Biochar as Alternative Material for Heavy Metal Adsorption from Groundwaters: Lab-Scale (Column) Experiment Review.

The purpose of this manuscript is to present a review of laboratory experiments (including methodology and results) that use biochar, a specific carbon obtained by a pyrolysis process from different feedstocks, as an alternative material for heavy metal adsorption from groundwater. In recent years, many studies have been conducted regarding the application of innovative materials to water decontamination to develop a more sustainable approach to remediation processes. The use of biochar for groundwater remediation has particularly attracted the interest of researchers because it permits the reuse of materials that would be otherwise disposed of, in accordance with circular economy, and reduces the generation of greenhouse gases if compared to the use of virgin materials.

Modification of natural zeolite clinoptilolite and ITS application in the adsorption of herbicides.

The clinoptilolite natural zeolites (NZs) posses low herbicide adsorption capacity demanding acid-, alkali-, or salt chemical modifications that enhance its adsorption. However, this may affect the material structure and charge distribution. Alternatively, zeolites may be synthesized at a high cost and time-consuming process.

Synthesis of a biobased resin and its screening as an alternative adsorbent for organic and inorganic micropollutant removal.

The sol-gel route was used to synthesize a biophenolic resin from a blend of Kraft black liquor and condensed tannin. The biobased resin has an amorphous structure and diversified surface functional groups. The biomaterial thermal stability was improved by Kraft black liquor, which increased the fixed carbon yield by 19.

The Sensitivity of a Specific Denitrification Rate under the Dissolved Oxygen Pressure.

The biological denitrification process is extensively discussed in scientific literature. The process requires anoxic conditions, but the influence of residual dissolved oxygen () on the efficiency is not yet adequately documented. The present research aims to fill this gap by highlighting the effects of on the specific denitrification rate () and consequently on the efficiency of the process.

Evaluation of automotive shredder residues (ASR) landfill behavior through lysimetric and traditional leaching tests.

With regards to European waste catalog, automotive shredder residues (ASR) can be classified both as a hazardous or non-hazardous waste according to its hazardous properties (H1-H14). It is thus important to carry out an adequate chemical-physical characterization to identify the presence and concentration of those substances able to give, to this extremely heterogeneous material, the hazardousness character of. The issue of waste characterization, to identify the proper site for appropriate waste disposal, is based, according to the relevant laws, to the use of leaching tests.

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.

Experimental and numerical evaluation of Groundwater Circulation Wells as a remediation technology for persistent, low permeability contaminant source zones.

Contaminants removal stoked inside low permeability zones of aquifers is one of the most important challenge of groundwater remediation process today. Low permeability layers can be considered persistent secondary sources of contamination because they release pollutants by molecular diffusion after primary source of contamination is reduced, causing long plum tails (Back-Diffusion). In this study, the Groundwater Circulation Well (GCW) system was investigated as an alternative remediation technology to the low efficient traditional pumping technologies to restore contaminated low permeability layers of aquifers.

Life Cycle Assessment of waste disposal from olive oil production: Anaerobic digestion and conventional disposal on soil.

Extra virgin olive-oil (EVO) production is an important economic activity for several countries, especially in the Mediterranean area such as Spain, Italy, Greece and Tunisia. The two major by-products from olive oil production, solid-liquid Olive Pomace (OP) and the Olive Mill Waste Waters (OMWW), are still mainly disposed on soil, in spite of the existence of legislation which already limits this practice. The present study compares the environmental impacts associated with two different scenarios for the management of waste from olive oil production through a comparative Life Cycle Assessment (LCA).

An empirical model for the evaluation of the dissolution rate from a DNAPL-contaminated area.

This paper investigates dynamic variation in the morphologic distribution of dense non-aqueous phase liquids (DNAPLs), which take into account the coupled mass transfer. Experiments were carried out in a 2D tank representing a reconstructed aquifer model. DNAPL dissolution rates were investigated over a wide range of DNAPL saturations, several source configurations, and different hydraulic conditions.

Contaminant back-diffusion from low-permeability layers as affected by groundwater velocity: A laboratory investigation by box model and image analysis.

Low-permeability lenses represent potential sources of long-term release when filled from contaminant solute through direct contact with dissolved plumes. The redistribution of contaminant from low to high permeability aquifer zones (Back-Diffusion) was studied. Redistribution causes a long plume tail, commonly regarded as one of the main obstacles to effective groundwater remediation.

Pore-scale simulations of concentration tails in heterogeneous porous media.

The retention of contaminants in the finest and less-conductive regions of natural aquifer is known to strongly affect the decontamination of polluted aquifers. In fact, contaminant transfer from low to high mobility regions at the back end of a contaminant plume (i.e.

Predictive model of limestone scaling in ammonia stripping towers and its experimental validation on a treatment plant fed by MSW leachate-polluted groundwater.

Groundwater pollution by municipal solid waste (MSW) landfill leachate is a global concern. Stripping towers are one of the most implemented techniques for the removal of ammonia pollution. This study presents a predictive computational model to estimate calcium carbonate precipitation in ammonia stripping towers.

Image analysis procedure for studying Back-Diffusion phenomena from low-permeability layers in laboratory tests.

In this study, the long-term tailing derived from the storage process of contaminants in low-permeability zones is investigated. The release from these areas in the groundwater can be considered a long-term source that often undermines remediation efforts. An Image Analysis technique is used to analyze the process and evaluate the concentrations of a tracer at different points of the test section.

The modelling of odour dispersion as a support tool for the improvements of high odours impact plants.

Two scenarios in terms of odour impact assessment were studied during the phase of upgrading of an existing waste treatment plant: CALPUFF was used for the simulation of odour dispersion. Olfactometric measures, carried out over different periods and different positions in the plant, were used for model calibration. Results from simulations were reported in terms of statistics of odour concentrations and isopleths maps of the 98th percentile of the hourly peak concentrations, as requested from the European legislation and standards.

Airborne toluene removal for minimizing occupational health exposure by means of a trickle-bed biofilter.

The paper presents the experimental results on a biotrickling pilot plant, with a water scrubber as pre-treatment, finalized to the treatment of an airborne toluene stream in a working place. The air stream was characterized by a very high variability of the inlet concentrations of toluene (range: 4.35-68.

Influence of denitrification reactor retention time distribution (RTD) on dissolved oxygen control and nitrogen removal efficiency.

Low concentrations of dissolved oxygen (DO) are usually found in biological anoxic pre-denitrification reactors, causing a reduction in nitrogen removal efficiency. Therefore, the reduction of DO in such reactors is fundamental for achieving good nutrient removal. The article shows the results of an experimental study carried out to evaluate the effect of the anoxic reactor hydrodynamic model on both residual DO concentration and nitrogen removal efficiency.

Experimental treatment of a refinery waste air stream, for BTEX removal, by water scrubbing and biotrickling on a bed of Mitilus edulis shells.

The paper presents the results of a two-stage pilot plant for the removal of benzene, toluene, ethylbenzene and xylene (BTEX) from a waste air stream of a refinery wastewater treatment plant (WWTP). The pilot plant consisted of a water scrubber followed by a biotrickling filter (BTF). The exhausted air was drawn from the main works of the WWTP in order to prevent the free migration to the atmosphere of these volatile hazardous contaminants.

Automotive shredder residue: a survey of the hazardous organic micro-pollutants spectrum in landfill biogas.

In this study, we report an extensive set of analytical results on the quality of the biogas produced by a landfill of automotive shredder residues. In particular, the investigation was directed towards the identification of a spectrum of polycyclic aromatic hydrocarbons (16 compounds) and a wide range of volatile organic compounds (35 compounds). This article highlights the most important indications of toxicological concern for the detected compounds.

Calculating specific denitrification rates in pre-denitrification by assessing the influence of dissolved oxygen, sludge loading and mixed-liquor recycle.

This article presents the results of an experimental study on the correlation among the specific denitrification rate (SDNR), the dissolved oxygen concentration (DO), the F:M ratio (F:M) and the mixed-liquor (ML) recycle in the pre-denitrification reactors fed by domestic sewage. The experimental curves reveal a 28.8-32.

Full scale treatment of ASR wastes in a modified rotary kiln.

A plant, designed for the thermo-valorisation of tyres, was specifically modified in order to treat Automobile Shredder Residue (ASR). Results from two full-scale combustion experiments, carried out on large ASR feeding lots (thousands of tons) indicate the proposed technology as a potential route to help the fulfilling of impending 95% reuse and recovery target set by the End of life Vehicle (ELV) Directive (January 2015). The paper describes the main operational troubleshot occurred during the first experiment (emissions at the stack out of regulatory limits and problems of clogging on the conveyer belt) and the consequent upgrading solutions (pre-treatment, introduction of waste double low-flow screw feeder and a cyclone prior to the main fan, modification of rotatory kiln inlet) adopted to allow, during the second long-term experiment, a continuous basis operation of the plant in full compliance with the discharge limit to the atmosphere.

Review of Italian experience on automotive shredder residue characterization and management.

Automotive Shredder Residue (ASR) is a special waste that can be classified as either hazardous or non hazardous depending on the amount of hazardous substances and on the features of leachate gathered from EN12457/2 test. However both the strict regulation concerning landfills and the EU targets related to End-of-Life Vehicles (ELVs) recovery and recycling rate to achieve by 2015 (Directive 2000/53/EC), will limit current landfilling practice and will impose an increased efficiency of ELVs valorization. The present paper considers ELVs context in Italy, taking into account ASRs physical-chemical features and current processing practice, focusing on the enhancement of secondary materials recovery.

On the ASR and ASR thermal residues characterization of full scale treatment plant.

In order to obtain 85% recycling, several procedures on Automotive Shredder Residue (ASR) could be implemented, such as advanced metal and polymer recovery, mechanical recycling, pyrolysis, the direct use of ASR in the cement industry, and/or the direct use of ASR as a secondary raw material. However, many of these recovery options appear to be limited, due to the possible low acceptability of ASR based products on the market. The recovery of bottom ash and slag after an ASR thermal treatment is an option that is not usually considered in most countries (e.

Use of a reactive transport model to describe reductive dechlorination (RD) as a remediation design tool: application at a CAH-contaminated site.

In this paper, a numerical model is presented that is capable of describing the complex set of biochemical processes that occur in chlorinated aliphatic hydrocarbon (CAH)-contaminated groundwater when an exogenous electron donor is added. The reactive pattern is based on the degradation pathways of both chlorinated ethanes and ethenes, and it includes electron donor production (H2 and acetate) from the fermentation of an organic substrate as well as rate-limiting processes related to electron acceptor competition. Coupling of the kinetic model to a convection-dispersion module is described.

Development and calibration of a model for biohydrogen production from organic waste.

Existing models for H2 production are capable of predicting digester failure caused by a specific disturbance. However, they are based on studies using simple sugars, while it is known that H2 production and fermentation kinetics vary with the composition and characteristics of the substrate used. Because the behaviour of biological processes may differ significantly when the digesting material is a complex matrix, such as organic waste, the aim of this study was to develop and calibrate a mathematical model for the prediction of hydrogen production on the basis of the results obtained from a laboratory scale experimental study using source-selected organic waste.

An integrated wastewater treatment system using a BAS reactor with biomass attached to tubular supports.

This paper describes laboratory experiments aimed to develop a new wastewater treatment system as an alternative to a conventional domestic wastewater plant. A modified Biofilm Airlift Suspension reactor (BAS), with biomass attached to tubular supports, is proposed to address low organic loads (typical of domestic sewage) and low residence time (typical of compact reactors technology). Attached and suspended biomasses, coupled to the high dissolved oxygen (DO), allow high removal efficiencies (90% and 56% for COD and N-NH(4)(+) removal respectively) and high effluent quality to be reached.