A simple tandem bioassay-guided SCX-RP SPE fractionation for efficient active peptide screening from Inca nut cake protein hydrolysate

Typically, bioactive peptides were uncovered from complex hydrolysates using sequential bioassay-guided fractionation. To increase the efficiency of bioactive peptide screening, a simple and convenient tandem bioassay-guided fractionation based on solid-phase extraction (SPE) was conducted to screen the angiotensin-I-converting enzyme (ACE) inhibitory peptides from the hydrolysate of Inca nut cake protein (INCP). The so-called SCX-RP SPE system was constructed by assembling SCX (strong cation exchange) and RP (reversed phase) SPE cartridges. Using this tandem SCX-RP SPE, the INCP digested with combined gastrointestinal protease (INCP GP) was fractionated into 30 fractions. The fraction F11 exhibited the highest ACE inhibitory activity among 30 fractions. The ACE IC50 of fraction F11 was calculated to be 6.6 ± 0.5 µg/mL. The ACEI activity of fraction F11 was stronger than the INCP GP hydrolysate (ACE IC50 of 12.7 ± 0.4 µg/mL). The tandem SCX-RP SPE fractionation reduced the number of ACE inhibitory (ACEI) peptide candidates from 127 peptides in the INCP GP hydrolysate to only ten peptides in fraction F11. Subsequently, WALPTQSW (WW-8) and WLPTKSW (WW-7) from fraction F11 were synthesized, and their ACE IC50 was determined to be 4.7 ± 0.1 and 7.9 ± 0.1 µM, respectively. The dipeptidyl peptidase-4 (DPP4) inhibitory and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activities of WALPTQSW (WW-8) were also explored to give IC50 values of 131.7 ± 5.2 and 191.8 ± 7.0 µM, respectively. The molecular docking and inhibition mechanism studies indicated that WW-8 inhibited ACE and DPP4 as competitive and non-competitive inhibitors, respectively. The pre-incubation experiment of WW-8 toward ACE and DPP4 demonstrated that WW-8 was a true-inhibitor type. Additionally, the amount of WW-8 was quantified to be 5.8 ± 0.2 and 35 ± 0.4 µg per milligram hydrolysate and fraction F11, respectively. This study demonstrated tandem bioassay-guided SCX-RP SPE fractionation efficiently screened ACEI peptide derived from INCP GP hydrolysate, adding more value to Inca nut cake (a leftover of the oil industry) as a bioactive peptide precursor.

Interchangeable modular design and operation of photo-bioreactors for Chlorella vulgaris cultivation towards a zero-waste biorefinery

This study explores diverse cultivation modes for Chlorella vulgaris within a biorefinery at pilot scale that produces both biodiesel by transesterification of waste frying oils and syngas by gasification of organic wood waste. Given microalgae's comparatively modest biofuel yield relative to principal biorefinery products, the microalgae cultivation process is designed on the biofuels production rates. Liquid and gaseous waste streams are recycled inside the biorefinery: crude glycerol is mixed with wood to enhance the quality of syngas, wastewater is fed to microalgae so as flue gas. Also, the oil extracted from microalgae contributes to produce biodiesel and the waste cells are gasified. Considering that the optimal fit for each cultivation mode varies with the shape of the reactor, we propose a modular approach to assemble them in batteries of tubular, bubble flow, and airlift reactors, and present an operating design criterion that can fulfill the mass balance of the plant by adding/transforming the number of units inside the different batteries. Methods to adjust the operating conditions and control the operating parameters are also discussed. The designed configurations were operated recycling nominal waste streams of about 30 L d-1 of wastewater and 90 Nm3 h-1 of flue gas. Results confirm that the most advantageous one, in terms of volume per recycled waste streams, is a battery of 16 airlift reactors, operating in mixotrophic mode, with growing rate of 0.427 d-1, yield of 3.06, glycerol conversion 39 %, CO2 removal 64 % of inlet 6-10 %(mol) concentration. The same nominal waste streams can also be managed by 40 tubular reactors in almost heterotrophic conditions coupled with 12 bubble columns in autotrophic conditions; working respectively at growing rates of 0.395 d-1 and 0.362 d-1 and yields of 2.94 and 2.84. The battery of tubular reactors reached a glycerol conversion of 45 % and the array of bubble columns removed about 51 % of inlet 12-20 %(mol) CO2 concentration. A complete comparison is reported also in terms of dimensionless numbers and pumping/mixing requirements.

Method development and empirical research in examining the construction of China's "Zero-waste Cities"

At the current stage, >100 cities in China are in the process of constructing "Zero-waste Cities" (ZCs). However, the absence of a unified quantitative evaluation method hinders the real-time display, assessment, and analysis of the progress and effectiveness of construction in various cities. Based on China's "Zero-waste City" (ZC) construction index system, a five-dimensional evaluation approach of transforming the city's construction index system into an evaluation index system is proposed, and an evaluation method for examining the construction of China's ZCs is developed. Meanwhile, the obstacle analysis model is employed to identify ZC's advantages and weaknesses. Following this evaluation framework, empirical research was conducted on Shenzhen. Results showed: 1) Shenzhen's ZC scoring result increased significantly from 58.9 to 108.3 by implementing the pilot project; 2) The dimensions of Management Measure, Support Capacity, and City Characteristic had achieved or approached full scores, but the dimension of Management Level still need improvement. 3) While industrial waste management reached an excellent level and agricultural waste proved manageable, domestic waste landfill and construction waste disposal still existed challenges. This method takes into account the uniformity of evaluation methods in nationwide and the diversity of solid waste environmental issues in cities. It can achieve a quantitative assessment of the ZC construction level for all cities in China, and providing a scientific basis for the horizontal comparison of the construction effectiveness of each city.

Synergistic interaction between hydrocolloids and kinnow peel biowaste for the development of edible fillers using response surface methodology

Rapidly rising societal awareness about the planet sustainability through developing environmentally friendly and biodegradable alternatives to current impact of plastics waste represents an emerging need for establishing a circular bioeconomy of cleaner, safer, greener, and sustainable future. Until now, no investigation has been done on edible tableware made from leftover fruit peels. Presently, Kinnow mandarin is the most commercially farmed citrus fruit commodity, with the highest production, productivity, and popularity among all horticulture crops worldwide, generating vast quantity of peels ending up as putrefying biowaste that impacts ecosystem health. Sustainable efforts are therefore required in the circular economy to develop a creative and comprehensive strategy to address aforementioned issues, raising profitability, enhancing processing efficiency, and exploring "taste over waste," which contributes to overall sustainability. Therefore, in the current study, we established an approach for transforming the citrus peels biowaste into food-related end products by creating edible fillers, which is a sustainable material in terms of its functional, physical, and microbiological qualities for holding of confectionery products. The optimum level of independent variables with maximum desirability were found to be 0.75% calcium chloride concentration, 1.01% agar concentration, and 10% moisture content. A significant (p < 0.05) effect of process parameters was found in all responses. Model validation revealed that the model developed was accurate, with a prediction error ranging from - 9.96 to 3.28%. The technology developed for biowaste-based biofillers is still in a nascent stage, and it is expected that significant advancements will be made in the bio-refinery industries that can make edible fillers a reality in the future and might be helpful in contributing towards sustainable development. This research also demonstrated an efficient and novel approach towards a "zero-waste."

Exploration of characteristics and synthesis gas suitability for heat generation of coffee biomass pellets produced by single and co-pelletization

Production of coffee beans generates various types of biomass that can be applied as bioenergy for drying and roasting the beans. Thus, the aims of this study were to explore the characteristics of coffee biomass pellets (CBPs) produced from coffee cherry pulp (CCP), coffee parchment (CPM), and expired green coffee beans (ECB) by single and co-pelletization. The CBPs were then used to produce the synthesis gas in a downdraft gasifier, and the syngas properties were investigated for further heat applications. The results showed that single and co-pelletization of CCP and CPM performed well. The CBPs had good physiochemical properties in shape, size, and atomic ratios. The higher heating value and energy density of CBPs were 19.25-24.29 MJ/kg and 12.09-14.87 GJ/m3. The ash from CBPs was rich in K2O, CaO and MgO oxides, and the CPM ash had the lowest initial deformation temperature at 1136 °C. The ash samples from CBPs also had different slagging and fouling indexes. The syngas from CBPs mainly contained H2 (6.85-9.30%), CO (12.15-18.85%), and CO2 (10.85-13.75%). The heating value and tar concentration of syngas from CBPs were 3.24-4.32 MJ/m3 and 21.75-30.92 g/m3. The main chemical compounds in tar were styrene, phenol, caffeine, and pyrrole according to GC-MS. These results indicate that CCP and CPM have potential for pelletization and gasification to generate heat needed for coffee bean processing.

Algae-based approaches for Holistic wastewater management: A low-cost paradigm

Aquatic algal communities demonstrated their appeal for diverse industrial applications due to their vast availability, ease of harvest, lower production costs, and ability to biosynthesize valuable molecules. Algal biomass is promising because it can multiply in water and on land. Integrated algal systems have a significant advantage in wastewater treatment due to their ability to use phosphorus and nitrogen, simultaneously accumulating heavy metals and toxic substances. Several species of microalgae have adapted to thrive in these harsh environmental circumstances. The potential of algal communities contributes to achieving the United Nations' sustainable development goals in improving aquaculture, combating climate change, reducing carbon dioxide (CO2) emissions, and providing biomass as a biofuel feedstock. Algal-based biomass processing technology facilitates the development of a circular bio-economy that is both commercially and ecologically viable. An integrated bio-refinery process featuring zero waste discharge could be a sustainable solution. In the current review, we will highlight wastewater management by algal species. In addition, designing and optimizing algal bioreactors for wastewater treatment have also been incorporated.

Data on exopolysaccharides produced by Bacillus spp. from cassava pulp with antioxidant and antimicrobial properties

This data evaluated the capacity of Bacillus spp. isolated from Thai milk kefir to produce exopolysaccharide (EPS) on cassava pulp and tested its antioxidant and antibacterial properties. Thailand's starch industry generates million tons of cassava pulp, which is underutilized or bio-transformed into higher-value bioproducts. Antioxidant and antibacterial bacterial exopolysaccharides are beneficial in the food, feed, pharmaceutical, and cosmetic industries. Moisture, ash, fat, protein, fiber, starch, sugar, neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL) were analyzed from cassava pulp as an EPS substrate. After 3 days of bacterial fermentation, EPS generation, culture pH, reducing sugar amount, and bacterial count were recorded. Antioxidant activities and bioactive content including hydroxyl radical scavenging activity, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, ferric reducing antioxidant power (FRAP), total phenolic and flavonoid content (TPC and TFC), and antimicrobial activity against two Nile tilapia pathogens (Streptococcus agalactiae and Staphylococcus aureus) from different Bacillus species were evaluated. Proximate analysis, dinitrosalicylic acid assay, pH value record, bacterial count using spread plate method, antioxidant activity and bioactive content assays via spectrophotometry, and agar disk diffusion were the main approaches. This study used microbial cell factories to convert agro-biowaste, such as cassava pulp, into EPS bioproducts which accords with a bio-circular green economy model.

Decarbonization in waste recycling industry using digitalization to promote net-zero emissions and its implications on sustainability

Digitalization and sustainability have been considered as critical elements in tackling a growing problem of solid waste in the framework of circular economy (CE). Although digitalization can enhance time-efficiency and/or cost-efficiency, their end-results do not always lead to sustainability. So far, the literatures still lack of a holistic view in understanding the development trends and key roles of digitalization in waste recycling industry to benefit stakeholders and to protect the environment. To bridge this knowledge gap, this work systematically investigates how leveraging digitalization in waste recycling industry could address these research questions: (1) What are the key problems of solid waste recycling? (2) How the trends of digitalization in waste management could benefit a CE? (3) How digitalization could strengthen waste recycling industry in a post-pandemic era? While digitalization boosts material flows in a CE, it is evident that utilizing digital solutions to strengthen waste recycling business could reinforce a resource-efficient, low-carbon, and a CE. In the Industry 4.0 era, digitalization can add 15% (about USD 15.7 trillion) to global economy by 2030. As digitalization grows, making the waste sector shift to a CE could save between 30% and 35% of municipalities' waste management budget. With digitalization, a cost reduction of 3.6% and a revenue increase of 4.1% are projected annually. This would contribute to USD 493 billion in an increasing revenue yearly in the next decade. As digitalization enables tasks to be completed shortly with less manpower, this could save USD 421 billion annually for the next decade. With respect to environmental impacts, digitalization in the waste sector could reduce global CO₂ emissions by 15% by 2030 through technological solutions. Overall, this work suggests that digitalization in the waste sector contributes net-zero emission to a digital economy, while transitioning to a sustainable world as its social impacts.

The rising phenomenon of circular cities in Japan. Case studies of Kamikatsu, Osaki and Kitakyushu

Japan has a culture of appreciating nature, but Japan is the 7th biggest waste producer of OECD (Organisation for Economic Co-operation and Development) countries, as it only recycles 19,6 %, deposits 1 % in landfills, and incinerates the rest. Japan also has one of the lowest rates (20 %) of renewable energy of OECD countries, and recently has decided to reactivate nuclear power plants. In contrast, cases of local circular economy initiatives are increasing in Japan. This suggests an opportunity for progress towards more ambitious circular economy goals. Circular Cities (CC) embrace the principles of the circular economy (CE) by managing resources to minimize waste, maximize efficiency, and promote sustainability. The idea of circular cities is taking hold in the country. This work assesses in a top-down approach CC from a general perspective considering the current state of the art, and then, its application to the Japanese scheme to be contrasted within three particular case studies. CC in Japan represents a holistic and sustainable approach that enhances well-being and the economy by using CE principles. It incorporates Japanese cultural attributes and the necessary stakeholders' involvement to maximize closed loops, reduce resource consumption, and establish a regenerative society. The paper recognizes current progress towards circularity in Japan's cities, towns, and villages, even though they may not call themselves "circular cities" per se. The paper proposes a definition for circular cities specifically for Japan. It analyses three case studies: Kamikatsu, Osaki, and Kitakyushu, urban areas with very different circumstances as examples of circular cities, with the final goal to provide recommendations to policymakers to help increase the circular cities phenomenon.

Full components conversion of lignocellulose via a closed-circuit biorefinery process on a pilot scale

This study developed a closed-circuit biorefinery process for full conversion of lignocellulose into ethanol, biogas and organic fertilizer with zero waste on a pilot scale. In the process, subcritical water pretreatment could effectively break the structure of wheat straw (WS), and ethanol was obtained from pretreated wheat straw (PWS) using two batches of simultaneous saccharification and fermentation (SSF). The pretreatment and ethanol fermentation wastes were reused for biogas and organic fertilizer production by anaerobic digestion (AD), whereas the pretreatment and ethanol conversion efficiency were reduced when supernatant after AD was recovered for next batch pretreatment. The yields of ethanol (0.08-0.09 g/g), biogas (0.05-0.10 L/g) and organic fertilizer (0.55-0.79 g/g) were demonstrated through mass balance. Furthermore, the hidden problems were exposed on pilot-scale conversion process, and several strategies were provided for optimizing the biorefinery process in the future.

Sustainable approach for valorization of solid wastes as a secondary resource through urban mining

The incessant population has increased the production and consumption of plastics, paper, metals, and organic materials, which are discarded as solid waste after their end of life. The accumulation of these wastes has created growing concerns all over the world. However, conventional methods of solid waste management i.e., direct combustion and landfilling have caused several negative impacts on the environment (releasing toxic chemicals and greenhouse gases, huge land use) besides affecting human health. Therefore, it is requisite to determine sustainable alternative technologies that not only help in mitigating environmental issues but also increase the economic value of the discarded solid wastes. This process is known as urban mining where waste is converted into secondary resources and thereby conserves the natural primary resources. Thus, this review highlights the technological advancements in the valorization process of discarded wastes and their sustainable utilization. We also discussed several limitations of the existing urban mining processes and further the feasibility of valorization techniques was critically analyzed from a techno-economical perspective. This paper recommends a novel sustainable model based on the circular economy concept, where waste is urban mined and recovered as a secondary resource to support the united nations sustainable development goals (SDGs). The implementation of this model will ultimately help the developing countries to achieve the target of SDGs 11, 12, and 14.

Characterization of a natural biodegradable edible film obtained from arrowroot starch and iota-carrageenan and application in food packaging

Future food packaging trends are shifting to natural and eco-friendly materials developed from biopolymers such as starch and other hydrocolloids, to reduce pollution from synthetic polymers. Arrowroot starch (AS) (3.5, 3, 2.5, and 2%) and iota-carrageenan (IC) (0.5, 1, 1.5, and 2%) were blended to develop biodegradable edible films (AS/IC-BEF), which were compared against AS-BEF (4%, control). All films were characterized based on their physico-mechanical and barrier properties, functional group properties, crystallinity properties, thermal properties, and soil and seawater biodegradation. AS-BEF exhibited smooth surface, high transparency, and completed composting soil biodegradation in 7 days whereas AS/IC-BEF samples exhibited higher tensile strength, water solubility, swelling properties, and barrier properties, but completed biodegradation after 30 days. XRD analysis indicated IC fractions contributed to increase in degree of crystallinity (28.35°) and FTIR signaled strong hydrogen bond interactions between polymers. AS/IC-BEF samples demonstrated melting temperatures between 158 and 190 °C while glass transition temperatures ranged from 153 to 176 °C, which resulted in maximum weight loss around 50-55% at melting temperatures. Finally, AS/IC-BEF samples successfully inhibited weight loss of cherry tomatoes at room temperature and extended their shelf life to 10 days, which indicated that the AS/IC composite material produced a BEF with potential food and industrial applications.

Macrophytes as wastewater treatment agents: Nutrient uptake and potential of produced biomass utilization toward circular economy initiatives

Macrophytes have been widely used as agents in wastewater treatment. The involvement of plants in wastewater treatment cannot be separated from wetland utilization. As one of the green technologies in wastewater treatment plants, wetland exhibits a great performance, especially in removing nutrients from wastewater before the final discharge. It involves the use of plants and consequently produces plant biomasses as treatment byproducts. The produced plant biomasses can be utilized or converted into several valuable compounds, but related information is still limited and scattered. This review summarizes wastewater's nutrient content (macro and micronutrient) that can support plant growth and the performance of constructed wetland (CW) in performing nutrient uptake by using macrophytes as treatment agents. This paper further discusses the potential of the utilization of the produced plant biomasses as bioenergy production materials, including bioethanol, biohydrogen, biogas, and biodiesel. This paper also highlights the conversion of plant biomasses into animal feed, biochar, adsorbent, and fertilizer, which may support clean production and circular economy efforts. The presented review aims to emphasize and explore the utilization of plant biomasses and their conversion into valuable products, which may solve problems related to plant biomass handling during the adoption of CW in wastewater treatment plants.

Cost benefit analysis of a municipal solid waste recycling facility in Soweto, South Africa

Rapid population and economic growth, changes in consumption pattern etc. have become major contributing factors to severe municipal solid waste generation globally. Thus, various methods are being employed to manage the incessant municipal solid waste generation for a sustainable solid waste management and one of the viable approaches is the recycling option. The main objective of this paper is to determine the cost benefit analysis of setting up a recycling facility for the processing of various wastes for use as raw materials by industries. The cost benefit analysis was carried out based on historic data obtained from the municipality and some recent waste composition data. The overall analysis was done using Excel software. From the Excel software analysis, Internal Rate of Return on investment was 42%, Internal Rate of Return on equity was 98% and Net Present Value was R 63, 420,000 (USD$ 4646225.33). In ascertaining the result obtained from the Microsoft Excel, three data analysis and technical computing software (MATLAB, Python, and R-Studio) were employed. This was necessary to compare and validate the cost-benefit indicators (Net Present Value and Internal Rate of Return). Besides, evaluating the performance of each software with regards to the cost-benefit evaluation is ideal for a recycling plant like this to establish the feasibility of the project. Moreover, sensitivity analysis was conducted, and a breakeven point of 211 tons of waste was obtained. In addition, the total benefit of recycling was valued and was given as R 486,008,582.85 (USD$ 35605572.16). From the overall analysis, it was observed that the IRR and Net Present Value were alike, about 677 potential jobs could be created on the project and the Net Present Value > 0. Based on the overall analysis, it was concluded that the project is viable.

Valorization of microalgae biomass into bioproducts promoting circular bioeconomy: a holistic approach of bioremediation and biorefinery

The need for alternative source of fuel has demanded the cultivation of 3rd generation feedstock which includes microalgae, seaweed and cyanobacteria. These phototrophic organisms are unique in a sense that they utilise natural sources like sunlight, water and CO₂ for their growth and metabolism thereby producing diverse products that can be processed to produce biofuel, biochemical, nutraceuticals, feed, biofertilizer and other value added products. But due to low biomass productivity and high harvesting cost, microalgae-based production have not received much attention. Therefore, this review provides the state of the art of the microalgae based biorefinery approach to define an economical and sustainable process. The three major segments that need to be considered for economic microalgae biorefinery is low cost nutrient source, efficient harvesting methods and production of by-products with high market value. This review has outlined the use of various wastewater as nutrient source for simultaneous biomass production and bioremediation. Further, it has highlighted the common harvesting methods used for microalgae and also described various products from both raw biomass and delipidified microalgae residues in order to establish a sustainable, economical microalgae biorefinery with a touch of circular bioeconomy. This review has also discussed various challenges to be considered followed by a techno-economic analysis of the microalgae based biorefinery model.

Evaluating emissions reductions from zero waste strategies under dynamic conditions: A case study from Boston

In 2018 and 2019 the City of Boston (Massachusetts, USA) conducted zero waste and carbon neutral planning efforts. Here we present the results of an accompanying analysis of the impacts of zero waste strategies on greenhouse gases (GHG) emissions associated with waste treatment. Emissions analysis in the waste sector is complicated by the contribution of significant indirect impacts that can exhibit temporal and spatial heterogeneity. For example, lifecycle GHG analysis of waste-to-energy combustion grants credits for the emissions avoided due to electricity generated from organic waste (biogenic carbon) that displaces electricity generation that could be carbon-emitting. As electricity grids decarbonize, this credit approaches zero. Long-term emissions planning needs to account for such dynamics to realistically assess the GHG mitigation potential associated with alternative waste management strategies. Here, we seek to capture these dynamics in a forward-looking analysis of waste sector emissions under a zero-waste strategy for the City of Boston. Using publicly available data sets such as EPA's Waste Reduction Model (WARM), we show that the implementation of zero waste strategies reduces the combustion of plastics and biomass in waste-to-energy (WtE) combustion facilities and associated GHG emissions. While WtE has been considered less-carbon intensive than other forms of waste treatment and fossil-based electricity generation, our analysis shows that more renewables will eventually eliminate the perceived GHG benefits associated with waste-to-energy combustion. While our approach provides policymakers with an understanding of the impacts of decisions in a dynamic context, we also identify common knowledge gaps in conducting forward-looking waste-GHG assessments.

Strategies for fortified sustainable food: the case of watermelon-based candy

The aim of this research was to design a new product, in particular a watermelon-based jelly candy, without generating waste. The study was divided in two steps: (i) optimization of candy formulation in terms of amount of rind, pulp and juice; (ii) fortification of the jelly candy with different concentrations of orange by-products (albedo and flavedo flours). The fortified jelly samples were assessed for sensory quality and chemical properties, before and after digestion. The new candy product was greatly appreciated. The addition of albedo and flavedo flours significantly improved the chemical composition compared to jelly candy without by-products, before and after digestion. A whole quality index was also calculated to determine the best combination of by-products to be added. Fortification with albedo 1.2% and flavedo ranged between 0.6 and 1.2% allowed recording the most interesting jelly candy.

Walking the talk: The responsibility of the scientific community for mitigating conference-generated waste

An estimated 19-23 million metric tons of global plastic waste reportedly entered aquatic environments in 2016 with mounting evidence that plastic marine debris causes ecological effects across all levels of biological organization in aquatic systems. Scientific conferences generate opportunities for waste through food and beverage services, giveaways, marketing and registration materials, poster and trade exhibits, attendee travel, lodging services, and local transportation. Zero waste measures instituted at the Sixth International Marine Debris Conference resulted in the avoidance of 76,300 single-use items. Zero waste is a process defined by a spectrum of actions ranging from no reduction whatsoever to generation of absolutely no waste. Achieving 100% zero waste is very difficult. Deciding where on the spectrum you wish to land and being comfortable with that target is paramount for event planning. Planning for reduced waste takes time, funding, and determination, but environmentally-themed organizations have a responsibility to lead by example.

Waste services' performance assessment: The case of Tuscany, Italy

This paper assesses the performance of waste services in the region of Tuscany in Italy. It adopts non-parametric techniques for this purpose. Furthermore, it investigates the influence of the operational environment on the estimated performance by using the robust order-m technique. Meaningful levels of inefficiency were found in the Italian waste services. A specification of the ownership of the operator entrusted with waste management by municipalities and the formal adoption of the zero-waste strategy are included as environmental variables. The study concludes that the influence of the operational environment is a determinant of performance. The income per capita is negatively associated with efficiency, while population density is positively associated. Furthermore, efficiency levels are lower for municipalities with higher mixed waste per capita produced. Improving good pro-environmental behaviours is likely to improve efficiency and, thus, tariffs. The empirical results support the idea that it is necessary to make relevant organizational decisions that imply higher costs to increase the refuse collection rate. An increase in the separate collection rate beyond 50% is associated with the reduction of the efficiency level reached. Efficiency analysis does not consider the additional costs and the opportunities for municipalities to get revenues by selling them as secondary raw materials. Besides, the adoption of a zero-waste strategy is related to higher efficiency in MSW service provision. Finally, results about the ownership issue support the idea that privatization is not necessarily associated with the performance improvement of the waste services.

Biodegradable and non-biodegradable fraction of municipal solid waste for multifaceted applications through a closed loop integrated refinery platform: Paving a path towards circular economy

An increase in population, rapid urbanization and industrialization has accelerated the rate of municipal solid waste generation. The current disposal of solid waste is a burgeoning issue and it's in immediate need to shift the existing disposal processes to a sustainable manner. Circular economy (CE) is a conceptual model which is been used for better use of resources and minimization of waste in a closed loop approach which could be appropriate for waste management. In this context, the present review illustrates the effective use of biodegradable and non-biodegradable fraction of solid waste in a closed loop integrated refinery platforms for the recovery of bioenergy resources and for the production of value added products. The biodegradable fraction of solid waste could be treated by advanced biological processes with the simultaneous production of bioenergy such as biohydrogen, biomethane, bioelectricity, etc., and other value added products like butanol, ethanol, methanol etc. The scheme illustrates the closed loop approach, the bioenergy generated from the biodegradable fraction of solid waste could be used for the operation of internal combustion engines and the energy could be further used for processing the waste. The non-biodegradable fraction of solid waste could be used for construction and pavement processes. Overall the study emphasizes the paradigm shift of solid waste management concepts from linear economy to a circular economy following the "Zero Waste" concept. The study also explains the circular economy policies practiced for solid waste management that stimulates the economy of the country and identify the pathways to maximize the local resources. In addition the review addresses the advanced information and communication technologies to unfold the issues and challenges faced in the solid waste management. The smart governance of managing waste using the "Internet of Things" (IoT) is one of the great precursors of technological development that could lead innovations in waste management.

Collection of recyclable wastes within the scope of the Zero Waste project: heterogeneous multi-vehicle routing case in Kirikkale

There is an increase in the amount of resource use due to the rise in population, urbanization, and industrialization. Also, the amount of waste increases due to an increase in consumption and resource use. Countries are developing new policies depending on both decreasing resources and environmental problems caused by waste. The "Zero Waste" project was launched to recycle waste and to reduce environmental pollution in Turkey. The project aims to separate recyclable waste at its source and recycle them. One of the problems encountered in the implementation of the project is collecting the waste from temporary storage areas. In this study, the problem of transportation of wastes from temporary warehouses to the main warehouse was discussed in Kırıkkale/Turkey. A three-step solution approach has been proposed to the solution of the problem. In the first stage, the amounts of waste generated at the addresses to collect were estimated. In the second stage, the addresses to be visited are classified with an approach based on Pareto analysis according to the calculated waste amounts. According to this classification, it is planned which addresses will be visited on which day of the week. At the last stage, the problem is modeled as a heterogeneous multi-vehicle routing problem, which also takes into account the daily working hours and vehicle capacity constraints. According to the result of the mathematical model, the number of vehicles needed for waste collection, the types of vehicles, and the routes of the vehicles were found. Considering the implementation stages of the Zero Waste project, three different case studies are handled for Kırıkkale. These case studies have been solved by considering different waste rates. According to the results, the waste collection plan was made economically by visiting fewer spots in a week.

Municipal solid waste generation and characterization in the City of Johannesburg: A pathway for the implementation of zero waste

The huge increase generation of municipal solid waste (MSW) has recently become an issue of global concern. This is because waste generation increases as the population increases and the management of this waste has equally become a bit difficult. This study aims at determining the characterization and the pattern of municipal solid waste (MSW) in the City of Johannesburg (CoJ), South Africa. The results revealed that plastics and organic wastes constitute the highest waste content in both the daily refuse (DR) and round collected refuse (RCR). The results further showed that DRs are 28% and 26% for plastic wastes, while 28% and 29% organic wastes accounted for the RCRs during the summer and winter seasons respectively. The carbon to nitrogen ratio (C:N) content of the food wastes employed in this study was evaluated to be 22.66 and the empirical equation generated was C₂₇H₄₄NO₁₆. STATA 12 software and ANOVA statistical technique were used to evaluate the seasonal variation between the winter and summer seasons (spanning a space of six months). The p-values obtained for the DR was (p-value = 0.9775) and for the RCR, it was (p-value = 0.9760) at 95% confidence level using STATA 12 tests. Similarly, the p-value obtained for the DR was (p-value = 0.999) and for the RCR, it was (p-value = 0.991) in turn using ANOVA tests at 95% confidence level. Furthermore, Minitab software was used to forecast the trend of waste generation between 2016 and 2025. Based on the overall results, it was concluded that the differences between the wastes generated in both seasons were not statistically significant (p > 0.05). Furthermore, a total of 102,406 tonnes of wastes would be generated during the period under consideration (a period of ten years). This indicates a negative trend for CoJ in terms of waste generation. However, this trend can be mitigated through Zero waste (ZW) implementation.

Toward zero waste events: Reducing contamination in waste streams with volunteer assistance

Public festivals and events generate a tremendous amount of waste, especially when they involve food and drink. To reduce contamination across waste streams, we evaluated three types of interventions at a public event. In a randomized control trial, we examined the impact of volunteer staff assistance, bin tops, and sample 3D items with bin tops, on the amount of contamination and the weight of the organics, recyclable containers, paper, and garbage bins at a public event. The event was the annual Apple Festival held at the University of British Columbia, which was attended by around 10,000 visitors. We found that contamination was the lowest in the volunteer staff condition among all conditions. Specifically, volunteer staff reduced contamination by 96.1% on average in the organics bin, 96.9% in the recyclable containers bin, 97.0% in the paper bin, and 84.9% in the garbage bin. Our interventions did not influence the weight of the materials in the bins. This finding highlights the impact of volunteers on reducing contamination in waste streams at events, and provides suggestions and implications for waste management for event organizers to minimize contamination in all waste streams to achieve zero waste goals.

Production of proteases from organic wastes by solid-state fermentation: downstream and zero waste strategies

Production of enzymes through solid-state fermentation (SSF) of agro-industrial wastes reports high productivity with low investment. The extraction of the final product from the solid waste and solid disposal represent the main cost of the process. In this work, the complete downstream processes of SSF of two industrial residues for the production of proteases, soy fibre (SF) and a mixture of hair and sludge (HS), were studied in terms of activity recovery, using different extraction parameters (extracting solvent, ratio solid: solvent and extraction mode). Activity after lyophilisation was tested. Solid waste valorisation after extraction was studied using respiration techniques and biogas production tests, as part of a zero waste strategy. Results showed a maximum extraction yield of 91% for SF and 121% for HS, both in agitated mode and distilled water as extraction agent. An average activity recovery of 95 ± 6 and 94 ± 6% for SF and HS, respectively, was obtained after lyophilisation and redissolution. To reduce the cost of extraction, a ratio 1:3 w:v solid-solvent in static mode is advised for SF, and 1:2 w:v extraction ratio in agitated mode for HS, both with distilled water as extracting agent. Both composting and anaerobic digestion are suitable techniques for valorisation of the waste material.

Recovery of protein hydrolysate and chitosan from black tiger shrimp (Penaeus monodon) heads: approaching a zero waste process

Shrimp heads are considered as a potential source for the recovery of many valuable components such as chitin, protein and carotenoids. In the present study, both protein hydrolysate and chitin/chitosan were recovered using combination of physical, biological and chemical treatments. Shrimp heads were separated from liquid phase by a facile and efficient physical pretreatment. The liquid fraction was then hydrolyzed using formic acid and vacuum concentrated to obtain an astaxanthin-rich protein hydrolysate. The solid fraction was used to produce chitin by deproteination and demineralization. The hydrolysate consisted of a high astaxanthin (192 ppm) and protein (26.3 wt%) content. Chitosan prepared from chitin showed a high degree of deacetylation (85.4%) with low protein (0.25 wt%) and mineral (0.22 wt%) contents. The relative crystalline structure of the chitin and chitosan were 54.7 and 10.4%, respectively. The deacetylation of chitin was confirmed by Fourier Transform Infrared Spectroscopy. The present procedure approached to produce maximum valuable components including astaxanthin-rich protein hydrolysate and chitin/chitosan from shrimp head waste.

Achieving zero waste of municipal incinerator fly ash by melting in electric arc furnaces while steelmaking

The main objective of this work was to promote zero waste of municipal incinerator fly ash (MIFA) by full-scale melting in electric arc furnaces (EAFs) of steel mini mills around the world. MIFA, generally, is considered as a hazardous waste. Like in many countries, MIFA in Taiwan is first solidified/stabilized and then landfilled. Due to the scarcity of landfill space, the cost of landfilling increases markedly year by year in Taiwan. This paper presents satisfactory results of treating several hundred tons of MIFA in a full-scale steel mini mill using the approach of "melting MIFA while EAF steelmaking", which is somewhat similar to "molten salt oxidation" process. It was found that this practice yielded many advantages such as (1) about 18wt% of quicklime requirement in EAF steelmaking can be substituted by the lime materials contained in MIFA; (2) MIFA would totally end up as a material in fractions of recyclable EAF dust, oxidized slag and reduced slag; (3) no waste is needed for landfilling; and (4) a capital cost saving through the employment of existing EAFs in steel mini mills instead of building new melting plants for the treatment of MIFA. Thus, it is technically feasible to achieve zero waste of MIFA by the practice of this innovative melting technology.

From waste to sustainable materials management: Three case studies of the transition journey

Waste policy is increasingly moving on from the 'prevention of waste' to a 'sustainable materials policy' focused agenda recognising individual wastes as a resource. In order to comparatively analyse policy developments in enhanced waste management, three case studies were selected; San Francisco's Zero Waste Program, Flanders's Sustainable Materials Management Initiative and Japan's Sound Material-Cycle Society Plan. These case studies were chosen as an opportunity to investigate the variety of leading approaches, governance structures, and enhanced waste policy outcomes, emerging globally. This paper concludes that the current transitional state of waste management across the world, is only in the first leg of the journey towards Circular Economy closed loop production models of waste as a resource material. It is suggested that further development in government policy, planning and behaviour change is required. A focus on material policy and incorporating multiple front runners across industry and knowledge institutions are offered as potential directions in the movement away from end-pipe land-fill solutions.

Sewage sludge ash (SSA) from large and small incineration plants as a potential source of phosphorus - Polish case study

The aim of this research is to present the possibility of using the sewage sludge ash (SSA) generated in incineration plants as a secondary source of phosphorus (P). The importance of issues related to P recovery from waste materials results from European Union (UE) legislation, which indicated phosphorus as a critical raw material (CRM). Due to the risks of a shortage of supply and its impact on the economy, which is greater than other raw materials, the proper management of phosphorus resources is required in order to achieve global P security. Based on available databases and literature, an analysis of the potential use of SSA for P-recovery in Poland was conducted. Currently, approx. 43,000 Mg/year of SSA is produced in large and small incineration plants and according to in the Polish National Waste Management Plan 2014 (NWMP) further steady growth is predicted. This indicates a great potential to recycle phosphorus from SSA and to reintroduce it again into the value chain as a component of fertilisers which can be applied directly on fields. The amount of SSA generated in installations, both large and small, varies and this contributes to the fact that new and different P recovery technology solutions must be developed and put into use in the years to come (e.g. mobile/stationary P recovery installations). The creation of a database focused on the collection and sharing of data about the amount of P recovered in EU and Polish installations is identified as a helpful tool in the development of an efficient P management model for Poland.

Toward zero waste: composting and recycling for sustainable venue based events

This study evaluated seven different waste management strategies for venue-based events and characterized the impacts of event waste management via waste audits and the Waste Reduction Model (WARM). The seven waste management scenarios included traditional waste handling methods (e.g. recycle and landfill) and management of the waste stream via composting, including purchasing where only compostable food service items were used during the events. Waste audits were conducted at four Arizona State University (ASU) baseball games, including a three game series. The findings demonstrate a tradeoff among CO2 equivalent emissions, energy use, and landfill diversion rates. Of the seven waste management scenarios assessed, the recycling scenarios provide the greatest reductions in CO2 eq. emissions and energy use because of the retention of high value materials but are compounded by the difficulty in managing a two or three bin collection system. The compost only scenario achieves complete landfill diversion but does not perform as well with respect to CO2 eq. emissions or energy. The three game series was used to test the impact of staffed bins on contamination rates; the first game served as a baseline, the second game employed staffed bins, and the third game had non staffed bins to determine the effect of staffing on contamination rates. Contamination rates in both the recycling and compost bins were tracked throughout the series. Contamination rates were reduced from 34% in the first game to 11% on the second night (with the staffed bins) and 23% contamination rates at the third game.