Biochar application for marginal lands reclamation and primary/secondary agricultural residues processing 
1Kharytonov M.M., Klimkina I.I. 2, Frolova L.A.3, Rula I.V. 1,  Sova N.P. 1
1Dnipro State Agrarian and Economic University, Dnipro - 49600, Ukraine
E-mail: ecohous@ukr.net
2National Technical University "Dnipro Polytechnic", Dmytro Yavornytskiy Av. 19, Dnipro - 49005, Ukraine
3University of Chemical Technology, Prospect Gagarina, 9, Dnipro - 49005, Ukraine

The agri-food complex is one of the most important sectors of Ukrainian economy. Agricultural wastes and woody biomass are key components of renewable energy potential in Ukraine. Energy crops currently represent second part of the potential, since, except for several experimental plantations [1]. There are two major sources of the feedstock in agricultural forestry sector, which are primary, and secondary agricultural residues. Primary  agricultural  residues  are  those  materials  which  remain  in  fields  as  by - products  after  the  primary  product  of  crops  has  been  harvested.  These  include  different  materials  like  cereal  grain  straws,  of  wheat,  barley,  rice, etc., corn  stover (stalk and leaves), etc. Secondary agricultural residues are specific type of residues and include quite wide variety of biomass by - products of processing of agricultural products for food or feed production [2]. 
Food processing by - products represent a huge amount of waste resources that could be valorized for recovery of compounds both from energy and food points of view. The biomass pyrolysis is attractive because solid biomass and wastes can be readily converted into liquid products. Although the  primary  agricultural  residues  represent the largest share  of  the  technical  potential  (83 %), distribution  of  secondary agricultural  residues  are more equal and there are more options to process it using infrastructure of the facilities where agricultural feedstock is processed [3]. 
Ukraine  has  quite  a  big  potential  of  agricultural  residues which  mainly  consists  of straw  from  cereals and production residues  from  sunflower and maize  from  grain. At  present, less than 1 % of the primary agricultural residues potential is used  for energy purposes (combustion in  boilers, production of pellets and briquettes), mainly because of  undeveloped  infrastructure  and  logistics  system  for  the  feedstock  supply.  The   situation   with   secondary agricultural residues is   much   better   though   their   technical   potential   is in comparably lower than for primary. Over 77 % of sunflower husks biomass, for example, is directly burned in boiler systems, another 20 % is used for pellets production.  Almost all sunflower seed processing facilities have biomass boilers for utilization of sunflower husks. Agricultural residues from the waste streams of commercial processes have typically been considered to have very little inherent value, mainly constituting a disposal problem in the past. Most of the waste generated by sunflower and crop processing for bioenergy facilities are also confronted with the costs associated with collection and transportation in addition to the supply uncertainties in particular case. It is necessary also to provide better conditions to fast-growing species of the energy trees and crops cultivation in marginal lands. The high productivity of energetic plants plantations can be provided through the use of compost and sewage sludge as soil amendments. 
In modern terms it is necessary to develop new approaches in environmental strategy and tactics of agriforest management on the principles, which should provide as the rational nature use, protection and restoration. New strategies for environmental safety should be directed not to the development of individual, isolated nature protection measures, but towards a holistic, ecosystem-centered approach of environmental restoration. Pyrolysis is one of thermo-chemical processes, which convert the solid biomass in to liquid (bio-oil), gas, and biochar.
Biomass pyrolysis converts essentially 80–95% of the feed material into gases and bio-oil. Pyrolysis has been practiced for centuries for production of charcoal. This requires relatively slow reaction at very low temperatures to maximize solid yield. More recently, studies into the mechanisms of pyrolysis have suggested ways of substantially changing the proportions of the gas, liquid and solid products by changing the rate of heating, temperature and residence time [4]. There are few fundamental studies, experimental and theoretical, dealing with the biomass combustion and emission characteristics and physical and chemical properties of various biomass feed stocks. 
There are several studies made on development of reliable kinetic and thermos-transport models for investigation of biomass thermal conversion process. Although some certain adjustment to every type of feedstock and to every type of combined energy cycle is required. In light of existing situation in the alternative energy sector of Ukraine, it is important to obtain a better understanding of this technology and their potential for implementation and existing markets.  
The plants grown for biomass production are more prospects on marginal agricultural land where production is limited by poor soil properties. Fast growing crops can be planted in areas such as Prydneprovye, where large areas of reclaimed lands and marginal lands exist, where a suitable climate is present for biomass growth (miscanthus, swichgrass, poplar, acacia), and where the biomass can be transported to a large portion of the regional energy market. Second one is incorporation of low-cost agricultural residues burning technologies. Thus, Ukraine has good conditions for a significant expansion of biomass use both for energy purposes and biochar preparation. There are at two main ways for energy production: a) the production of pellets and briquettes to burn in boilers b) technological process of oxidative pyrolysis. Thus due to plant material gasification process we can obtain as gas as biochar. Biochar as soil amendment of additive to composts is known to be another solution improves plant water use efficiency thus it can be a powerfully simple tool to increase irrigation efficiency. Sustainable biochar is one of the few technologies that is relatively inexpensive, widely applicable, and quickly scalable. Biochar is a solid material obtained from the carbonization of biomass. Biochar may be added to soils or other materials with the intention to improve soil functions. We have got good results applying thermal treated poultry litter based biochar as organic fertilizer for grain crops. Biochar also has appreciable carbon sequestration value. Biochar is becoming much more commercialized, often sold with claims of reducing irrigation requirements by 50 percent. However, there is little solid research to back up many of these claims. Additionally, the effect of any soil amendment usually varies with soil type, and the particle size of the amendment.  As physical and structure properties of biosolids as composting material are quite important for the further land application, the origin of biosolids and the process.
The main objective of our work is the investigation and development of eco-innovative, cost effective and environmentally acceptable technologies, which will be applied on an industrial (large) scale, in order to see the large-scale products of the biochar and biosolid industry, to estimate biochar amendments application to polluted with some toxicants soils; to see prospects related with biochar application to waste water treatment, to evaluate and compare stand establishment of potential biofuel /bioproduct crops (miscanthus, switchgrass, hemp, flax, etc) growed in forest-steppe and steppe zones of Ukraine; to study novel phytostabilization and phytoremediation technologies based on biochar application. Special attention is paid in biochar  characterization as biosorbent [5]. Model experiment were managed with biochar as amendment to substrata of reclaimed minelands. Porous biochar obtained from pyrolised nutshell biomass was tested in the light-room experiments with sunflower, corn, sudan grass, sorghum, miscanthus and switchgrass. The objects under research were ordinary medium – loamy black soil and red - brown rock. Biochar was added to each substrate in 3%. Heavy metals uptake estimation and DTG analyses for each sample of biomass were made according to trials.

1.	Bielski. S. The agricultural production of biomass for energy purposes in Poland. Agriculture & Forestry- 2015 - Vol. 61, Issue 1- P.153-160
2.	Czernik S., Bridgwater A. V. Overview of application of biomass fast pyrolysis oil. Energy &Fules.-2004-18 -590p.
3.	Geletukha G., Zhelyezna T., Lakyda D., Vasylyshyn R., Zibtsev S., Lakyda I., Böttcher, H. Potential of biomass for energy in Ukraine. Kyiv. 2010- 27p.-web-address: http:// www.eu-bee.info
4.	Tilmann D.  The combustion of solid fuels. Academic Press, Boston. 2000.-199p.
5.	Kolodynska D., Krukowska J., Thomas P. Comparison of sorption and desorption studies of heavy metal ions from biochar and commercial active carbon. Chemical Engineering Journal 307. 2017 - P. 353-363