Marina Gladchenko

One- and two-stage upflow anaerobic sludge-bed reactor pretreatment of winery wastewater at 4–10°C

The operating performance of a single and two (in series) laboratory upflow anaerobic sludge-bed (UASB) reactors (2.7-L working volume, recycle ratio varied from 1:1 to 1:18) treating diluted wine vinasse was investigated under psychrophilic conditions (4–10°C). For a single UASB reactor seeded with granular sludge, the average organic loading rates (OLRs) applied were 4.7, 3.7, and 1.7 g of chemical oxygen demand (COD)/(L·d) (hydraulic retention times [HRTs] were about 1 d) at 9–11, 6 to 7, and 4 to 5°C, respectively. The average total COD removal for preacidified vinasse wastewater was about 60% for all the temperature regimes tested. For two UASB reactors in series, the average total COD removal for treatment of non-preacidified wastewater exceeded 70% (the average OLRs for a whole system were 2.2, 1.8, and 1.3 g of COD/[L·d] under HRTs of 2 d at 10, 7, and 4°C, respectively). In situ determinations of kinetic sludge characteristics (apparent Vm and Km) revealed the existence of substantial mass transfer limitations for the soluble substrates inside the reactor sludge bed. Therefore, application of higher recycle ratios is essential for enhancement of UASB pretreatment under psychrophilic conditions. The produced anaerobic effluents were shown to be efficiently posttreated aerobically: final effluent COD concentrations were about 0.1 g/L. Successful operation of the UASB reactors at quite low temperatures (4–10°C) opens some perspectives for application of high-rate anaerobic pretreatment at ambient temperatures.

Combined biologic (anaerobic-aerobic) and chemical treatment of starch industry wastewater

A combined biologic and chemical treatment of high-strength (total chemical oxygen demand [CODtot] up to 20 g/L), strong nitrogenous (total N up to 1 g/L), and phosphoric (total P up to 0.4 g/L) starch industry wastewater was investigated at laboratory-scale level. As a principal step for COD elimination, upflow anaerobic sludge bed reactor performance was investigated at 30°C. Under hydraulic retention times (HRTs) of about 1 d, when the organic loading rates were higher than 15g of COD/(L·d), the CODtot removal varied between 77 and 93%, giving effluents with a COD/N ratio of 4–5∶1, approaching the requirements of subsequent denitrification. The activated sludge reactor operating in aerobic-anoxic regime (HRT of about 4 d, duration of aerobic and anoxic phases of 30 min each) was able to remove up to 90% of total nitrogen and up to 64% of CODtot from the anaerobic effluents under 17–20°C. The coagulation experiments with Fe(III) showed that 1.4 mg of resting hardly biodegradable COD and 0.5 mg of phosphate (as P) could be removed from the aerobic effluents by each milligram of iron added.

Development and optimisation of VFA driven DEAMOX process for treatment of strong nitrogenous anaerobic effluents.

The recently proposed DEAMOX (DEnitrifying AMmonium OXidation) process combines the anammox reaction with autotrophic denitrifying conditions using sulphide as an electron donor for the production of nitrite from nitrate within an anaerobic biofilm. This paper firstly presents a feasibility study of the DEAMOX process using synthetic (ammonia + nitrate) wastewater where sulphide is replaced by volatile fatty acids (VFA) as a more widespread electron donor for partial denitrification. Under the influent N-NH+4/N-NO3(-) and COD/N-NO3(-) ratios of 1 and 2.3, respectively, the typical efficiencies of ammonia removal were around 40% (no matter whether a VFA mixture or only acetate were used) for nitrogen loading rates (NLR) up to 1236 mg N/l/d. This parameter increased to 80% by increasing the influent COD/N-NO3(-) ratio to 3.48 and decreasing the influent N-NH4 +/N-NO3(-) ratio to 0.29. As a result, the total nitrogen removal increased to 95%. The proposed process was further tested with typical strong nitrogenous effluent such as reject water (total N, 530-566 mg N/l; total COD, 1530-1780 mg/l) after thermophilic sludge anaerobic digestion. For this, the raw wastewater was split and partially ( approximately 50%) fed to a nitrifying reactor (to generate nitrate) and the remaining part ( approximately 50%) was directed to the DEAMOX reactor where this stream was mixed with the nitrified effluent. Stable process performance up to NLR of 1,243 mg N/l/d in the DEAMOX reactor was achieved resulting in 40, 100, and 66% removal of ammonia, NOx(-), and total nitrogen, respectively.

The UASB Treatment of Winery Wastewater under Submesophilic and Psychrophilic Conditions

The start-up and operational performance of two laboratory UASB reactors (working volume of 2.6 l) treating diluted vinasse (1-17 g COD l−1) were investigated at 35 °C (run 1, without recycle), 19-21°C (run 2, without recycle), 18-20°C (run 3, with recycle 1:1) and 9-10 °C (run 4, with recycle 1:2.6). The reactors for runs 1 and 2 were seeded with flocculant mesophilic sludge. For runs 3 and 4, the reactor seed sludge was upgraded by addition of 30% of psychrotrophically adapted granular sludge. A successful start-up of the reactors for all runs was achieved in 2-3 months. The maximum applied organic loading rates (OLR) were 15.9, 6.5, 12.5 and 7.2 g CODl−1d−1 for runs 1-4, respectively. Hydraulic retention times at these loadings were around or less than 1 day. The total COD removals achieved under these OLR were higher than 85% for the first 3 runs and higher than 60% for run 4 with substantial decoloration of effluents (reduction of polyphenol content varied between 45-67%).

Removal of Chemical Oxygen Demand, Nitrogen, and Heavy Metals Using a Sequenced Anaerobic-Aerobic Treatment of Landfill Leachates at 10-30°C

As a first step of treatment of landfill leachates (total chemical oxygen demand [COD]: 1.43–3.81 g/L; total nitrogen: 90–162 mg/L), performance of laboratory upflow anaerobic sludge bed reactors was investigated under mesophilic (30°C), submesophilic (20°C), and psychrophilic (10°C) conditions. Under hydraulic retention times (HRTs) of about 0.3 d, when the average organic loading rates (OLRs) were about 5 g of COD/(L·d), the total COD removal accounted for 81% (on average) with the effluent concentrations close to the anaerobic biodegradability limit (0.25 g of COD/L) for mesophilic and submesophilic regimes. The psychrophilic treatment conducted under an average HRT of 0.34 d and an average OLR of 4.22 g of ducted under an average HRT of 0.34 d and an average OLR of 4.22 g of COD/(L·d) showed a total COD removal of 47%, giving effluents (0.75 g of COD/L) more suitable for subsequent biologic nitrogen removal. All three anaerobic regimes used for leachate treatment were quite efficient for elimination of heavy metals (Fe, Zn, Cu, Pb, Cd) by concomitant precipitation in the form of insoluble sulfides inside the sludge bed. The application of aerobic/anoxic biofilter as a sole polishing step for psychrophilic anaerobic effluents was acceptable for elimination of biodegradable COD and nitrogen approaching the current standards for direct discharge of treated waste-water.

The optimization of the conversion of agricultural waste into volatile fatty acids under anaerobic conditions

The selection of a biocatalyst was performed and the first optimal microbial association was obtained. This association was capable of converting products of depolymerization of sawdust, straw, and lignin into volatile fatty acids with an acid-producing activity that was greater by 1.3 times than the initial methane activity. The largest percentages of butyric acid (40%) and ethanol (14%) were obtained from biomass out of straw in concentrations of soluble organic substances from 2.5 to 6.3 gCOD/L. Using biomass from sawdust and lignin at concentrations of organic substances from 4.0 to 8.0 gCOD/L and a duration of the conversion process of up to 18 days we obtained an output of butyric acid that was two times smaller than that on a biomass from straw.

Influence of various degradation conditions on the properties of gas-generating soils in the process of their decontamination

The properties of gas-generating soils (GGS) in the process of biofermentation under anaerobic and aerobic conditions are studied. The degradation of organic matter (OM) in a soil under natural occurrence conditions (without free access of air oxygen) at temperatures from 10 to 12°C is demonstrated to proceed at a specific reaction rate of k = 0.096 year−1. The main phase of gas generation (biogas formation) is shown to take 15 years, with the content of methane in the biogas being 60−80 vol %. It has been established that, under the conditions of forced aeration of the GGS array, the specific reaction rate of OM degradation increases 10-fold, to 0.9673 year−1, with a nearly complete decomposition of OM taking 1.5−2.0 years. A prerequisite for achieving of the predicted result is the maintenance of the environment humidity at a level not lower than 50%. Application of an alternative method, a thermal treatment of GGS increases the degree of OM decomposition to 59% within 4 h at 200°C and to 75% within 2 h at 300°C. In this case, residual organic substances are carbonized in the course of thermal treatment, transforming into a material resistant to microbiological decomposition. In fact, after heating at 200−300°C, GGS becomes inert from the gas-geochemical point of view.

Effect of a preliminary physicochemical treatment of bituminous crusts resulting from oil pollution on the bioremediation of upland swamps with oil decomposers

Physicochemical preprocessing of a bituminous crust resulting from oil pollution by various reagents capable of hydrolyzing its structure, followed by aerobic degradation of hydrocarbons (HC) with the Rhoder bacterial oil-degrading preparation, was carried out. The crust was hydrolyzed with hydrogen dioxide, calcium hydroxide, and alkaline hydrolysate of crop production waste in concentrations from 2 to 20%. The best results in the destruction of the bituminous crust were obtained for processing the upper layer (0−2 cm) of the soil with calcium hydroxide, which resulted in an increase of the humidity of the hydrolyzed layer from 24 to 77%. The destruction of the bituminous crust with chemical agents made it possible to increase the effectiveness of biodegradation of HC from 9.97 to 26.40% in the upper soil layer and from 0.00 to 48.20% in the bottom soil layer. The kinetic characteristics of biodegradation after preprocessing, namely the rate constants of degradation and half-lives of HC were determined, the maximum values of which were found to be 0.015 day−1 and 47 days and 0.032 day−1 and 22 days for the upper and bottom soil layers, respectively.