Cationic polymer-mediated interbacterial aggregation: A novel approach for rapid aerobic granules development.

This study introduces a novel approach to aerobic granular sludge technology that minimizes the start-up time and guarantees the formation of stable granules. This is achieved by seeding the reactor with a cationic polymer without using inoculated sludge. Three cationic polymers (Hydrofloc C4400SA, C8896, and polyelectrolyte emulsion) were tested to determine the most appropriate polymer for aerobic granular sludge (AGS) startup based on the optimal dose and formation of aerobic granules.

Analysis of micro- and nanoplastics in wastewater treatment plants: key steps and environmental risk considerations.

The analysis of micro- and nanoplastics (MNPs) in the environment is a critical objective due to their ubiquitous presence in natural habitats, as well as their occurrence in various food, beverage, and organism matrices. MNPs pose significant concerns due to their direct toxicological effects and their potential to serve as carriers for hazardous organic/inorganic contaminants and pathogens, thereby posing risks to both human health and ecosystem integrity. Understanding the fate of MNPs within wastewater treatment plants (WWTPs) holds paramount importance, as these facilities can be significant sources of MNP emissions.

Effects of inorganic ions on autotrophic denitrification by Thiobacillus denitrificans and on heterotrophic denitrification by an enrichment culture.

Salinity of nitrate-laden wastewaters, such as those produced by metal industries, tanneries, and wet flue gas cleaning systems may affect their treatment by denitrification. Salt inhibition of denitrification has been reported, while impacts of individual ions remain poorly understood whilst being relevant for wastewaters where often the concentration of a single ion rather than the salts varies. The aim of this study was to determine the inhibition by inorganic ions (Na, Cl, SO and K) commonly present in saline wastewaters on denitrification and reveal its potential for the treatment of such waste streams, like those produced by NO-SO removal scrubbers.

Hydrochar and hydrochar co-compost from OFMSW digestate for soil application: 2. agro-environmental properties.

The work concerns the study of the hydrochar from digestate and hydrochar co-compost characterization as amendments. The processes for hydrochar and co-compost production were described in Part 1 of this work (Scrinzi et al., 2022).

Hydrochar and hydrochar co-compost from OFMSW digestate for soil application: 1. production and chemical characterization.

The best available technique (BAT) for managing the organic fraction of municipal solid waste (OFMSW) is represented by anaerobic digestion (AD) and subsequent composting. This research explored a new industrial model in the framework of the C2Land international project, with the insertion of hydrothermal carbonization (HTC) as a post-treatment for OFMSW digestate. The reaction was set for 3 h at three different temperatures (180 ÷ 220 °C); the wet solid hydrochar obtained after filtration was then co-composted with greenery waste as a bulking agent and untreated OFMSW digestate in four different proportions in bench-scale bioreactors.

Valorization of cow manure via hydrothermal carbonization for phosphorus recovery and adsorbents for water treatment.

The increased quantities of manure being generated by livestock and their extensive agronomic use have raised concerns around run-off impacting soil and groundwater quality. Manure contains valuable nutrients (especially phosphorus) that are critical to agriculture, but when directly land-applied the run-off of such nutrients contributes to eutrophication of waterways. This study investigates the hydrothermal carbonization of cow manure at two industrially feasible process extremes: 190 °C, 1 h and 230 °C, 3 h, to concentrate and then recover phosphorus from the solid hydrochar via acid leaching and precipitation.

Anaerobic degradation of digestate based hydrothermal carbonization products in a continuous hybrid fixed bed anaerobic filter.

This study investigates the suitability of continuous hybrid fixed bed anaerobic filter reactor for treating sewage and agro-industrial digestate hydrothermal carbonization (HTC) products; hydrochar and HTC liquor (HTCL). The reactor was operated for 300 days under mesophilic conditions at different organic loading rates (OLR); maximum OLRs of 7.4 and 10 gCOD/L/d were reached while treating HTC liquor and slurry, respectively.

Coupling hydrothermal carbonization and anaerobic digestion for sewage digestate management: Influence of hydrothermal treatment time on dewaterability and bio-methane production.

Hydrothermal carbonization (HTC) technology is addressed in the framework of sewage digestate management. HTC converts digestate into a stabilized and sterilized solid (the hydrochar) and a liquor (HTCL) rich in organic carbon. This study aims to optimize the HTC operating parameters, namely the treatment time, in terms of hydrochar production, HTC slurry dewaterability, HTCL bio-methane yields in anaerobic digestion (AD), and process energy consumption.

Hydrothermal carbonization coupled with anaerobic digestion for the valorization of the organic fraction of municipal solid waste.

Hydrothermal carbonization (HTC) was evaluated as a promising treatment to enhance the biomethane potential during anaerobic digestion (AD) of the organic fraction of municipal solid waste (OFMSW). The OFMSW was carbonized at different conditions and HTC products were tested for biomethane potential into AD. Results proved that the use of HTC liquid and slurry into AD led to an increase in biomethane production up to 37% and 363%, respectively, compared to OFMSW.

A critical review of the current technologies in wastewater treatment plants by using hydrodynamic cavitation process: principles and applications.

In the last decade, hydrodynamic cavitation (HC) was increasingly used in the field of wastewater treatment. Due to its oxidative capability, HC was applied to treat aqueous effluents polluted by organic, toxic and bio-refractory contaminants, whereas its mechanical and chemical effects have allowed to disintegrate cells of microorganisms in biological applications. Due to their geometries, HC can be detected in some reactors, in which a variation of hydraulic parameters in the fluid such as flow pressure and flow velocity is induced.

How inoculation affects the development and the performances of microalgal-bacterial consortia treating real municipal wastewater.

To date, little is known about the start-up of photobioreactors and the progressive development of stable microalgal-bacterial consortia with a view to the full-scale treatment of real wastewater. Two photo-sequencing bioreactors, one inoculated with Chlorella vulgaris (RC) and one with the absence of inoculum (RW), were fed with real municipal wastewater and run in parallel for 101 days. The influence of the inoculation was evaluated in terms of pollutant removal efficiency, excess sludge production, solids settleability and microbial community characteristics.

How suspended solids concentration affects nitrification rate in microalgal-bacterial photobioreactors without external aeration.

The use of microalgae for the treatment of municipal wastewater makes possible to supply oxygen and save energy, but must be coupled with bacterial nitrification to obtain nitrogen removal efficiency above 90%. This paper explores how the concentration of Total Suspended Solids (TSS, from 0.2 to 3.

Remediation of Soil Polluted by Organic Compounds Through Chemical Oxidation and Phytoremediation Combined with DCT.

Soils contaminated with organic substances is an important issue across Europe: In some areas, these are the main causes of pollution, or the second after contamination from waste disposal. This paper included an experimental application that compared three methods of remediation of contaminated sites, based on electric fields: A single treatment (electroremediation); and two combined treatments, phyto-electrochemical and electrooxidation (a combination of chemical treatment and a DCT-direct current technology). The contaminated soil was taken from a former industrial area devoted to oil refining, located between two roads: The one national and the other one for industrial use.

Effects of hydrodynamic cavitation, low-level thermal and low-level alkaline pre-treatments on sludge solubilisation.

WAS is a polluting and hazardous waste generated in WWTPs that must be treated to prevent pollution and human health risks. Anaerobic digestion is the most used process for sludge stabilization. However, it must be improved in terms of both speed and extend of degradation.

Optimisation of Fe/HO ratio in Fenton process to increase dewaterability and solubilisation of sludge.

Fenton is one of the advanced oxidation processes that can oxide organic compounds efficiently increasing the dewaterability of sludge. This study reports the optimisation of two reagents, Fe and HO, involved in the Fenton process in order to increase sludge dewaterability and solubilisation, which were evaluated in terms of SRF, CST and DS. The study was divided into two sets of tests.

One stage olive mill waste streams valorisation via hydrothermal carbonisation.

An olive waste stream mixture, coming from a three phase-continuous centrifugation olive oil mill industry, with a typical wet basis mass composition of olive pulp 39 wt%, kernels 5 wt% and olive mill waste water 56 wt%, was subjected to hydrothermal carbonisation (HTC) at 180, 220 and 250 °C for a 3-hour residence time in a 2-litre stainless steel electrically heated batch reactor. The raw feedstock and corresponding hydrochars were characterised in terms of proximate and ultimate analyses, higher heating values and energy properties. Results showed an increase in carbonisation of samples with increasing HTC severity and an energy densification ratio up to 142% (at 250 °C).

Correction to: Strict anaerobic side-stream reactor: effect of the sludge interchange ratio on sludge reduction in a biological nutrient removal process.

The correct Fig. 1 is shown in this paper.

Strict anaerobic side-stream reactor: effect of the sludge interchange ratio on sludge reduction in a biological nutrient removal process.

In order to investigate the impact of the sludge interchange ratio (IR) on both the sludge reduction process and the carbon and nutrient removal efficiencies, an anaerobic side-stream reactor (ASSR) at 20 °C and - 400 mV was operated for 300 days coupled to a sequencing batch reactor (SBR) for urban wastewater treatment. It was found that a 100% interchange rate, corresponding to an anaerobic solid retention time (SRT) of 2.5 days, was the most suitable case in terms of sludge reduction and wastewater treatment process, achieving a 66% sludge reduction compared to a control system simulated as an SBR.

Anaerobic Digestion of Cattle Manure Influenced by Swirling Jet Induced Hydrodynamic Cavitation.

In this work, a modified swirling jet-induced cavitation has been employed for increasing anaerobic digestion efficiency of cattle manure. The hydrodynamic cavitation (HC) treatment improved the organic matter solubilization and the anaerobic biodegradability of cattle manure. The degree of disintegration increased by 5.

A swirling jet-induced cavitation to increase activated sludge solubilisation and aerobic sludge biodegradability.

In this work, a modified swirling jet induced hydrodynamic cavitation (HC) has been used for the pre-treatment of excess sludge. In order to both improve the HC treatment efficiencies and reduce the energy consumption, the effectiveness of the HC reactor on sludge disintegration and on aerobic biodegradability has been investigated at different operating conditions and parameters, such as temperature, inlet pressure, sludge total solid (TS) content and reactor geometry. The inlet pressure was related to the flow velocity and pressure drop.

Shift in microbial community structure of anaerobic side-stream reactor in response to changes to anaerobic solid retention time and sludge interchange ratio.

A laboratory scale nutrient removal activated sludge system coupled with an anaerobic side-stream reactor was operated for 300 days treating real urban wastewater. A significant decrease in sludge production was obtained increasing the anaerobic solid retention time (SRT) and decreasing the sludge interchange ratio (IR). In this study, the microbial community structure was analyzed and compared with the sludge reduction performance.

Stoichiometric evaluation of partial nitritation, anammox and denitrification processes in a sequencing batch reactor and interpretation of online monitoring parameters.

A laboratory-scale sequencing batch reactor (SBR) performing partial nitritation - anammox and denitrification was used to treat anaerobic digester effluents. The SBR cycle consisted of a short mixing filling phase followed by oxic and anoxic reaction phases. Working at 25 °C, an ammonium conversion efficiency of 96.

Decolourization of Rhodamine B: A swirling jet-induced cavitation combined with NaOCl.

A hydrodynamic cavitation reactor (Ecowirl) based on swirling jet-induced cavitation has been used in order to allow the degradation of a waste dye aqueous solution (Rhodamine B, RhB). Cavitation generated by Ecowirl reactor was directly compared with cavitation generated by using multiple hole orifice plates. The effects of operating conditions and parameters such as pressure, pH of dye solution, initial concentration of RhB and geometry of the cavitating devices on the degradation rate of RhB were discussed.