Complete Actions

The objectives of Action A1 were: (i) to provide a full characterization of materials with potential use as soil additives; (ii) to provide a preliminary characterization of degraded soils in mining areas in Portugal as well as the collection and characterization of samples to be used in Action A2; and (iii) to select specific types of bottom ash (BA) and fly ash (FA) samples as well as types of organic materials to be mixed and tested as soil additives in Action A2.

At the end of July 2016, all objectives of the action A1 were successfully accomplished. Expected results for this action were successfully attained, as summarized next.

Four ash sampling campaigns were conducted in the first six months of 2016 (January, April, May and June) in order to evaluate the seasonal variability of their properties as well as to assess the influence of type of residual forest biomass used as fuel in the pulp and paper industry. Ash from six specific origins was sampled separately. A thorough physico-chemical characterization of biomass ash materials was performed, including the analysis of: pH, moisture content, loss-on-ignition, particle size distribution, major and minor chemical elements, mineralogical analysis by X-ray diffraction, leachability and water soluble chemical elements.

The sludge from a secondary wastewater treatment process was sampled with the same periodicity of ashes from biomass combustion. A thorough physico-chemical characterization of these materials was performed and included analyses of parameters determined by Portuguese Decree-Law 276/2009 on the agricultural use of sewage sludge as well as additional parameters considered necessary in the scope of this project (pH, moisture content, total nitrogen, total phosphorous, major and minor chemical elements, organic contaminants - LAS, NPE, PAH, PCB, PCDD/F - and pathogenic microorganisms).

Two sampling campaigns were performed to collect a total of 122 mining soil samples, divided for the three study areas (Aljustrel – 39 samples; Lousal – 39 samples and São Domingos – 44 samples). A full characterization of the mining soils samples was performed. Soil analyses included: pH; electrical conductivity; loss-on ignition; total and organic carbon; texture; cation exchange capacity; water holding capacity; bulk density; total nitrogen and phosphorous; available phosphorous and potassium; mineralogical analysis; Aqua-regia digestion and analysis of As, Cu, Pb, Zn, Cd, Ni, Cr, Co, Ba, U, Fe, Mn, Al, Sb, Li, Be, Se, B and Mo; total Hg concentrations; extraction of potentially available elemental concentrations (using both 0.43 M HNO3 and 0.01 M CaCl2 extractions).

In this Action, materials previously selected in Action A1 (ashes and organic materials) were tested as soil additives. Methods for preparation, pre-treatment and mixing of materials were developed and optimized. Mesocosm tests (pot and column experiments) were performed to optimize application rates, necessary to achieve the following targets: to correct soil pH, to increase soil nutrient pools, to reduce availability of potentially toxic elements, to avoid salt stress for plants; to comply with the criteria from the ‘Sewage sludge Directive’ (86/278/EEC) and relevant Portuguese legislation Decree-Laws No. 276/2009 (sludge application to agriculture), No. 73/2011 (waste management) and No. 103/2015 (fertilizing materials). The effects of the soil additives on soil properties were quantified.

Action C.1 - Technical support – monitoring of soil properties and plant cover during the Pilot Project
Action C.2 - Technical support - field and laboratory testing of availability of contaminants to sensitive receptors and ecotoxicological risk assessment
Action C.3 - Technical support - monitoring of the impact of soil improvers on soil functions
Action C.4 - Monitoring of the socio-economic and environmental impact of project actions

Monitoring Actions (C.1, C.2, C.3, C.4) were all completed.

Major conclusions and outcomes from monitoring Actions were:
- All the three types of soil improvers (biomass ash granules; biomass ash granules + composted biological sludge; unstabilized mixture of biomass ash and biological sludge) developed and tested in the project allowed to restore the chemical and ecological quality of severely degraded mining soils suffering from extreme pollution with heavy metals, salinity and low pH;
- Long-term effects of the new soil improvers included: neutralization of soil acidity (from pH 3.3-4.5 to pH values in the range of 4.8-7.6); increase in soil total organic carbon (from 0.3-0.7% to 4% TOC); increase in the soil water holding capacity (from 0.3 to 0.6 L/kg); significant increase the fraction of available nutrients (namely Ca, K, Mg, P); significant decrease in lability of potentially toxic elements in soils (Al, Cd, Co, Cu, Mn, Ni, Pb and Zn);
- All the three types of soil improvers promoted plant growth in otherwise unvegetated soils; significantly increased soil microbial biomass and activity; and significantly improved survival and reproduction of soil organisms;
- The combined application of stabilized biomass ash granules + composted sludge exhibited the best balance between maximization of environmental and social-economic benefits and minimization of potential environmental risks among the three treatments tested (and when compared with commercial potential alternative solutions from the market).

Action B.1 - Pilot Project - Pilot scale application of soil additives at three mining sites
Action B.2 - Decision support system for the management of biomass combustion ashes and for EU-wide scale

Implementation Actions (B.1 and B.2) were completed in March 2021.
Major outcomes:

- Recovering of mining soils functioning was achieved with all new soil improvers tested

- Ash granules + compost showed to be best balance between benefits and potential risks
- The widespread adoption and use of these materials have the potential to spark changes in multiple areas, such as:
- Creation of a new business and new jobs. The business will focus on ash waste removal from energy production industrial plants, a service which in itself may be sold for profit and drive the business forward.
- Promotion of the environmental sustainability of energy production and of the pulp and paper industry sectors, notably through the reduction of waste landfill needs.
- The adoption of ash-based correctives can increase competition in the EU fertiliser market.

Action D.1 - Analysis of public awareness on the benefits and constraints of the application of industrial by-products in the recovery of degraded soils
Action D.2 - Communication and dissemination of project results to public and relevant stakeholders and networking with other LIFE and non-LIFE projects

Communication and Dissemination Actions (D.1 and D.2) were completed in March 2021, with the end of the project. Over 10,000 people have been informed about the project progress and results, through various meetings, technological events, conferences, workshops, and school activities which the project organized or participated in. The project team members have interacted with experts from more than 15 countries.

Action E.1 - Project management and monitoring of project progress
Action E.2 - After-LIFE Plan

Project Management and the After-LIFE Plan (E.1 and E.2) were completed in March 2021, with the end of the project.
The technical advances and the economic, social, and environmental viability study developed in this project, established that the developed ash-based materials have an interesting potential to be applied in large-scale recovery of degraded soil. There are thousands of hectares of soils in Portugal alone, for which this solution is feasible. One interesting option is the implementation of a centralized ash-processing plant, which allows managing biomass ash, and from there transport it for areas in need of recovery

Complete actions