eudrilus eugeniae employed in five different vermireactors referred as Rp1, Rp2, Rp3, Rp4, and Rp5 with five mixing ratios 3:7, 4:6, 5:5, 6:4, and 7:3 respectively of P. hysterophorus to cow dung as a blending material. The nutrients in the final vermicompost were determined by analyzing different physico-chemical parameters and the efficiency evaluated by the growth rate of earthworms. After vermicomposting, TKN, TP, and K contents increased with the highest percentage change of 74.74%, 91%, and 47.2% respectively, compared to initial values. Reduction in C/N ratio was observed in all the vermireactors with the lowest C/N ratio of 9.76. EC increased for all the vermireactors during the process and reached in the range of 3.7-3.85 ds/m at the end of the process. The highest percentage gain in biomass of earthworms was 46.25% in Rp2. Vermicomposting of P. hysterophorus is possible for the management of this invasive weed through polyculture of the earthworms E. fetida and E. eugeniae to obtain a value-added organic fertilizer, i.e., vermicompost by a sustainable process.

Management of lignocellulosic green waste Saccharum spontaenum through vermicomposting with cow dung.

Saccharum spontaenum is considered as an invasive terrestrial weed spread across the world and its management possess big challenge to the research community. The current study illustrates the potential of vermicomposting for the management of lignocellulosic terrestrial weed Saccharum spontaenum under green waste management. The vermicompost experiments were done in five different mixing ratio of Saccharum spontaenum amended with cow dung 3:7, 4:6, 5:5, 6:4, 7:3 in vermireactors referred as Ref1, Ref2, Ref3, Ref4, Ref5 respectively. The vermicomposting was carried out for total 45 days with one time feeding of the earthworms. The study indicates a mature vermicompost can be obtained with enhanced nutrients from proper mixing ratio. The different physicochemical parameters were observed to be varied among the reactors and between vermicomposting time significantly. The final C/N ratio was within 10-16 with highest decrease in Ref1. Earthworm growth was observed to be highest in Ref2 with percentage change of net biomass of earthworms with 34.25%. The highest TOC loss was observed to be 31.4% change in Ref2 and maximum TKN was 2.95% in the final vermicompost of Ref3. Even though the mixing ratio of Ref1 and Ref2 was found to be ideal for the degradation of Saccharum spontaenum, the other reactors also produced acceptable quality end product. The study further reveals that the earthworm species Eisenia fetida was highly suitable for the biodegradation of this lignocellulosic weed material.

Bioconversion of Lantana camara by vermicomposting with two different earthworm species in monoculture.

The experiments were performed in bamboo containers with five different reactors (Ref1/Ree1, Ref2/Ree2, Ref3/Ree3, Ref4/Ree4, Ref5/Ree5) of varying substrate and cow dung ratio for earthworms i.e. Eisenia fetida and Eudrilus euginae. Physicochemical properties of the vermicompost produced by each earthworm were evaluated and the performance of both the earthworms was compared. pH was within 7.1-7.5 for all the reactors. The highest Total Kjedahl Nitrogen (TKN) value was found for Ref4 with 2.78% whereas it was lowest for Ree1 (2.48%). The highest 32.46% change in Total Organic Carbon (TOC) was observed for Ref3. At the end of the process C/N ratio was found within 11-14 for both the earthworms. In terms of growth both the earthworms performed well whereas highest net biomass gain for Eisenia fetida in Ref3 with 37.5%. Vermicomposting is found to be beneficial for the management of Lantana camara. Eisenia fetida performed better as compared to Eudrilus euginae.

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.

Anaerobic biodegradability test for Lantana camara to optimize the appropriate food to microorganism (F/M) ratio.

Invasion of Lantana camara all over the world and its management is a global problematic issue. Its rapid growth and competition with natural resources such as space, water, and nutrients of other plants, reasons for the demand to manage this noxious weed. This study was done to optimize the ideal food to microorganism (F/M) ratio. Different food to microorganism (F/M) ratios of 1, 1.5, 2 and 2.5 were studied along with one control where only cow dung was kept. Highest methane production was obtained from the F/M ratio of 1.5 (195.5 ± 8 mL CH4/g VS) and cumulative methane production from it was 4801.5 mL followed by ratios 2 and 2.5 respectively. In control, methane production was relatively low as compared to all the F/M ratios (2151.5 ± 8 mL). 20 L capacity batch reactor was performed with a working volume of 15.5 L where substrate and cow dung were fed according to the best ratio found during biochemical methane potential trial (BMP). Maximum methane yield was observed on the 19th day (2650 ± 18 ml CH4/g VS). Maximum volatile solids (VS) reduction was observed in the F/M ratio 1.5 (49.63%) followed by 2 and 2.5 respectively. The maximum amount of volatile fatty acid (VFA) was produced in F/M ratio 1.5 (715 ± 10) and 2 (715 ± 15) followed by ratios 2.5 and 1 respectively. Maximum soluble chemical oxygen demand (sCOD) was found in F/M ratio 1.5 (8000 mg/L). Morphological changes were captured in FESEM and XRD.

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.

Vermitechnology for sewage sludge recycling.

The present paper is aimed at safe reuse and recycling of sewage sludge (SS) and production of good quality compost using vermicomposting. Three different earthworm species Eiseniafetida (E. fetida), Eudrilus eugeniae (E. eugeniae), Perionyx excavatus (P. excavatus) in individual and combinations were utilized to compare the suitability of worm species for composting of sewage sludge as well as the quality of the end product. The sewage sludge without blending can be directly converted into good quality fertilizer (vermicompost). Vermicomposting resulted in reduction in C/N ratio 25.6 to 6-9, TOC (25%) but increase in electrical conductivity (EC) (47-51%), total nitrogen (TN) (2.4-2.8 times), potassium (45-71%), calcium (49-62%), sodium (62-82%) and total phosphorous (TP) (1.5-1.8 times), which indicated that sewage sludge can be recycled as a good quality fertilizer. The present study also inferred that the application of sewage sludge in the agricultural fields after vermicomposting would not have any adverse effect as the heavy metals (Cu, Mn, Pb and Zn) are now within the permissible limits.

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

Primary paper mill sludge (PPMS) is the major waste expelled from the pulp and paper industries contributing soil and water pollution through the recalcitrant organic and inorganic constituents. These pollutants can, however, be transformed into a high-value soil ameliorating material with nominal investment and time. Current study therefore evaluated the potential of rotary drum composting PPMS for 20 days to delineate an environmentally sustainable option. Five trials with proportions of PPMS, cow dung and saw dust: Trial 1 (10:0:0), Trial 2 (8:1:1), Trial 3 (7:2:1), Trial 4 (6:3:1) and Trial 5 (5:4:1) were performed for evaluation of degrading and nutritive ability along with the fate of pollutants for total mass of 150 kg. Trial 4 exhibited highest metabolic activity contributing higher temperature evolution and longer thermophilic phase (10 days) owing to optimum addition of innoculum and nitrogen through the cattle manure. Moreover, degradation of 16.8% organic matter was also best achieved in Trial 4 following up first-order kinetics. Furthermore, BOD, COD and C/N ratio also explains degradation to be maximum in trial 4 (6:3:1) with reduction of 59.3%, 60.1% and C/N ratio from 55.1 to 18 respectively, proving to be the essential determining factors. Phosphorus availability increased by around 67% in trial 4. PPMS can be thus transformed into a potential valued added product and safe for subsequent land application.

Vermicomposting and anaerobic digestion - viable alternative options for terrestrial weed management - A review.

The management of terrestrial weed is of great concern for the scientific community as these weeds cause adverse effect in different ecosystems like forest, agriculture and urban. The widespread of these weeds by their adaptive capability and morphological advancement is difficult to control. Parthenium hysterophorous, Lantana camara, Saccharum spontaneum, Ageratum conyzoides are the weeds that spread all over the world. There are various management practices employed for the control of this weeds. But all of these practices have some drawbacks those are neither environment friendly nor economical. In this paper a review has been done to evaluate various alternative management practices for these terrestrial weeds and to analyze their feasibility. Vermicomposting and anaerobic digestion can be viable alternative option which is cost effective as well. There are few studies regarding vermicomposting and anaerobic digestions of terrestrial weeds are done.

Bioconversion of filter mud using vermicomposting employing two exotic and one local earthworm species.

Three different earthworm species Eisenia fetida, Eudrilus eugeniae and Perionyx excavatus in individual (Monocultures) and combinations (Polycultures) were utilized to compare the suitability of worm species for vermicomposting of filter mud as well as the quality of the end product. The filter mud blended with saw dust can be directly converted into good quality fertilizer (vermicompost). Eight different reactors including three monocultures and four polycultures of E. fetida, E. eugeniae and P. excavatus and one control were used for the experiment. Vermicomposting resulted in significant reduction in C/N ratio, pH, total organic matter (TOC) but increase in electrical conductivity (EC), total nitrogen (TN), total phosphorus (TP) and macronutrients (K, Ca and Na). Oxygen uptake rate (OUR) dropped up to 1.64-1.95 mg/g (volatile solids) VS/day for monoculture reactors and 1.45-1.78 mg/g VS/day for polycultures reactors, respectively, after 45 days of vermicomposting. Cocoon production and the earthworm biomass increased as vermicomposting progressed. On an overall the mono as well as polyculture reactors produced high quality stable compost free from pathogens and no specific differentiation could be inferred between the reactors.

Rotary drum composting of vegetable waste and tree leaves.

High rate composting studies on institutional waste, i.e. vegetable wastes, tree leaves, etc., were conducted on a demonstration-scale (3.5 m(3)) rotary drum composter by evaluating changes in some physico-chemical and biological parameters. During composting, higher temperature (60-70 degrees C) at inlet zone and (50-60 degrees C) at middle zone were achieved which resulted in high degradation in the drum. As a result, all parameters including TOC, C/N ratio, CO(2) evolution and coliforms were decreased significantly within few days of composting. Within a week period, quality compost with total nitrogen (2.6%) and final total phosphorus (6 g/kg) was achieved; but relatively higher final values of fecal coliforms and CO(2) evolution, suggested further maturation. Thus, two conventional composting methods namely windrow (M1) and vermicomposting (M2) tried for maturation of primary stabilized compost. By examining these methods, it was suggested that M2 was found suitable in delivering fine grained, better quality matured compost within 20 days of maturation period.