SUMMARY.


Environmental sustainability is one of the goals of the Colombian coffee growing, and to obtain it the National Federation of Coffee Growers of Colombia counts with National Coffee Research Center (Cenicafé) for generation of knowledge and technologies that contribute environmentally to the development of sustainable production systems and Extension Service to facilitate that the knowledge and the generated technologies arrive to the coffee growers and get implement by them.

For wastewaters treatment generated in washing stage, during the process of humid benefit of the coffee, denominated “honeyswaters” and which displays acid pH and COD concentrations near at 27000 ppm, Cenicafé developed modular, economic, and efficient systems of anaerobic treatment, that don’t need addition of neutralizing and which allow to eliminate near 90% of the organic contamination that enters to such.

Nevertheless, the effluents of anaerobic systems still conserve high organic loading (COD between 2000 and 3000 ppm), which generates negative ecological impacts when they are disposal in water bodies of the Colombian coffee zone, being necessary to implement economic systems of post-treatment and easy adoption on the part of the coffee growers, with capacity to reduce organic loading of the effluents to values below 490 and 279 ppm, in terms of COD and BOD5, respectively (corresponding to the concentration lethal average found for the fish Lebistes reticulatus, more sensible bioindicator aquatic in studies of biological impact made in the zone of study) and this way diminish its ecological impact.

The main objective of this investigation is generation of necessary information for the design of integrated biosystem that uses aquatic macrophytes for post-treatment of coffee honeyswaters with the purpose of their effluents generate the smallest possible negative impact on coffee aquatic ecosystem, presenting viable alternatives, from a technical, economic, environmental and social point of view, for suitable disposal of the generated biomass during purification process.

In a first test, that consisted of 18 treatments and lasted of 209 days, the effect of the concentration, in terms of COD, of effluents of anaerobic systems on the performance of aquatic treatment systems, was determined on scale of mesocosm, using waterproofed ponds of 2,0 m of length * 0,5 m of width * 0,5 m of effective depth, seeding with the floating species Eichhornia crassipes, Pistia stratiotes, Salvinia auriculata and with the emergent species Typha angustifolia, evaluating the removal of the parameters physical-chemistries COD, BOD5, TS, TSS, NT, PT, K, S and of the group of Coliforms bacteria.


The aquatic treatment systems were evaluated under three concentrations of influent (undiluting and diluted to 40 and 10% with faucet water) to an inflow rate of 70 ml/min (Q1). Additionally, two control experimental systems that weren’t planted were used as controls, one for floating species and another for emergent species, with the purpose of determining real effect of the species in the removal of parameters microbiological and physical-chemistries established.

The obtained regression equations allows to predict that inhibition in the growth of E. crassipes, P. stratiotes, S. auriculata and in the increase of the number of plants of T. angustifolia appears to COD concentrations, in effluent of anaerobic systems, of 1281, 1222, 903 and 508 ppm, respectively.

First-order kinetic equations allowed describing the elimination of COD, BOD5, TSS, NT, PT and K in the aquatic treatment systems fed with effluents of anaerobic systems used on the treatment of coffee wastewaters.

There weren’t found statistical differences to 5% in removal of COD and BOD5 between the 4 aquatic species and the control of the emergent species, but it was in removal of nutrients (N, P, K) between the ponds with aquatic macrophytes and their control. Considering rates of growth of the macrophytes and their rate of elimination of BOD5, TSS, NT, PT and K, the performance it was E. crassipes > P. stratiotes > S. auriculata > T. angustifolia.

In a second test, that consisted of 24 treatments and lasted of 146 days, the effect of the organic loading of effluents of anaerobic systems on the performance of aquatic treatment systems was determined using the same ponds, species of plants and determining such parameters of removal evaluated in test 1. The aquatic treatment systems were fed the same concentrations of influent evaluated in test 1 and two inflow rate: 105 ml/min (1,5Q1) and 140 ml/min (2Q1).

The obtained regression equations allows to predict that inhibition in the growth of E. crassipes, P. stratiotes, S. auriculata and in the increase of the number of plants of T. angustifolia appears with organic loading applied average of 926, 739, 443 and 825 kg BOD5/ha-day, respectively.

Considering the performance of the 4 aquatic species in removal of parameters BOD5, TSS, NT, PT and K (measured as mg/m2-d) in the 2 evaluated tests, determined that the best species for the post-treatment of coffee watershoneys it was E. crassipes, followed of P. stratiotes, T. angustifolia and S. auriculata.

In a third test, lasted of 393 days, the effect of monoculture versus combination of species was evaluated in aquatic treatment systems for post-treatment of coffee honeyswaters, using a monoculture of floating species E. crassipes (selected like the best in two previous tests), a mixture of floating species E. crassipes, P. stratiotes and S. auriculata and a polyculture using, in its order, E. crassipes, P. stratiotes, T. angustifolia and S. auriculata. Each treatment system was constituted by 4 ponds of 500 liters, each one, arranged in series and fed an inflow rate of 105 ml/min.

They weren’t found statistical differences to 5% in elimination of parameters BOD5, TSS, NT, PT and K between the three aquatic treatment systems. Considering removal of parameters physical-chemistries evaluated (measured as mg/m2-d) it was that the aquatic treatment system that it contained species E. crassipes, P. stratiotes, T. angustifolia and S. auriculata showed a better performance than the system that operated with the mixture of 3 floating species (E. crassipes, P. stratiotes and S. auriculata) that presented a better performance than the system that used only species E. crassipes.

The obtained regression equations, incorporating the new generated data, allowed to fit the values of prediction for E. crassipes, obtaining that to concentrations of COD of 1172 ppm (n = 27, R2 = 0,65), equivalent to 562 ppm as BOD5 (n = 27, R2 = 0,64) and organic loading applied average of 785 kg BOD5/ha-day (n = 27, R2 = 0,69) appears inhibition of its growth.

In a fourth test, mounted parallel with first test and based on obtained results on small-scale (microcosm), it was validated on scale coffee farm, during 3 years, an aquatic treatment system with floating species E. crassipes and P. stratiotes connection in series to a modular system of anaerobic treatment of coffee honeyswaters, using 3 waterproofed lagoons of 6,0 m of length * 1,5 m of width* 0,5 m of effective depth, operate an inflow rate of 550 ml/min, for a coffee farm with an average production of 844 @ cps/year and a generation average of coffee wastewater of 5 liters/kg cps. The aquatic treatment system allowed diminishing average concentration of COD and BOD5 of honeyswaters anaerobically treated from values of 1902 and 821 ppm to values of 328 and 143 ppm, respectively, with a hydraulic residence time of 16 days.

The effluents of the aquatic treatment system were conducted to a small lagoon of 60 m3 used in fish farming with the species red Tilapia, without being observed poisonous effects on the animals, which is constituted in an opportunity of advantage for the fish farming in coffee farms with limited supply of water.

In a fifth test, the utilization of biomass generated in the aquatic treatment systems was evaluated in the cultivation of edible and medicinal mushroom and in the production of organic fertilizer by means of earthworm breeding.

It was determined that the use of biomass of aquatic plants like supplement, in values of 16%, of the substrates, with by-products of coffee process, for the cultivation of edible mushroom of the genre Pleurotus, sort showed positive effects in the yield of the cultures, without altering the health of themselves and that the inclusion of biomass of the emergent plant, comprising of 50% of the total of biomass used like supplement, allowed to increase still more the yields, being reached values of 128,55% in the cultivation of edible mushroom Pleurotus pulmonarius and 103,85% in the cultivation of edible mushroom Pleurotus sajor caju.


The investigation also allowed to determine that the yields in the cultivation of edible mushroom of genre Pleurotus, using biomass of aquatic treatment systems as only substrate, were equal or inferior to the obtained using the biomass like supplement. It is inferred, considering the nutritional and economic value of harvested mushroom, that the best form of advantage of the aquatic biomass, in the coffee zone, is as supplement of the substrates used for the cultivation of edible mushroom.

It was determined the viability to use earthworm breeding for production of organic fertilizer from the biomass of aquatic treatment systems, being found a mean efficiency, in the process of worm composting, of 51,73% in dry weight.

The greater contents of NPK, by each 100 g of initial dry matter, were found in the vermicompost from as fresh as dehydrated biomass of T. angustifolia, followed of the vermicompost of E. crassipes, P. stratiotes and S. auriculata.

In average, the vermicompost obtained from originating biomass of aquatic treatment systems presented a fertilizing value of 5,38% N – 4,13% P2O5 – 18,18% K2O, reason why they could comprise of the programs of organic fertilization of coffee fields or cultures associated to the coffee zone, generating economic benefits for the producers.

Finally it concludes that is necessary to diminish the concentration of coffee honeyswaters anaerobically treated to values of COD below 1172 ppm to be able to use aquatic treatment systems and that integrated biosystem that uses a mixture of floating species E. crassipes, P. stratiotes and S. auriculata and in which the biomass generated takes advantage for elaboration of organic fertilizer by means of earthworm breeding process or as supplement of the used traditional substrates in the cultivation of edible mushroom is appropriate for the post-treatment of coffee honeyswaters in the Colombian coffee zone.

The present doctoral thesis generates an important contribution of new information for the design of integrated biosystem that uses aquatic macrophytes for the post-treatment of coffee honeyswaters anaerobically treated with the objective to help to consolidate an environmentally sustainable coffee growing, benefitting with it to more than 500000 Colombian coffee families.