Tanmoy Karak

Municipal Solid Waste Generation, Composition, and Management: The World Scenario

Municipal solid waste (MSW) is the abridgment of the waste generated from domestic, commercial, and construction activities by natural persons that is collected and treated by municipalities. Exponential growth of population and urbanization, and the development of social economy, coupled with the improvement of living standard, have resulted in an increase in the amount of MSW generation throughout the world. On average the developed countries typically generate 521.95–759.2 kg per person per year (kpc) and 109.5–525.6 kpc typically by developing countries. Recent estimates suggest that the MSW generation globally exceeds 2 billion tons per year, which is a potential threat to environmental dilapidation. Therefore, MSW management (MSWM) seems to be one of the key topics for environmental protection in present days and also in the future. The authors have illustrated MSW generation and composition analysis and have provided a comprehensive review of MSWM in different countries throughout the world based on the available literatures. Some of the important aspects of waste management, such as composting, landfilling, and incineration, are illustrated.

Composting of cow dung and crop residues using termite mounds as bulking agent

The present study reports the suitability of termite mounds as a bulking agent for composting with crop residues and cow dung in pit method. Use of 50 kg termite mound with the crop residues (stover of ground nut: 361.65 kg; soybean: 354.59 kg; potato: 357.67 kg and mustard: 373.19 kg) and cow dung (84.90 kg) formed a good quality compost within 70 days of composting having nitrogen, phosphorus and potassium as 20.19, 3.78 and 32.77 g kg(-1) respectively with a bulk density of 0.85 g cm(-3). Other physico-chemical and germination parameters of the compost were within Indian standard, which had been confirmed by the application of multivariate analysis of variance and multivariate contrast analysis. Principal component analysis was applied in order to gain insight into the characteristic variables. Four composting treatments formed two different groups when hierarchical cluster analysis was applied.

Diversity of Catechin in Northeast Indian Tea Cultivars

Tea (Camellia sinensis L.) leaf contains a large amount of catechins (a group of very active flavonoids) which contribute to major quality attributes of black tea. Based on morphological characters tea plants were classified as Assam, China, and Cambod varieties. The present study is an attempt for biochemical fingerprinting of the tea varieties based on catechin composition in green leaf of cultivars grown in Northeast India. Assam variety cultivars contained the highest level of catechins followed by Cambod and China. The average catechin contents were 231 ± 7 mg g−1, 202 ± 5 mg g−1, and 157 ± 4 mg g−1 of dry weight of green leaf for Assam, Cambod, and China cultivars, respectively. Among the individual catechins the variations in epigallocatechin gallate (EGCG) and epigallocatechin (EGC) were the most prominent among the varieties. High EGC content was found to be a characteristic of Assam variety which was further corroborated through multivariate analysis.

Aluminium dynamics from soil to tea plant (Camellia sinensis L.): is it enhanced by municipal solid waste compost application?

Application of municipal solid waste compost (MSWC) in tea (Camellia sinensis L.) cultivation can increase the fertility status of soils and thus enhance the plant growth. The present study attempts at application of MSWC in tea (TV1 and TV23 clones) cultivation to assess the effect of different doses of MSWC on growth and translocation potential of Al on this plant as well as fate of Al in soil, through the calculation of a risk assessment code (RAC). The sequential extraction of Al in MSWC amended soils showed that the fractionation of Al in soil changed after compost application, with an overall increase of the fractions associated to with Fe-Mn oxides, organic and of the residual fraction. The accumulation of Al in different parts ofC. sinensisL., grown on MSWC amended soil effected an overall increased growth of the plant with increasing doses of MSWC. According to RAC, Al falls in medium to high risk, though no adverse effect on plant health was observed. Tea plants were found to adapt well to MSWC amended soils. However, long term field trials are necessary to completely assess the risk of Al accumulation in soils upon MSWC application. Hierarchical cluster analysis was applied aiming to check for the presence of homogenous groups among different treatments. It was found that in both TV1 and TV23, treatments formed two different groups.

Metal accumulation, biochemical response and yield of Indian mustard grown in soil amended with rural roadside pond sediment.

This present study aims to discern the effect of roadside pond sediments on Brassica juncea (L.) Czern. (cv. Rohini) by examining heavy metal uptake by different parts of the plant and its influence on biochemical properties, biomass, yield and oil content in plant. Although the treated soils were clearly contaminated with heavy metals (HMs) after application of pond sediments and chemical fertilizers, but the metal content in mustard leaves and seeds are below the permissible limit of consumable food. HMs accumulation was proportionally lesser in grains than in shoots and roots. All the biochemical characteristics were significantly (p<0.05) responded to the pond sediments application as compared to the control. Increase in photosynthetic pigment was also observed during growing period while pond sediment was used as amendment. This study revealed that Brassica juncea is well adapted to tolerate and accumulate high quantities of HMs due to increased level of antioxidants (cysteine and ascorbic acid) in roots, shoots and leaves. Multivariate techniques like principal component analysis and cluster analysis (CA) were used as classification techniques. On the basis of factor loadings and principal component scores, different parameters were grouped based on their similarity or closeness, separately in leaves, roots and seeds. A very similar grouping was also obtained using CA. However, pond sediment did not thwart the enhancement of mustard yield and oil content. Therefore, pond sediment would be a valuable resource for mustard as an alternative soil amendment for nutrients, but long-term use may require the cessation to restrict HMs contamination in soils.

Struvite for composting of agricultural wastes with termite mound: Utilizing the unutilized

Although, compost is the store house of different plant nutrients, there is a concern for low amount of major nutrients especially nitrogen content in prepared compost. The present study deals with preparation of compost by using agricultural wastes with struvite (MgNH4PO4·6H2O) along with termite mound. Among four composting mixtures, 50kg termite mound and 2.5kg struvite with crop residues (stover of ground nut: 361.65kg; soybean: 354.59kg; potato: 357.67kg and mustard: 373.19kg) and cow dung (84.90kg) formed a good quality compost within 70days of composting having nitrogen, phosphorus and potassium as 21.59, 3.98 and 34.6gkg(-1), respectively. Multivariate analysis of variance revealed significant differences among the composts. The four composts formed two (pit 1, pit 2 and pit 3, pit 4) different groups. Two principal components expressed more than 97% of the total variability. Hierarchical cluster analysis resulted two homogeneous groups of composts.

Chromium in soil and tea (Camellia sinensis L.) infusion: Does soil amendment with municipal solid waste compost make sense?

In this study, two clones (TV1 and TV23) of tea (Camellia sinensis L.) plants were allowed to grow in earthen pots in a greenhouse, treated with municipal solid waste compost (MSWC) to study the effect of MSWC to the fractionation of chromium (Cr) ion, plant biomass production, plant uptake of Cr, fate of Cr in soils through risk assessment code (RAC) and Cr in tea infusion. Increasing rate of MSWC applications increased both total Cr and DTPA-extractable Cr in soil. Fractionation studies have revealed that Cr in soils was mainly associated with the organic and Fe-Mn oxide and the contribution of residual fractions is nearly 87.7-96.1%. The biomass yields of the tea plants were increased with the increase in MSWC, indicating that nutrient uptake of the plants from MSWC was dependent on the root-MSWC interface. High accumulation of Cr in the root of tea plants and its subsequent lower movement towards aerial parts corroborated the hypothesis that the root of the tea plants acts as a buffer. In this experiment the transfer factor was <1, indicating that the tea plants did not have a significant phytoextraction potential. In the application of 10tha-1 MSWC, Cr was found to be in medium risk for both clones whereas the application of 8tha-1 MSWC showed medium risk with respect to the Cr for TV23 clone applying RAC. Therefore, MSWC amendment rate above 8tha-1 increased the total biomass of the tea plants but posed a threat on environmental prospect with respect to Cr. It was also found that only 2.5μgL-1 to 4.8μgL-1 Cr was present in tea infusion when infusion was prepared from tea leaves receiving different doses of MSWC. Furthermore, stepwise regression technique was applied to choose the most significant regression variables to express the variability in leaves, stem, main root and feeder root biomass. The one-way analysis of variance along with the Dunnetts multiple comparison method was used to determine the significant differences between the means of different treatments. On the application of hierarchical cluster analysis, treatments were grouped in two distinct homogeneous groups.

Heavy Metal Accumulation in Soil Amended with Roadside Pond Sediment and Uptake by Winter Wheat (Triticum aestivum L. cv. PBW 343)

The risks of heavy metal accumulation and the dynamics related to roadside pond sediment application in comparison to control of winter wheat (Triticum aestivum L.) were investigated in field experiments. Selective sequential extraction procedures revealed that application of pond sediment in soil increases the labile pools of the studied heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn). Risk assessment codes concluded that Cu and Pb were in the high-risk zone in both pond sediment and soil amended with pond sediment, whereas Zn and Cu were found in the medium-risk zone for control soil. Heavy metal accumulation by wheat straw and grain (39.38, 1.18, 23.73, 0.36, 0.18, and 16.8 mg kg-1 for Zn, Cd, Cu, Cr, Ni, and Pb, respectively, for wheat grain) was significantly increased through application of pond sediment. However, metal accumulation did not thwart the enhancement of wheat yield when pond sediment was applied. Health risk indexes of analyzed heavy metals were found to be within the Indian permissible limit for foodstuffs. Pond sediments help to fortify wheat grain by increasing the concentration of Zn and Cu as a source of micronutrients in the diet. However, a significant increase of Pb in wheat grain through pond sediment could be a health concern for its long-term application. Therefore, pond sediment would be a valuable resource for agriculture as an alternative organic supplement, but long-term use may require the cessation of the excavated sediment as agricultural landfill in order to restrict heavy metal contamination through it.

Major Soil Chemical Properties of the Major Tea-Growing Areas in India

Abstract Major chemical properties of tea-growing soils are of paramount importance for better management in a sustainable fashion. Therefore, this study was carried out to understand the major soil chemical properties of major tea ( Camellia sinensis L.)-growing areas, Dibrugarh and Tinsukia districts, in the state of Assam, India. A total of 991 surface soil samples were collected from 15 large tea estates (TEs) for analysis of their major chemical properties. Soil pH ranged from 3.61 to 6.81. Total organic carbon and total nitrogen ranged from 2.4 to 47.3 and 0.24 to 3.60 g kg −1 , respectively. All soils were sufficiently rich in plant-available potassium (as K 2 O), which ranged from 127.71 to 252.33 mg kg −1 , exceeding the amount prescribed for optimum tea yield of ≥ 100 mg kg −1 . Plant-available sulfur among soil samples widely varied from 4 to 129 mg kg −1 . Results of hierarchical clustering analysis for homogenous grouping of the 15 TEs based on soil chemical properties showed that the 15 TEs could be classified into three distinct groups which consisted of 6, 8 and 1 TEs, respectively. Based on the Kolmogorov-Smirnov (K-S) test, the best fitted theoretical probability distributions were found out for different soil chemical properties. It could be concluded that a balanced fertilizer application would be needed as a part of tea improvement program using soil chemical test.

Influence of pH on Soil Charge Characteristics and Cadmium Sorption in Some Noncontaminated Soils of Indian Subtropics

Concentrations of total dissolved cadmium (Cd) and activity of its free ions in soil solution are suggested to be influenced by soil pH, organic matter (OM) content, cation exchange capacity (CEC), and clay mineralogy. We investigated the sorption of Cd by taking 25-, 50-, and 100-µM Cd solutions in five noncontaminated soils of West Bengal, India, having differing chemical properties with batch sorption experiments. The charge characteristics and point of zero salt effect (PZSE) of all experimental soils were calculated by the potentiometric titration method measuring the adsorption of H+ and OH– on amphoteric surfaces in solutions of varying ionic strength (I). Sorption of Cd was more pronounced at pH levels greater than PZSE for all experimental soils. The CEC, OM content, clay mineralogy, and specific surface area (SSA) also had a great influence on the sorption of Cd from soil solution to soils. The relationships of Cd with those parameters were found to be consistent and the results concluded that Cd sorption in soils is strongly affected by the soil characteristics.