Physicochemical and biological assessment of legacy waste for application as soil conditioner

The study examines the recycling potential of fine fraction obtained from dumpsites for potential application as a soil conditioner. Legacy waste was excavated from Mulund dumpsite located in Mumbai, India, and < 4 mm fraction (fine fraction) was collected and tested for essential compost parameters like pH, electrical conductivity, total organic carbon (TOC), primary nutrients, and heavy metals. Further, the impact of fine fraction on plant growth was studied using phytotoxicity and vegetation test. The results show that except for TOC, fine fraction meets most of the physicochemical characteristics standard prescribed for Indian MSW-based compost. The fine fraction had significant nutrient content, i.e., 0.81% (N), 0.27% (P as P₂O₅), and 0.55% (K as K₂O), compared to local soil and meets the Indian MSW-based compost standards, except for phosphorous. However, the total heavy metals in fine fraction exceeded the standard limits for chromium, copper, nickel, lead, and zinc. The germination index of tomato seeds (Lycopersicon esculentum) for the fine fraction extract was more than that of the control for aged fine fraction (> 5 years old), whereas inhibition was observed for fine fraction less than 3 years old. The vegetation test on Napier grass (Pennisetum purpureum) showed that the fine fraction amended soil had a 53-56% increase in biomass yield compared to soil. Based on the characteristics of fine fraction, different potential applications, such as fertilizer, soil enricher, or substrate for remediation activity, are identified; however, caution will be desired on a case-to-case basis.

A pilot-scale study of the integrated phycoremediation-photolytic ozonation based municipal solid waste leachate treatment process

Municipal solid waste (MSW) leachate is a highly polluted liquid that accumulates in the landfill and contains a high concentration of toxic pollutants which can pollute the surrounding surface water and groundwater as well, if not treated properly. In this study, an integrated approach of phycoremediation with photolytic ozonation was employed for the leachate collected from the MSW dumpsite which has high Chemical Oxygen Demand (COD) and ammonium (NH₄⁺) levels. Photolytic ozonation treatment was employed as a pre-treatment step under operating parameters of pH: 9.0; Ozone dosage: 5 g/h; UV-C: λ = 254 nm; and contact time: 60 min, in which the COD and NH₄⁺ in the leachate was reduced up to 81% and 95%, respectively. The selected algae Chlorella vulgaris (C.vulgaris) was employed in a lab-scale study to optimize the inoculum conditions in the photolytic ozonated leachate (POL). The specific growth rate of C.vulgaris was observed as 0.14/d in the POL at the optimized condition (inoculum size of 25% (T25)) during the study period of 11 days. High-rate algal pond (HRAP) was employed for the pilot-scale study in controlled environmental conditions as in the T25 experimental run for the assessment of POL treatment and biomass production. C.vulgaris reduced the concentration of pollutants COD, NH₄⁺, and heavy metals (Cu, Fe) in the POL up to 93%, 94%, and 71%, respectively, with the dry biomass productivity of 0.727 g/L/d which is 3 times higher than the biomass productivity of C.vulgaris in freshwater conditions. The biochemical composition (carbohydrates, proteins, and lipids) of the harvested biomass has higher lipid production with lipid productivity of 120 mg/L/d which can be used as a feedstock for the production of value-a dded products.

Composting Strategy Instead of Waste-to-Energy in the Urban Context—A Case Study from Ho Chi Minh City, Vietnam

The waste-to-energy programs that have taken place in recent years present a daunting picture in terms of sustainable material management. The incineration of much organic and unorganized waste in metropolitan waste treatment facilities is not meet with sustainable development. The solution to this problem may be to increase urban composting programs in the future, which is a sustainable treatment option but also a serious technical challenge. Our research question is whether composting programs can play a key role in rapidly evolving urban ecosystems in Asia, due to the specificities associated with the waste rates outlined and developmental differences outlined. Instead of the waste-to-energy or waste-to-landfill strategies often used today, can central composting focusing on high organic matter content be a suitable alternative? Using the AHP method (Analytical Hierarchy Process), the following alternatives were examined to clarify the issue: Wastes are commingled and processed at the treatment facilities; Classification of organic and non-organic waste at source for composting; Totally separating waste at source before processing at the treatment facilities. We have found that the use of central composting (separation of organic and non-organic waste at source) strategies to support circular development is one of the most innovative development strategies in the fast-growing cities of Asia, in line with E.U. targets.

Qualitative assessment of compost engendered from municipal solid waste and green waste by indexing method

The present study aims at quantification of the quality of three varieties of composts made from municipal solid waste, green waste and combined waste by critically evaluating their physicochemical attributes, effect on soil fertility and metal pollution risk. Each waste type was treated with effective micro-organisms to compare the compost quality using Quality Control Indices. The effect of microbial consortia on the wastes was prominent resulting in decreased pH levels and increased electrical conductivity. C/N ratio ranged between 14-24 for waste composts without microbial treatment, and 8-11 for microbial treated wastes. The fertility parameter was observed to be more in microbial treated waste composts. Also, heavy metals concentration in waste compost without effective microbial treatment was higher than the types given EM. Based on the fertility and clean indices, the treated and untreated municipal solid waste and combined waste compost belonged to class RU-1 and class D, respectively. Moreover, compost prepared from treated and untreated green waste belonged to classes B and C respectively. In general, the prepared CW and GW composts have medium to high fertilizing potential and are fit for domestic as well as commercial use. However, MSW compost is not fit for agricultural purposes as it didn't improve soil fertility to a greater extent but can be used as a soil conditioner in limited quantity as it can cause metal toxicity. For this reason, proper segregation of inputs at the start of a composting process is necessary to improve its quality before being put to agricultural use as any unbalanced or unchecked content of mixed waste will affect the overall compost quality.Implications: Significance of the work: The research dealt with different combinations of segregated wastes to analyze the best fit solid waste compost. Experiments were conducted on the actual landfill site area to simulate the conditions for the process. The manuscript provides evidence and other facts advocating the use of composting for waste management and ultimately reducing pollution caused by landfilling. It ought to cause a multiplier effect if the same is to be followed in other parts of the world, and thus working our way toward getting the Smart city project to fruition. The results of the study exhibit the differences in physiochemical nature of various types of composts. A treatment of microbial consortium with restrictions enabled a conducive atmosphere in the colonies to thrive faster and initiate the process of decomposition. We observed that treated samples converted faster into compost as compared to non-treated samples. We also observed the effect of treatment on fertility parameters of prepared compost samples. In general, it was found that the organic carbon and C/N ratio declined while the total nitrogen and total potassium was observed to increase with very little to no change in phosphorous content, with the inoculation of beneficial micro-organisms throughout the composting course. A reduction in the heavy metal levels was observed in samples treated with active micro-organisms. The compost classification into A, B, C, and D classes represents the quality of compost and further use in agricultural land on commercial levels. The quality index values were determined highest for green waste compost (GWC). The municipal solid waste compost (MSWC) exhibited lowest index values. Therefore, based on the quality index values, the utilization of GWC will aid in reutilizing the green waste and in boosting soil fertility and reduce the waste quantity generation rates. It's also necessary to make compost making widespread among the farmers for a sustainable environment. The GWC has been considered as a sustainable option of waste management, being economically and ecologically viable.

Gender attitude towards environmental protection: a comparative survey during COVID-19 lockdown situation

Attitude towards environmental protection is a crucial component in environmental safeguard psychology. It is a psychological tendency expressed by evaluating the environmental gender attitude with favour or disfavour. This study aimed to compare the attitude level of male and female trainees towards environmental protection based on personal, psychological and sociocultural variables by using an ex post facto research design. The research population was composed of the trainees (N=177) who participated in the online training programmes organized from April 07 to May 31, 2020, by the Centre for Advanced Agricultural Science and Technology (CAAST) for Climate Smart Agriculture and Water Management (CSAWM), MPKV, Rahuri, Maharashtra, during COVID-19 lockdown period. In this study, an online survey method was used. The research instrument was a well-designed and structured online questionnaire using a Google Form consisting of two sections. The first section consisted of 11 independent variables of personal, psychological and sociocultural characteristics. The second section consisted of 17 environmental attitude questions focusing on closed structure questions with a five-point Likert scale, i.e. Strongly Agree to Strongly Disagree. The results revealed that age, training received, membership of environmental societies or organizations, courses taught, waste management and social media use significantly affect the trainees' attitudes to environment protection. The female respondents had a favourable environmental attitude when compared with the male respondents. Therefore, the study concluded that a set of factors influences the gender attitude of the online trainees. These factors alone cannot change trainees' attitudes towards environmental protection. Accordingly, necessary and appropriate conditions should be provided to change the attitude of male trainees for environmental protection. Sustained support is necessary to efficiently understand the role of gender in environment protection through government policies, social media, policymakers, scientists, extension workers, research organizations, various training programmes, participation of students and faculty in the environmental cleanliness drive and awareness programs, etc.

Assessment of mobility and environmental risks associated with copper, manganese and zinc in soils of a dumping site around a Ramsar site

This study reports the environmental fate and ecological hazard of the three heavy metals (HMs), viz. copper (Cu), manganese (Mn) and zinc (Zn) in soil influenced by municipal solid waste (MSW) dumping. The experimental site is situated in the vicinity of Deepor Beel, a Ramsar site located in Guwahati, India. This study assessed (i) the distribution pattern of Cu, Mn and Zn in six geochemical fractionations; (ii) the mobility, bioavailability and toxicity of Cu, Mn and Zn based on eight contamination and ecological indices, and (iii) the impact of Cu, Mn and Zn on soil quality. Altogether, 18 soil samples were collected and analysed from the study site using stratified random sampling. Pollution indices and multivariate statistics were applied on the data to identify the level and source of analysed HMs. Sequential extraction has revealed that the binding strength of Cu, Mn and Zn had a uniform trend. Mobility and potential bioavailability of studied HMs were in the order Mn > Cu > Zn. Analysed HMs were dominantly associated with non-bioavailable fractions. The observed low values of various contamination factors indicated the lesser contamination load posed by these metals. Conversely, their high enrichment factor and geo-accumulation index values indicated the sources of these metals were anthropogenic. Overall, the pollution and ecological indices registered lower contamination. Yet, it would be prudent to adopt efficient MSW management strategies for eliminating any future risk emanating out of this dumping site and posing threat to nearby Deepor Beel and its associated flora and fauna.

Effects on soil phosphorus dynamics of municipal solid waste compost addition to a burnt and unburnt forest soil

The main aim of this research was to assess the effects of municipal solid waste compost (MSWC) addition to a burnt and unburnt calcareous soil, on the distribution of soil P forms in particle-size and extractable fractions. Three MSWC doses (1, 2 and 4% w/w) were added to burnt and unburnt soil samples and were incubated for 92 days at 29 °C and 75% of field capacity moisture. A particle-size fractionation followed by a sequential P extraction procedure was carried out. The burnt soil showed significantly lower concentrations of organic P forms (P_org) and significantly higher concentrations of stable P forms than the unburnt soil. Besides, in both burnt and unburnt soils, most P-forms presented higher concentrations in the clay fractions than in the sand and silt fractions, possibly due to the different proportions of microbial synthesized and plant-derived substances in the different particle-size fractions. Finer fractions of MSWC showed higher total P and P_org concentrations than coarser fractions. Our results showed that the highest dose of MSWC` was the most effective one for the rehabilitation of the burnt soil. MSWC amendment also caused an increase in soil P availability in the unburnt soil which initially contained relatively low levels of P. During the incubation process, a high proportion of organic P contained in the MSWC was mineralized into inorganic P forms. These forms were precipitated with Ca cations which are very abundant in these calcareous soils, significantly increasing the P fraction extracted by HCl in both amended soils. Hence, adding compost to the soil involved an increase in the available P reservoir in the long term. The combination of particle-size fractionation, chemical sequential extraction and incubation experiments can be a valuable tool for splitting soil phosphorus into different fractions regarding their availability in relation to short and long-term transformations in soil.

Challenges and opportunities associated with waste management in India

India faces major environmental challenges associated with waste generation and inadequate waste collection, transport, treatment and disposal. Current systems in India cannot cope with the volumes of waste generated by an increasing urban population, and this impacts on the environment and public health. The challenges and barriers are significant, but so are the opportunities. This paper reports on an international seminar on 'Sustainable solid waste management for cities: opportunities in South Asian Association for Regional Cooperation (SAARC) countries' organized by the Council of Scientific and Industrial Research-National Environmental Engineering Research Institute and the Royal Society. A priority is to move from reliance on waste dumps that offer no environmental protection, to waste management systems that retain useful resources within the economy. Waste segregation at source and use of specialized waste processing facilities to separate recyclable materials has a key role. Disposal of residual waste after extraction of material resources needs engineered landfill sites and/or investment in waste-to-energy facilities. The potential for energy generation from landfill via methane extraction or thermal treatment is a major opportunity, but a key barrier is the shortage of qualified engineers and environmental professionals with the experience to deliver improved waste management systems in India.

Characterization of municipal solid waste in high-altitude sub-tropical regions

Solid waste management (SWM) is one of the most challenging issues owing to lack of authentic data on different elements of SWM, namely, storage, collection, transportation, separation, processing and disposal. This study presents an assessment of existing status of SWM in conjunction with municipal solid waste (MSW) generation rates, physical and chemical characterization of MSW in high-altitude sub-tropical regions. Weighing of empty and fully loaded trucks per trip revealed total quantity of MSW collected. The average efficiency of MSW collection was 70%. From the baseline data, it is inferred that the population and MSW generation rates are not co-related. The collected MSW included biodegradables (organic wastes), paper, plastic, glass, ceramics, metals, inert materials, ash and debris. The data analysis indicated that the biodegradable components dominate the characterization at 54.83% followed by inert, ash and debris at 21.06%, paper at 8.77%, plastic at 8.18%, glass and ceramics at 4.45% and metals at 2.71%. Statistical measures were also applied and 90% confidence interval (CI) was generated for the characterization data measuring its statistical significance.