The identification, characterization and restoration of contaminated areas now represent a big environmental issue, both at European and national level. In the major industrialized countries the issue of contaminated land has come out in all its gravity in the late seventies when, against a widespread awakening of environmental consciousness, important pollutions events emerged. Consequently, in many European countries where the land is a limited resource, before brownfield degraded and sites and contaminated sites by illegal dumping, this represents a danger to the environment, besides being an economic damage.
In recent years, the increasing popularity of industrial activities due to product and services demand from the industrialized countries, on the one hand it has allowed the economic development, on the other has led to the pollution of the installations areas. Over time, therefore, the need for reducing emissions of existing and new plants has grown over, as well as the need to restore the physico-chemical conditions of polluted sites to the original. The law, therefore, is based on two paths: limiting the emissions and regulating the reclamation of polluted sites.
'As a private manufacturer of machinery and plants for environmental remediation, we believe it is essential to support today research and development for those technological innovations that will create concrete realities of tomorrow,' explains Pietro Baioni, CEO Baioni Crushing Plants. Innovation in processes and products, research, integration with local supply chains and universities: this is the path taken in recent years by Baioni to ennoble and preserve the 'made in Italy' from the threats of global markets.
Collaboration Baioni-Dicatech of Polytechnic of Bari was born out of a strong push for innovation to create a fruitful intertwining between science, technology, design and production with the aim at offering an effective instrument to the time and costs of reclamation, specially to make manageable and feasible the rehabilitation work in front of a technical and administrative rigidity of the country. 'And it is based on the synergy of different skills that we can now develop a comprehensive offer on the environmental issues with particular reference to pollution and soil protection and contaminated water' said Baioni.
Baioni Crushing Plants has already developed and built in Italy different types of systems targeted to the treatment and recovery of liquid and solid waste, the company is the only one in the national panorama to be engaged both on the design and manufacturing sides on soil and sludge treatment plants offering complete technology solutions. The company has full know-how and is able to ensure correct design of the line depending on the characteristics of the land to be reclaimed, as well as technological support and adequate training personnel. Last month two pilot plants were commissioned, being part of Lot 1 and Lot 2 of the tender issued by Dicatech which provided for the award of the supply and installation of equipment and science technology instrumentation provided for the expansion of the Laboratory of Chemistry and Technology for Environmental Protection, consisting of the Laboratory of Environmental Chemistry (LCA) and Environmental Technology (LTA) at the former Faculty of Engineering of the Polytechnic of Bari and the Taranto Pilot Technology Platform (PTP), located at the municipal sewage treatment plant in Taranto Bellavista. In particular, for Lot 1 a pilot inertization plant of sludge/soil/waste and for Lot 2 a pilot soil washing plant of sludge/contaminated land.
Description of the plants
Both pilot plants are made available from the Dicatech to improve specific skills and services with industrial partners, public and private bodies, through the exploitation and the use as testing ground on different types of sludge/soil/waste. Each plant has a production capacity of about 5 t/h and was designed and built both for inertisation (stabilization/solidification) of waste and for the remediation of contaminated soil. In particular the inertisation system Baioni aims to reduce the possibility of their dispersion and the danger of rejection. The stabilization/solidification treatment is used to treat dangerous and non-dangerous waste of any kind (liquids, sludge, mud, slime, solids, etc.), separately or mixed. The aim of the treatment is to modify (both “physically” and “chemically”) the substances included in the waste. The technique of soil washing instead consists of circulating pure or added water with organic solvents in the soil, surfactants, acid or basic, in order to desorb from the matrix a part of the pollutant so that it passes in solution or suspension. This technique consists in performing a real washing (washing) with water, aqueous solutions of surfactants or with organic solvents.
The process of soil washing
The material coming from the 'big bags' of approximately 2 m³ each is discharged into the hopper, then extracted by a belt conveyor and sent to a two deck screen equipped with 3 mm polyurethane panels: the material mixed with water is processed, the + 3mm is sent to storage, while the 0-3mm falls in the first half of the big tank. A first pump throws it to the first cyclone, placed above the attrition cell. The washed material is sent then to scrubbing (attrition cell), where it is mixed with chemical reagents; from here it is conveyed to the stabilization tank to be mixed with clean water. A second pump sends the material to the second cyclone, located above the screen, for the final treatment. The clean sand 0-3mm falls in the second half of the screen and is dehydrated, subsequently put to storage. The excess water conveyed to the stabilization tank is sent to treatment. The most relevant phases are:
- raw materials receiving
- separation from contaminating material
The inertization process
The inertization allows to reclassify the waste, it is possible to get a new non-contaminated inert material, no more dangerous for the environment, so transferable as secondary raw material or ready to for disposal or recovery. The treatment process Baioni designs is fully automatic, managed by a total control system of the plant; management and monitoring is carried out through electrical control panels with touch screen. The pilot plant is designed and built for mixing contaminated soil with the necessary chemical and physical reagents, designed to achieve stabilization-solidification of the waste.The most relevant phases are:
- raw materials receiving
- mixing of the materials
The heart of the system is represented by a reactor for stabilization/solidification, a mixer whose shaft and the blades have been sized to avoid any clogging of the material and to work at high temperatures. The set of 'additives', such as lime, cement, catalysts and sludge carbonate added to the material to be treated provides a large amount of energy in the exothermic reactions during the treatment of waste. The reactions are essentially produced by two chemical actions:
- Hydration reactions, such as for cement, calcium oxide and catalysts.
- Neutralization reactions, as in the case of carbonate sludge containing calcium hydroxide that react with waste at acid pH. Purposely manufactured for further study and to govern these reactions, this small experimental pilot plant can work on various types of mixtures. Both plants comply with health and safety regulations, UNI EN ISO 12100: 2010 par. 22.214.171.124 and UNI EN 14122 -1/2/3.
Final remarks and conclusions
The approach Baioni and the University of Bari are performing through the creation and management of the two pilot plants is completely new compared to similar plants operating on hazardous waste. The integrated management of the flows of materials and the quality of the end product is in fact the prerogative of the installations that produce raw materials or finished products but is, in fact, a novelty for installations dealing with the reduction of hazardous waste or of their recovery. The ultimate goal of the work will be the creation of an expert system that allows to obtain inert materials to be sent to landfill or to be recovered, with adequate quality and safety standards set by the European legislation and with costs in line with a sound business management.