1,720,964 research outputs found
Wastewater treatment using black soldier fly larvae: Influence of larval density and solid support
Full text linkThe use of Black Soldier Fly larvae for wastewater treatment has emerged as a promising alternative, coupling high removal efficiency with recovery of high-value products. To overcome the critical issue of larvae mortality in a liquid environment, a patented solution employs a physical porous support to be saturated by liquid, allowing larvae mobility. In view of process optimisation, a knowledge gap persists regarding both the optimal supporting material and larval density. The optimum supporting material and larval density should maximise the porosity (i.e. active volume of the reactor) and the removal efficiencies respectively, without compromising the survival rate. In the present study, three different plastic products (granules, pall rings and geomat) were tested at four different larval densities (4, 8, 16 and 32 larvae/cm(2)). Process performance was compared in terms of larval growth and substrate removal. An increase in larval density only impairs process once threshold density is exceeded. The threshold depended on the supporting material: higher porosity materials allow the use of higher larval densities, and therefore higher organic loads, with reduced reactor volumes. The best performance was achieved at larval density of 16 larvae/cm(2) with pall rings, resulting in a survival rate and carbon removal efficiency of approx. 92 % and 97 % respectively
Final quality of a sustainable landfill and postclosure management
Full text linkLandfill should be designed and constructed in line with the principle of environmental sustainability, guaranteeing over a period of less than one generation (typically considered 30 years) the environmental equilibrium of Final Storage Quality, when waste stability and immobilisation of contaminants is achieved and all active measures of control may be removed without posing any further risk to the environment. The practical definition of FSQ, when a landfill can be released from aftercare, and a procedure for the technical and administrative termination of the post-closure management phase are an evident regulatory strategic need to assure the design of sustainable landfill. The aim of this paper is to provide a criterion to define the FSQ of landfill, based on the control of the analytical emission parameters and of stability indexes related to the residual emission potential. These should concur with the law’s acceptance criteria for the landfilling of wastes (LAC), and with the legal limit values (LLV) established for the emission of contaminants into the environment. The interrelationship between, stability indexes (emission potential), analytical emission parameters, LAC and LLV is discussed and reference values are provided. Finally, the paper proposes a procedure for the termination of technical and administrative aspects following the post-closure management in accordance with FSQ
Problems in traditional landfilling and proposals for solutions based on sustainability
Full text linkIn recent years, the Circular Economy has become the key lynchpin underlying the waste management system. However, the emphasis placed on recycling has led, on one hand, to an underestimation of the critical issues that are currently emerging so dramatically (i.e. limited recyclability of materials, instability of markets for secondary raw materials, and accumulation of contaminants present in the recycled materials), whilst on the other to neglect the inescapable role of landfill in waste management. In many cases, landfills are seen as a simple and economical means of disposing of waste, and from a political, legislative and technical viewpoint they are frequently denied the attention devoted to other engineering works, lacking ade-quate financial investment to cover the costs required to ensure a sustainable landfill system. Landfill should be designed and constructed in line with the principle of environmental sustainability, by adopting technical measures aimed at guaranteeing waste stability and immobilisation of contaminants over a period of less than one generation and ensuring a Final Storage Quality in equilibrium with the environment. This article summarises the concept of sustainable landfilling, identifies the technical strategies that characterise this system, describes the critical issues frequently encountered after decades of operation and proposes a series of solutions aimed to control long-term behavior
Treatment of wastewater using Black Soldier Fly larvae: Effect of organic concentration and load
Full text link: Recent studies have investigated the use of Black Soldier Fly (BSF) larvae as a promising biological treatment process for high organic content wastewater (i.a. Leachate from municipal solid waste landfill, food processing effluents), achieving both high treatment efficiency and production of secondary resources from larval biomass (i.a. Proteins and lipids). The present study was aimed at achieving a better understanding of how organic concentration and load might influence treatment performance. Larvae were fed with three artificial wastewaters characterised by same organic substances quality (degree of biodegradability and oxidation of the organic content measured respectively as BOD/COD and TOC/COD ratios) but different organic concentrations. Each type of wastewater was tested at four different loads. Treatment performance was assessed by monitoring both larval growth (in terms of weight variation, mortality and prepupation), and variation of wastewater quality and quantity to determine organic substrate consumption (measured in terms of Total Organic Carbon, TOC). Larval starvation was observed in all tests when TOC concentrations dropped below approx. 1000 mg C/L, which, for the tested wastewater, could be assumed as the limit value for adopting BSF larvae process. Substrate concentration in the feed (mgC/L) influenced larval growth (in terms of maximum wet weight, prepupation and mortality) only when organic load was above 10 mgC/larva: the higher the load, the higher the positive impact of the substrate concentration. On the contrary, the specific substrate consumption rate (vS, mgC/larva/day) appeared not to be influenced by substrate concentration but only by the organic load, with a Michaelis Menten like relationship. Accordingly, substrate load can be assumed as a design parameter for BSF treatment process, while substrate concentration might only influence potential resource recovery from larval biomass
Potential treatment of leachate by Hermetia illucens (Diptera, Stratyomyidae) larvae: Performance under different feeding conditions
No full textIn this study, the ability of H. illucens larvae (black soldier fly (BSF)) to metabolise different semisolid biowastes (e.g. kitchen waste, animal manure) has been applied to the treatment of landfill leachate. A testing programme has been developed by mixing leachate with three different solid supports: wheat bran, a biodegradable nutrient substrate, brewers’ spent grain, a biodegradable nutrient residue from the brewery industry and sawdust, a low biodegradable residue from the wood industry. Larvae growth rate was monitored in terms of weight variation, mortality and time to reach the prepupal stage. Prepupal biomass composition was analysed in terms of crude protein, lipids and fatty acids. Substrates were monitored at the beginning and the end of tests for total solids (TS), total organic carbon (TOC), total Kjeldahl nitrogen (TKN), ammonia and (whenever significant) the 7-day Respirometric Index (RI7). The best performance was observed with wheat bran and brewers’ spent grain, achieving an average larval weight ranging from 155.1 to 226.1 mg (w/w) with prepupation of more than 80% over 21 days. The initial TS, TOC and nitrogen content in feeding substrates had been metabolised (gasified and accumulated in prepupal biomass) by approximately 55%, 60% and 48%, respectively. Dry mass characterisation displayed a significant content of fats and proteins. The analysis demonstrated the suitability of BSF prepupal biomass for the production of biodiesel; however, the potential use of proteins as an animal feed needs further studies for assessing the presence of contaminants
Biowaste treatment using black soldier fly larvae: Effect of substrate macronutrients on process performance
Full text linkBlack soldier fly larvae (BSFL) process is emerging as a promising alternative for the treatment of biowaste. Process performance (such as survival rate - SR and waste reduction efficiency - RE) depends on several factors (e.g. nutritional quality of the substrate) which need to be controlled. The nutritional quality of the substrate can be related to the overall concentration and relative abundance of dominant macronutrients, such as proteins (P), non-fibre carbohydrates (NFC), and lipids (L). Assessing how these substrate quality parameters influence the process performance is fundamental to determining the suitability of a given substrate to be treated by using BSFL and to optimise the process performance. The aim of this study was to gather, integrate, and elaborate published literature to present a comprehensive understanding of how the nutritional substrate quality, impact the process performance in terms of RE and SR. A systematic literature review was conducted by using the PRI..
The treatment of leachate using Black Soldier Fly (BSF) larvae: Adaptability and resource recovery testing
No full textThe benefits of using Black Soldier Fly (BSF) larvae in biowaste treatment include: commercial value of the stabilized residue, production of biomass rich in fats and proteins, suitable both for biodiesel production and animal feeding. The use of BSF for leachate treatment would introduce a blue low cost solution in the landfill technology, particularly appropriate in developing countries, where landfilling is still widely applied. This paper aimed to investigate the adaptability of BSF larvae to leachate environment, by using different leachate concentrations (25%, 50%, 75%, 100%) and two different feeding substrates: liquid (pure leachate) and semi-solid (wheat bran mixed with leachate). In all tests mortality was less than 50% and it was mainly linked to food shortages: the higher the nutrient content in leachate, the higher the larval development. Dry mass characterisation demonstrate that BSF prepupae biomass can be exploited as an alternative energy source in the production of biodiesel
First worldwide regulation on sustainable landfilling: Guidelines of the Lombardy region (Italy)
Full text linkThe environmental sustainability principle, since the Rio de Janeiro Conference (1992) and the Kyoto Protocol (1997), has produced a marked change in environmental protection strategies. In waste management practices this trend is reflected in the passage from a linear to a circular approach, where strong attention is paid to the recovery of resources from waste, with a dramatic reduction of untreated waste landfilling. Deposition of waste on soil still plays a crucial role in acting as a final sink for closing materials loop in Circular Economy. Paradoxically the regulations of landfilling at international level appear obsolete, not taking into account the environmental sustainability concept, still promoting unsustainable approaches, with environmental protection measures mainly based on physical barriers, without any con-sistent control of long term emissions of contaminants which last longer than the barriers themselves. “Guidelines for Sustainable Design and Management of Land-fills” issued by the Lombardy Region in 2014 represents the first official regulation which introduced systematically the principle of environmental sustainability. They highlight the modern role of landfilling as a final sink and promote measures and procedures for controlling the mobility of the potential contaminants in the waste, until reaching, within a generation time, a Final Storage Quality in equilibrium with the environment. The aim of this paper is to illustrate and discuss the main aspects introduced by the Guidelines, offering an interesting base for a future spread of the practical application of the sustainability concept to landfilling
Preparation of artificial MSW leachate for treatment studies: Testing on black soldier fly larvae process
No full textWhen approaching the study of new processes for leachate treatment, each influencing variable should be kept under control to better comprehend the treatment process. However, leachate quality is difficult to control as it varies dramatically from one landfill to another, and in line with landfill ageing. To overcome this problem, the present study investigated the option of preparing a reliable artificial leachate in terms of quality consistency and representativeness in simulating the composition of real municipal solid waste (MSW) leachate, in view of further investigate the recent treatment process using black soldier fly (BSF) larvae. Two recipes were used to simulate a real leachate (RL): one including chemical ingredients alone (artificial synthetic leachate-SL), and the other including chemicals mixed with artificial food waste (FW) eluate (artificial mixed leachate-ML). Research data were analysed, elaborated and discussed to assess simulation performance according to a series of parameters, such as Analytical representativeness, Treatment representativeness (in this case specific for the BSF larvae process), Recipe relevance, Repeatability and Flexibility in selectively modifying individual quality parameters. The best leachate simulation performance was achieved by the synthetic leachate, with concentration values generally ranging between 97% and 118% of the RL values. When feeding larvae with both RL and SL, similar mortality values and growth performance were observed
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