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Management of residues from mining, charcoal and sewage meets agriculture, forestry and the interest of financial markets



Our proposal aims at addressing four major problems in waste management, agriculture and forestry:

  1. high volume of residues from mining, charcoal industry and sewage treatment companies, with little use and lots of problems for adequate disposal;
  2. high costs of chemical soil fertilization;
  3. lack of interest from land owners in soil conservation and reforestation, leading to severe exploitation and eventually degradation of their farms; and
  4. lack of availability of environmental-friendly investment products or opportunities in timber assets.

We propose to use residues from mining (rock powder), charcoal making (biochar) and sewage treatment (sewage sludge) to enhance soil fertility at unprecedented levels and at very low costs. This fertilizer will be used to implant forests of high value timber, such as teak (Tectona grandis), African mahogany (Khaya sp.), Ipe for excellent financial returns on the long term, integrated with crops and fruits, for short term returns and constant cash flow.

The main innovation of this project is the integration of different technologies and inputs already known and used in some agricultural activities, but in isolation. The differential is therefore the complementarity of the selected techniques that together will be able to respond to the main challenges of today: responsible waste management, high quality and efficient production, soil and water recovery, accessibility to small producers and investors, economic viability, social and environmental, and large capture of greenhouse gases.

The financial attractiveness of the opportunity will be tempting not only for land owners but also for investors of all sizes, especially small ones, to whom we intend to offer the product via crowdfunding platforms, with the use of risk pooling financial techniques.

We believe that our proposal will create a virtuous cycle that will boost the prospects of replication and scaling of the project.

Is this proposal for a practice or a project?


What actions do you propose?

In Brazil, where the project will be developed, the mining activity produces an enormous amount of rock powder, a residue that is a problem for most mining plants, but is an excellent fertilizer and soil conditioner.

The country also has a great deal of charcoal plants that produce charcoal powder (biochar) as a residue. Recent researches have demonstrated a number of benefits of using biochar for agricultural productivity and carbon sinking.

Sewage sludge is another problem that affects most cities in the country, whose utility for plant nutrition has been proven as long as some limits of contaminants are respected.


Based on this, we will select degraded lands close to mining, charcoal and sewage treatment plants and establish partnerships with land owners. Land owners will be attracted by the high expected returns. Differently from conventional partnerships that pay a monthly fee for the use of the land, we intend to share 15-25% of the short and long term returns with land owners. In addition, land owners would be highly interested in our project because it will allow them to recover the soil and the farm productivity with no disbursement.


We will also establish partnerships with mining, charcoal and sewage treatment companies so as to obtain rock powder, biochar and sewage sludge. We will combine them in appropriate proportions to and mix them into the soil in order to prepare it for the implantation of the forest and the other cultures, providing them with adequate nutrition and long term benefits with regard to water and carbon retention, Ph balancing and the proliferation of microorganisms in the soil. We expect to observe soil recovery right after the incorporation of the mixture.


Then, we can start plantation. The objective of the plantation is to continue soil recovery, enrich the soil by incorporating nitrogen and reduce/end the need to use chemicals. Plantation will follow the techniques of sintropic agriculture developed by Ernst Gotsch. It will be organized in lines and every line will be formed by different types of plants. We will alternate crops, fruits and high value timber trees. Plants will be selected according to the weather and terrain characteristics of the farm. It is worth noting that the planting of food will respect the time frame established in the norms of use of sewage sludge.


By designing the plantation system to be highly profitable, with returns in the short and long term and with low cost of inputs due to the low use of chemicals, we expect to reach a broad spectrum of investors and land owners. Investors are usually return driven. To attract a broad spectrum of investors, we design our project to be economically attractive. However, our main objective is to shift behaviour towards a new conscious form of investing that focus not only on returns but most importantly on the social impact of the investment. We want to allow individuals to invest in an environmentally-friendly project that aims at land and forestry recovery offering a good return at the same time. To achieve this we will invest in marketing and hire an IT firm to develop a crowdfunding platform.

Who will take these actions?

The authors will participate in the management of the company. They will be responsible for finding degraded areas to start the soil recovery and the plantation, funding to sponsor the project, costumers for the products and for hiring personnel.

We expect to find funding from three main sources:

1)     Individuals through crowdfunding. In Brazil it is not possible for individuals to invest in reforestation and recovery of degraded areas. The closest you could get is to invest in timberland funds that provide funding to reforestation projects. By designing the project to be economically sustainable with an attractive internal rate of return, we believe it is going to be a highly attractive investment for individuals. We have noticed a growing interest in investment products with such a profile, especially from Generation Y and Millenials, who will hold the economic power in 10 to 20 years time;

2)     Government: through loans with subsidized rates from governments;

3)     International Funds: funds focused on soil recovery or reforestation would be a great source of funding and one of the great actors involved in taking these actions.

We will establish a partnership with an IT firm to set up the crowdfunding platform.

Finally, technical assistance regarding personnel training and cultivation methods will be provided by a consultant firm with a respectable record in sustainable conduction of agricultural, livestock and forestry activities in Brazil.

Where will these actions be taken?

Actions will be taken in farms from 5 to 100 hectares (12 to 250 acres) throughout Brazil. We are looking for degraded areas typically used for pastures. We will focus our search on the most endangered biomes: the Amazon, the Cerrado (our Savanna) and the Atlantic Rainforest.

In the Amazon we will start the project in Para where we can easily find degraded areas and export timber to Europe. In the Cerrado we will start in Goias, a Brazilian state known for extensive livestock exploration. In the Atlantic Forest we will start in the mountain range of Rio de Janeiro where we can focus in sustainable production of organics and find land threatened by erosion. Tree and crop species will be chosen accordingly.

In those states we will concentrate our search in areas close to our inputs, namely: charcoal industry, sewage treatment stations and mining sites. Finding areas close to our inputs is paramount for the project to be economically sustainable.

In addition, specify the country or countries where these actions will be taken.


Country 2

No country selected

Country 3

No country selected

Country 4

No country selected

Country 5

No country selected


What impact will these actions have on greenhouse gas emissions and/or adapting to climate change?

Carbon capture is one of the pillars of our project. The main product of our activity will be hardwood timber from species that grow faster in our edaphic conditions (aprox. 25 years to the final cut), whose final destination is furniture, construction and other long-term uses. This way the carbon captured by our trees will not go back to the atmosphere, as does the timber used in the pulp and energy industries.

The estimated rate of CO2 capture is 0.14 tons per tree, in 20 years. So in one hectare, were we intend to plant 1.666 hardwood trees in a 25-year cycle, we expect to have in excess of 233 tons of CO2 captured from the atmosphere. References have been brought from the International Forest Alliance (

In addition, we intend to use the solution proposed by Dr. Thomas Goreau to reverse global climate change (see Geotherapy: innovative methods of soil fertility restoration, carbon sequestration, and reversing CO2 increase). The main idea is to use rock powder and biochar as a strategy for carbon sequestration. This is the cheaper and most efficient method to return the carbon from atmosphere to the soil.

So we will take rock powder from mining plants close to our area and incorporate it in the soil. In the same way, we will use charcoal powder from plants of charcoal, and sewage sludge from sewage treatment station to increase the amount of carbon in the system and fixate it into the soil in a stable way.

With this strategy we think that our project is strongly capable of dealing with global climate change as it captures carbon from the atmosphere in two different ways: planting hardwood trees and managing the waste of three different activities.

What are other key benefits?

Degraded land is one of the main drivers of deforestation in Brazil as people keep moving into the forests and bringing them down in search for better soils (i.e. not yet degraded). Our Initiative aims at rebuilding the fertility and ecological functions of areas that have been degraded along the years and are currently unproductive. As we restore degraded soils and improve their productivity the pressure for deforestation will likely lower in the Amazon rainforestand, the Atlantic Forest and the Cerrado (Brazilian savanna).

By integrating hardwood timber with food production in high fertility soils, our initiative will tackle the two main causes of deforestation in Brazil: demand for hardwood and agricultural production.

In addition, we aim at transforming the waste from three different activities in a magnificent fertilizer and soil conditioner. By combining rock powder, charcoal powder and sewage sludge we will not only dramatically reduce the production of greenhouse gases in those activities but also enhance the capacity of carbon capture in our reforestation and agricultural activities. In our view this is a perfect model to help Brazil perform its declared climate change goals: 43% reduction in greenhouse gas emissions until 2030. In this context, Brazil has committed itself to a four-action plan: to end illegal deforestation, to restore and reforest 12 million hectares (29.65m acres), to recover 15 million hectares (37m acres) of degraded pastures, and to implant 5 million hectares (12.3m acres) of integrated crop-livestock-forestry systems.

The main idea is to develop protocols to replicate this model across the country by establishing partnerships with land owners who need help to make their estates sustainable and profitable. Our model is bound to be of great assistance to a number of land owners who are currently non-compliant with Brazilian environmental laws, which require that rural properties maintain 20% to 80% of their areas with forests, where they can only practice sustainable harvesting.

We understand that we will be able to assist Brazil in meeting the goals in the abovementioned four proposed actions, with the difference of using residues that will potentiate our ability to capture carbon from the atmosphere and incorporate it into the soil.

In addition, our plantation method is labour intensive. Therefore we will hire and train a great number of people, thus tackling the high unemployment and low productivity Brazilian rates. By hiring a great number of employees we also expect to help developing the local economy.

Finally, we aim at shifting investment behaviour towards a new conscious form of investing that focus not only on financial returns but most importantly on the social and environmental impacts of the investment. We want to allow individuals to invest through crowdfunding in an environmentally-friendly project that aims at land and forestry recovery and offers an attractive return at the same time.


What are the proposal’s projected costs?

We can divide the production costs in two types:

1) Culture

Year 0 (implantation)

Input: 8800

Service: 4600

Administration: 3600

Total: 17000


Following years (year 1-25 - average per year)

Input: 1600

Service: 2900

Administration: 1000

Total: 5500


2. Soil improvement

Year 0 (implantation)

Sewage Sludge Freight: 100

Coal powder freight: 100

Rock powder freight: 100

Input: 50

Service: labor costs embedded in culture costs

Total: 350

Total costs per hectare: 17350 in year 0 and 5500 per year in years 1-25

Other costs would include certification of the wood and transportation of the lumber. The transportation costs of the lumber will be embedded in the selling price. Other products would be sold locally with very low additional costs.

Wood certification: 5500 per year in years 1-4

As the agriculture system is labor intensive, one of the challenges of the proposed actions is to find the appropriate employees, training them and retaining them for the duration of the project. The other main challenge is to form the right customer base that perceives value in our proposal and agrees to pay a fair price for the products.


The short-term impacts of our project will be:

- soil recovery, from the moment we start the project in an area, since this our first step;

- employment of residues from mining, charcoal and sewage treatment plants in the recovery of the soil;

- sustainable production of food, starting in about 6 months from the moment they are planted;  

- sustainable production of timber, mainly from thinnings made from years 10 to 12;

- helping the local economy through employment and training of people; and

- changes in the investment behaviour of Brazilians, by offering safe and attractive environmentally-friendly forest-based investment products.

In the medium-term we project:

- major reforestation of previously degraded lands;

- restoration of ecological processes in the regions;

- supply of high quality timber to the markets, thus lowering deforestation pressures;

- democratization of investments in sustainably grown forest assets;

- change in the behaviour of landowners and other crop and livestock producers towards practices that conserve the soil and integrate forests with their activities;

- beginning of changes in the social patterns of the regions where we work, with possible social ascension.

In the long-term, after successive cycles of incorporation of rock powder, biochar and sewage sludge, in addition to the production cycles of both food and fine wood, we expect the soil of our plots to have a structure and fertility similar to the Terra Preta de Indio (Indian Dark Earth), a man made soil found in the Amazon basin. As a consequence we will have a significant stock of carbon re-incorporated into the soil, as well as the huge reduction of carbon dioxide emissions for food and hardwood production compared to the mainstream production models. And depending on the scale we reach, we believe we will have contributed significantly to the preservation of our natural forests.

Our project will also have made a significant and permanent impact on people's behaviour towards investments and on the families of our employees, with real chances of social ascension through long-term wealth accumulation and furthering of education of subsequent generations.

About the author(s)

Fabiana Ladvocat Cintra Amaral Carvalho – Fabiana is an engineer with a master in Finance. Fabiana lives in Rio de Janeiro, Brazil, and works with banking regulation. She has contributed to the project by helping to build it economically attractive. She helps to highlight the project risks and suggests improvements to mitigate them. Finally, she is contributing to finding funding to the project, especially through crowdfunding.

Danilo Takasaki Carvalho – Danilo is a has a degree in Law with an LLM in Banking Law and Regulation of Financial Markets. He lives in Rio de Janeiro, Brazil. He has been studying and dedicating himself to sustainable development issues since his undergraduate studies and has currently been researching ways of designing the business model that can speed up the replication of the project throughout the country. His contributions to the project will be mainly on the strategic management and legal/compliance areas.

Rafael Cavalcante Ajuz – Rafael is a biologist with a masters degree in animal biology. Lives in Brasilia, Brazil, and works with environmental impact analysis of major energy infrastructure projects in Brazil. Has been studying new technologies on recovery of degraded areas and reforestation. His contribution to the project will lay on the technical and operational aspects.

Cristiane Ajuz – Cristiane is a lawyer specialized in Public and Private Law. She lives in Brasilia, Brazil, and will contribute to the project in the legal aspects of contractual and corporate issues.

Related Proposals

Several Climate CoLab proposal relate to ours. From the time of publishing, we found these:


Goreau, Thomas J., Larson, Ronal W., Campe, Joanna. Geotherapy: Innovative Methods of Soil Fertility Restoration, Carbon Sequestration, and Reversing CO2 Increase. CRC Press, 2014.

Simon Jeffery, Diego Abalos, Marija Prodana, Ana Catarina Bastos, Jan Willem van Groenigen, Bruce A Hungate, Frank Verheijen. Biochar boosts tropical but not temperate crop yields. Environmental Research Letters, 2017; 12 (5): 053001 DOI: 10.1088/1748-9326/aa67bd

On Syntropic farming, see:

Götsch, Ernst. O Renascer da Agricultura. Trad. Patricia Vaz. 2nd. ed. Rio de Janeiro: AS-PTA, 1996. Available at: