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Utilization of Biomanures in the Bioremediation of soil

Prof. I.Arkhipchenko*, Dr. I.Barbolina*, Dr. N.Zolnikova**

*All-Russia Research Institute for Agricultural Microbiology, Podbelsky Shosse 3, St.Petersburg-Pushkin 8, 189620, Russia

**Technology University, Moskovsky pr. 22, 198013, St.Petersburg, Russia

Development of modern civilization to a great extent depends on the state of environment. Despite the evidence of this fact the technocratic transformations in the society are always considerably ahead of the environment protection measures. One of the most important aspects of the pollution problem is losses of agricultural resources caused by degradation of soils, their erosion, inadequate application of mineral fertilizers.

With the use of modern monitoring and biological recultivation systems it is possible to restore the soil fertility and revive the soils for an agricultural rotation. The most promising way, in our opinion, is application of novel types of microbial pelleted biofertilizers produced from the animal breeding wastes.

The peculiarity of microbial fertilizers is an all-round action - they have the positive properties of the mineral ones (known chemical composition, a low application dose, absence of weed seeds, simple application procedure) and those organic (increase in the yield of agricultural crops by 70-80%, remediation of soil, promotion of its fertility, stimulation of the plant growth, 2-3 year long action, suppression of microflora causing diseases).

We have developed the process for production of the novel biofertilizer "Bamil" which is obtained from the microflora grown on the pigfarm waste waters [1]. An aerobic fermentation of the liquid pig manure makes it possible not only to obtain a purified waste water suitable for being discharged into open basins but also to produce a microbial biomass which serves as a basis for producing a microbial biofertilizer.

A know-how of our technology is in establishing special conditions for cultivating the microorganisms. These conditions enable us to obtain a microbial association with an increased content of nitrogen (8-9%) and phosphorus (3.5-4%). Prevailing in the association are nocardio- and corynebacteria of the genera Rhodococcus, Arthrobacter, Auroebacterium, Mycobacterium and the gram-negative of the genera Alcaligenes, Pseudomonas the majority of which promote the plant growth.

The microbial biomass is mixed (1:1) with the sludge of the primary settlers, then the mixture is transferred into the centrifuge where the moisture content is decreased from 97 down to 80%. Further, the mixture moves to the granulator and then to the drier. The end product having a 10-15% moisture content is packed into bags 20 kg in each. A passport, technical specifications for the production process, a hygienic certificate have been developed for the biofertilizer. The certificate for Bamil has been issued in Sweden which makes it possible to hold industrial tests.

By chemical parameters Bamil differs from other organic fertilizers by a high content (%) of nitrogen (5), phosphorus (1.8), potassium (0.8), calcium (3.4), magnesium (0.5), zinc (0.05), iron (1), manganese (0.8), copper (0.05), sulphur (0.5) and by the absence of nickel, mercury, cobalt, lead, cadmium and other heavy metals.

In our work we have studied the possibility for applying the biofertilizer Bamil both for recultivation of an anthropogenic soil as well as for degradation of pollutions with oil.

Objects and investigation methods

The object under investigation was the organic fertilizer "Bamil" made of the products of aerobic treatment of the pig-farm waste waters (Scientific & Technological Centre "NIKA", St.Petersburg, Russia). The experiments on application of this biofetilizer were conducted on the basis of Research Institute of Crop Production (Prague - Chomutov, Czechia).

The following substrates were used in the experiment: the soil degraded by the acid rains, clean material cut from the brown coal mining site, clean ash from the dumping place near a power station and their combinations. The fertilizer was applied to the 5 kg volume vessels containing the soil to make a 700 mg/kg nitrogen content. The grown crop was a perennial ryegrass (Lolium perenne L.). The soil samples to be examined were taken after a month and three months after planting the crops.

For determining the microorganism biomass a method of substrate-induced-respiration was used [2]. The ability of Bamil microflora to destroy the oil products and the degree of oil degradation were studied on a liquid mineral medium containing 1% of the oil products. The concentration of Bamil constituted 1, 3, 5%. Bamil-free variants served as a control. Count of the oil oxidizing microorganisms of the biofertilizer Bamil was conducted on a solid mineral medium where the sole source of carbon were the oil products introduced in the amount of 0.1 - 1 - 2%.

The degree of the oil destruction was determined by a fluorescent method using an appliance "Hitachi-65060". The oil was extracted using a hexon. The synchronous fluorescence spectra were registered at A l 60 nM.

The degree of the oil biodestruction was calculated by the formula:

control

where	- maximal intensity in the fluorescence spectrum of the tested sample,
	- maximal intensity in the fluorescence spectrum of the control sample;

Results and their discussion

Evaluation of Bamil application for the soil recultivation was done jointly with Research Institute of Crop Production (Prague) in the industrial region of North-Eastern Czechia which is the most anthropogenically contaminated area in middle Europe due to an intensive brown coal mining yielding an increased content of ash (20-40%), sulphur and a number of other harmful substances. In low regions where the coal mining takes place the soil is disturbed by a surface excavation and its burning at thermal power stations. The excavation from earth cuts after the upper layer of fertile soil is taken away leaves heavy clay containing 80 - 90% of sludge. These materials are characterized by low water-physical properties and low content of nutrient elements. Due to burning of low quality coal a great amount of ash is formed which covers and accumulates on the area of 2000 hectares. The ash is characterized by good water-physical properties although a low content of nutrient elements and by an almost absolute biological sterility. Such substrates are one of the most difficult objects for recultivation since they contain compounds toxic for plants, remain barren for a long time and are the sources of erosion and environment pollution.

Our research showed that application of the biofertilizer has considerably activized microbiological processes in the soil which is very important for restoring the microbocenoses, acceleration of the soil formation and enhancing the fertility of the reclaimed soils. Application of Bamil caused a 1--100 fold increase in the number of various groups of bacteria and fungi in the recultivated substrates. The biomass of the microorganisms in the fertilized variants was 3-8 times higher than in the substrates without the fertilizers. The maximal increase in the carbon of the microbial biomass was observed after application of Bamil in the ash variants. Addition of Bamil to the ash and to the mixture of the cut out ground ensured a 7.5-fold increase in the microbial biomass, the variant of the degraded soil-ash mixture after application of the

fertilizer yielded a 5.1-fold increase (Fig. 1).

Application of the biofertilizer Bamil ensured introduction of a great amount of basic nutrient elements for the plants and microorganisms into the anthropogenic soils. This revived the bacteriological activity of the soils and caused an intensive growth of the plants which leave a large number of the root leftovers. All this leads to an enhanced soil fertility and considerable acceleration of biological recultivation of the anthropogenic soils. Apart from that, the biofertilizer Bamil contains viable microorganisms represented basically by the bacteria of genus Bacillus which at the first stages of recultivation take an active part in the microbiological processes in the anthropogenic soils.

An increase in the biomass and in the amount of soil microorganism a similar variant where no fertilizer was used. The maximum yield was observed when Bamil was applied together with ash.

Thus, the microbial biofertilizer Bamil is an effective substrate in restoring the biological activity of the soil, it revives the disturbed soils and brings them back into agricultural use.

The study of the posibilities of applying this fertilizer for destroying the oil pollutions showed real prospects of putting the fertilizer application into practice on a wide scale. We have established that Bamil not only activizes the activity of the microorganisms oxidizing the oil in the soil but it is able to effectively degrade the oil pollutions on its own (Table 1).

Table 1 :

Effect of Bamil concentration on the degree of oil destruction

Even at 1% concentration of Bamil in the medium, a 53% destruction of the oil pollutions is observed, an increase in the Bamil phase enhanced the degree of destruction which is associated with a high activity of Bamil microflora. As we have established, the titer of the oil destroying microorganisms is 2 x 10⁴ colony forming units (CFU)/g of the fertilizer. The oil oxidizing microflora of Bamil includes the cultures of microorganisms capable as the only source of carbon and energy of utilizing various types of the oil pollution fractions including even the heaviest one - fuel oil (Table 2).

Table 2 :

Quantitative evaluation of Bamil microorganisms destructors of the

oil products at their growth on liquid and solid media

Thus, the obtained results showed that application of the microbial biofertilizer Bamil holds potential both for restoring the biological activity of the soil cenosis in the recultivation process as well as for degradation the oil containing pollutions in contaminated soils.

R E F E R E N C E S

Fig. 1. The effect of the fertilizer Bamil on the carbon content of microbial biomass (a) and on the yield of ryegrass (b) under recultivation of the soil.

1 - open cut; 2 - ash; 3 - open cut + ash; 4 - soil; 5 - soil + ash.

a

b

Résumé :

V tomto článku jsou popsány výsledky naší výzkumné práce, která byla zaměřena na zjištění možností zintenzivnění mikrobiální aktivity a degradace zaolejovanosti v různých substrátech po aplikaci organického hnojiva “Bamil”. Biohnojivo “Bamil” je složeno z mikroflóry získávané při aerobním čištění odpadních vod z prasečí farmy (přebytečný aktivovaný kal) a z primárního kalu z usazováků v poměru 1 : 1.

Aplikace Bamilu zajistila přísun velkého množství živin a mikroorganismů do antropogenních půd. To způsobilo zvýšenou bakteriální aktivitu půd, intenzivní růst rostlin a v konečném důsledku výrazně zlepšenou úrodnost rekultivované půdy. Nejlépe se rekultivační schopnost Bamilu projevila při jeho aplikaci s popelem.

Studium působení Bamilu při likvidaci zaolejovanosti prokázalo široké možnosti jeho aplikace v praxi. Zjistili jsme, že Bamil nejenom aktivuje činnost mikroorganismů oxidujících zaolejovanost v půdě, ale je také schopný degradovat zaolejovanost sám o sobě.