Residual Sludge Research Articles

Production of polyhydroxyalkanoates from propylene oxide saponification wastewater residual sludge using volatile fatty acids and bacterial community succession

The active sludge treating propylene oxide saponification wastewater has heavy salt concentration and is hard to treat. The integration of the residual sludge treatment with polyhydroxyalkanoates (PHA) production may provide an economic and environment friendly solution. PHA production was therefore studied in two sequencing biological reactors with effective volume of 30 L using the active sludge. The two reactors, named as SBR-I and SBR-II, were fed with acetic acid, and a mixture of acetic acid and propionic acid respectively. PHA was obtained with a yield of 9.257 g/L in SBR-II. Also, the proportion of 3-hydroxyvalarate was enhanced from 5% to 30% in comparison to SBR-I (5.471 g/L). Illumina MiSeq and Pacific Biosciences sequencing platforms were used to evaluate the community structure, which revealed that the bacterial genera showed a high degree of diversity in the PHA accumulating microbial community. Azoarcus was the most dominant PHA accumulating microorganism after acclimation.

The effect of municipal sewage sludge on properties physicochemical and microbial agricultural soil

The organic matter content of sludge can improve the physical, chemical and biological properties of the soil ensuring better cultivation and good agricultural productivity. The objective of this study is to evaluate the effect of sewage sludge on the main physicochemical and biological properties of the soil. The sludge was spread in an agricultural field in Ain defla (Algeria) cultivated with a tomato crop (‘Panikra’) in four treatments: (T): soil without sewage sludge and without mineral fertilization, (B): soil with sewage sludge, (E): soil with mineral fertilization, (B + E): soil with sewage sludge and mineral fertilization. For this, several physical, chemical and microbiological properties were analyzed on the residual sludge used and the soils collected in the studied plots. The results show that the sludge used does not exhibit any toxicity and that the treatment with the sewage sludge with the fertilizer used on the agricultural soil forms a better compost for improving the physicochemical quality of the soil compared to the other treatments. The application of sewage sludge also can accelerate microbial activity by increasing the number of bacteria, fungi and azotobacter.

Modeling energy requirements for a biogas-supported decentralized Water treatment systems for communities in chambishi (Zambia) and diepsloot (South Africa) townships

An analytical model to determine energy requirements for a Biogas-supported Decentralized Water Treatment Systems was carried out based on energy consumption in Zambia and energy produced during water reclamation from wastewater in South Africa.For Zambia, the power consumption of the pumps for water abstraction, suction, distribution and treatment was the basis for determining energy required per hour. This energy was provided by biogas which was produced from a mixed feedstock of equal proportions made up of food leftovers, sewage sludge and fecal matter. This energy and amount of feedstock were used to design the biodigester. The model determined that a 1400 m3 biodigester with biogas output of 8.6 ML/day could yield 57 kW electricity. These results compare proportionally very closely with those of the Safi Sana plant which has a 2500 m3 biodigester and produces 100 kW electricityFor South Africa, energy requirements were modeled using experimental data obtained from water reclamation of wastewater and using sludge residue to produce biogas for electricity. This experimental model determined that 618 ML/day of wastewater could be processed to yield power generation of 4.2 MW h, an upscale from the current 97 ML of wastewater per day that generates 1.1 MW h.

Metagenomic analysis revealed the microbiota and metabolic function during co-composting of food waste and residual sludge for nitrogen and phosphorus transformation

This paper used bagasse as a composting additive and bulking agent in order to investigate the aerobic composting process of food waste and residual sludge. Accordingly, the variations of nitrogen and phosphorus nutrients, microbiota and metabolic function during the composting process were systematically explored. Three piles with residual sludge, food waste and bagasse mass ratios of 1:1:1, 2:1:1 and 4:1:1 were set. The ammonia nitrogen content in the three compost piles were 3.18 mg/g, 4.68 mg/g and 5.84 mg/g at the end of composting. The final available phosphorus content of the three piles were 3.42 mg/g, 6.70 mg/g and 11.21 mg/g, respectively. X-ray photoelectron spectroscopy (XPS) analysis showed that absorption peaks attributed to amines, amino acids and amides appeared in the 1:1:1 pile. Metagenomic analysis of the glycolysis and ammonia transformation pathways showed that the total relative abundance of key enzyme genes for the conversion of glucose to glucose-6-phosphate in the three plies were 0.326%, 0.213% and 0.248%, respectively. The total relative abundance of 2 glutamate dehydrogenase (GDH2), glud1–2 and E1,4,1,4 dehydrogenases in the three piles was 0.125%, 0.151% and 0.160%, respectively, as the main enzymes for the mutual conversion of ammonia and glutamate.

Enrichment and retention of key functional bacteria of partial denitrification-Anammox (PD/A) process via cell immobilization: A novel strategy for fast PD/A application

Cell immobilization was used to enrich and retain functional bacteria within partial denitrification-Anammox (PD/A) process to achieve its fast start-up for the first time. To do so, residue sludge and Anammox sludge were immobilized in poly (vinyl alcohol)/sodium alginate (PVA/SA) gel for PD cultivation and Anammox bacteria inoculation, respectively. Stable PD with NO3−-N to NO2−-N transformation ratio (NTR) of 72.0% was achieved within 13 days at 25 °C and successfully combined with Anammox on 14th day. The hydrous porous PVA/SA gel matrix played the role of extracellular polymeric substance (EPS) and thus protected the microbes against low temperature. Satisfactory nitrogen removal rate (NRR) (301.6 ± 6.1 g N/(m3·d)) was achieved even when temperature decreased to 13 °C. The contribution of nitrogen removal via Anammox was as high as 77.10%. Abundance of Thauera and Candidatus Kuenenia increased from 0.9% and 1.1% to 30.6% and 2.1%, respectively.

Removal of ammonia nitrogen and phosphorus by biochar prepared from sludge residue after rusty scrap iron and reduced iron powder enhanced fermentation

The rusty scrap iron (RSI) or a mixture of rusty scrap iron and reduced iron powder (RSI-RIP) can be used as an exogenous additive to enhance the anaerobic fermentation of sewage sludge. In order to make rational use of the fermentation residue, the sludge after intensified fermentation was pyrolyzed to produce biochar in this study, which was used in the adsorption of ammonia and phosphorus from the anaerobic fermentation broth. The experimental results demonstrated that the pore structure of the sludge biochar was greatly improved after enhanced fermentation with RSI and RIP. Meanwhile, there was an increase in the proportion of metallic elements such as Ca, Fe and Mg. On the other hand, the RSI-RIP co-enhanced fermented biochar (ES600) prepared at 600 °C showed a higher adsorption capacity, which was comparable to the commercially activated carbon. Neutral or weakly alkaline environments were preferred during the adsorption process. At a suitable pH condition, the maximum removal efficiency of ammonia nitrogen (NH4+-N) and total phosphorus (TP) on ES600 reached 91.3% and 98.6%, respectively. In addition, the saturated ES600 was regenerated by simple washing with ammonia-free water. After three cycles, the removal efficiency of NH4+-N and TP remained at 71.3% and 83.2%, respectively. As a result, the biochar prepared from RSI-RIP enhanced fermented sludge can be used as a promising low-cost adsorbent.

Эффективность анаэробной переработки органических отходов в биофильтрах с использованием кондуктивного носителя

Additional anaerobic treatment of the liquid fraction of the methantenk’s effluent to the content of organic substances that ensure subsequent effective processing under aerobic conditions can be carried out in a biofilter. Processing makes it possible to obtain an additional amount of biogas, reduce the volume of sludge residues. To accelerate the processes of wastewater treatment and optimize the processes of anaerobic processing of wastewater, the use of conductive carriers of inorganic biomass is promising. (Research purpose) The research purpose is in studying the effect of conductive biomass carriers on the efficiency of anaerobic processing of organic waste in biofilters. (Materials and methods) The liquid fraction of the effluent obtained as a result of the gravitational separation of the effluent of the methantenk was used as a substrate for the biofilter. The article describes experimental studies on a test bench that includes two identical bioreactors, in one of which there was placed a biomaterial carrier made of carbon tissue. The article presents a technological scheme and an experimental installation for anaerobic post-treatment of the liquid effluent fraction. (Results and discussion) In the course of experimental studies for 25 days, they showed high stability of the operation of the developed and manufactured experimental installation. In the recycled effluent of a bioreactor with a conductive carrier, the organic substances of the effluent are more fully processed into biogas. The specific (in terms of unit volume of the bioreactor) yields of biogas and methane increased by 14.0 and 22.5 percent; the specific methane yield per gram of raw and decomposed organic matter increased by 22.2 and 7.3 percent. (Conclusions) The use of a biofilter in combination with the immobilization of microorganisms on a conductive carrier allowed to increase the efficiency of fermentation of organic waste by 6 percent, increase the specific yields of biogas and methane, and reduce the volume of sludge residues.

Performance, carcass characteristic and apparent nutrient digestibility of broiler chickens fed Palm-kernel extraction by-products

This study aimed at investigating the effect of by-products of palm kernel extraction; palm kernel extraction residue (PKER) and palm kernel sludge (PKS) based diets as replacement for maize in broiler diets. A total of 198 one-day old Marshal Broiler chickens were randomly assigned to six dietary treatments. Each dietary treatment had 33 birds with 11 birds per replicate. Maize in the diets was partly replaced by PKER and PKS each at three levels (0, 10 and 20%). The experiment was conducted in both starter and finisher phases. Growth responses, carcass evaluation and nutrient utilization were estimated. Data obtained were subjected to 2x3 factorial arrangement within the completely randomized design (CRD). Feed: Gain was influenced by the level of the palm kernel by-products during 1-28days of study. The weight gained during the 56 days period were not significantly higher (P>0.05) across the treatments All the carcass parameters measured were not significantly (P>0.05) affected by either PKER or PKS. However birds on PKER diets showed superior (P<0.05) nutrients use. In conclusion, the inclusion of palm kernel extraction by-products (between 10-20% PKER and 20% PKS) in the diets of broiler chickens is thereby encouraged for better growth and efficient feed utilization.

Hydrothermal treatment and biorefinery of sewage sludge for waste reduction and production of fungal hyphae fibers and volatile fatty acids

Sewage sludge poses a serious environmental problem for large cities, and large amounts of materials in sludge, including organics, should be recovered rather than wasted. To achieve both sludge reduction and organic resource recovery, this study developed a new biorefinery technology that includes the hydrothermal treatment of sludge followed by fungal fermentation to form hyphae fibers and acidogenic fermentation to produce volatile fatty acids (VFAs). Hydrothermal treatment at 160 °C or 180 °C allows solubilization of approximately 40% of solid organics in sludge into the supernatant, resulting in significant sludge reduction and dewaterability improvement. The fermentation of the fungus Aspergillus niger converted waste organics in the hydrolyzed sludge liquor, with a chemical oxygen demand (COD) concentration of around 15,000 mg/L, into hyphae fibers, resulting in fungal biomass production of more than 1.7 g/L. After the recovery of hyphae fibers, the residual sludge liquor was further fermented to produce VFAs to a concentration of about 2500 mg COD/L. The genera Petrimonas, Arcobacter, and Aminobacterium played important roles in acidogenic fermentation. The stepped biorefinery strategy can transform approximately 35% of waste organics in the hydrothermal sludge liquor into valuable fibrous materials and VFAs for effective resource recovery.

Evalution of the fate of greenhouse gas emissions from the sludge mineralisation process in Sludge Treatment Wetlands

Mineralisation process of Greenhouse gas (GHG) emission data from a sludge treatment wetlands (STWs) has been lacked currently. A study was conducted to quantify the release rates of carbon dioxide (CO2) and methane (CH4) from three similar pilot-scale STW units in relation to seasonal change based on the release rates in order to estimate annual GHG release rates of mineralisation process. A static transparent chamber was adopted to measure gas emission without interference of absorption of sunlight by plants for photosynthesis. The three pilot configurations were unit STW1 with ventilation, unit STW2 with ventilation and reed plantings and unit STW3 with reed plantings; all located at Dakai wastewater treatment plant (WWTP), Dalian, China. The resting and loading periods were measured from April to November 2016 and then from April to November 2017, respectively. The results revealed that the release rates of CO2 and CH4 were significantly influenced by seasonal change: the highest release rates were recorded in summer and the lowest rates were recorded in winter. During both seasons, CH4 releases during the resting period (negligible to 2.96 mg CH4 m−2 d−1) were lower than that during the loading period (34 to 1492 CH4 mg mm−2 d−1) while CO2releases were higher during the resting period (1368 to 81,911 mg CO2 m−2 d−1) than that of the loading period (1351 to 30,872 mg CO2 m−2 d−1). Additionally, the presence of plants showed significant impact on GHG emissions i.e. CH4 emissions from STW2 and STW3 were higher than that of STW1. Comparison of data between STW2 and STW3 showed that CH4 and CO2 emissions were reduced in the presence of ventilation. Meanwhile, the measurement of residual sludge moisture content showed that STW2 had higher dewatering and mineralisation efficiencies compared to STW3 and STW1. The annual CO2-eq CH4 emissions from the three STWs during loading and resting periods were in sequence as STW3 > STW2 > STW1, and the recorded annual CO2-eq CH4 during the loading period was higher than that during the resting period.

Biofertilizer potential of digestates from small-scale biogas plants in the Cuban context

The residual sludge from anaerobic digestion known as digestate has been used as a valuable biofertilizer, but the effect of the substrate, the configuration of the reactor and the operating parameter changes the quality and amounts of nutrients in it. Therefore, it is necessary to know its potential characteristic of fertilizer to apply it correctly in crops of national interest. The aim of this work was to characterize the digestate generated from three biodigester technologies (fixed dome, floating drum and tubular) and three substrates: swine manure, cow manure, and co-digestion of swine and cow manure obtained in the province of Sancti Spíritus, Cuba, in terms of nutrient and matter content. For this purpose, stratified statistical sampling was carried out to ensure representative samples and descriptive statistical techniques were used to process the analyses. The digestate was divided into liquid and solid fractions according to the dry matter content (15%). The content of organic matter and ash represented around 50% for both fractions, which enhances its value as a soil conditioner. The nutrient content of both fractions showed good fertilizing properties, having a nutrient ratio (NH4+:PO43-:K+:SO42-:Mg2+:Ca2+) in the liquid (0.002:0.80:0.10:1.00:0.89:0.93) and solid (0.0003:0.96:0.002:1.00:0.52:0.50) fractions, that would contribute to the return nutrients to the soil. The quality of the liquid fraction as irrigation water was assessed as good, according to the relationship between the concentration of the nutrients (Ca, Mg, Na and K) and hardness. Further research is needed on the appropriate dosage for the different crops, and its contribution to sustainable agriculture in the Cuban context.

Analisis Kebutuhan Bak Penampung Lumpur IPA sebagai Upaya Pengendalian Dampak Lingkungan

Sand Drying Bed (SDB) is designed for reducing the potential environmental impact caused by Water Treatment Plants – WTP residuals. Currently, the technical document of SNI (Indonesian National Standard) is still difficult to be applied by the engineer in determining required SDB’s volume based on WTP’s capacity and raw water conditions. The purpose of this research is to analyze WTP’s sludge production for designing SDB’s volume. The research was taken place at Pajangan WTP (50 l/s capacity) and Bantar System of Kartamantul WTP (400 l/s capacity) in Yogyakarta Special Province, which use Progo River as raw water source. The data used in the analysis is raw water turbidity compilation data, TSS (Total Suspended Solid) fluctuations rate of raw water, coagulant dosage used, specific gravity range of dried sludge and imhoff settling ratio based on laboratory tests. The results obtained show that one-year production of dry sludge on Pajangan WTP Unit is estimated to reach 244.55 m3/year from the total number of WTP residual (water and sludge) produced of around 43,158.52 m3/year. Meanwhile, the dry sludge produced on Kartamantul WTP Unit is estimated to reach 1,550.49 m3/year from the total number of WTP residual produced of around 273,635.22 m3/year. Then, each of Pajangan and Kartamantul WTP unit produced about 2.365 m3/day and 1.874 m3/day sludge for every 1 liter/second of raw water. This large amount of sludge leads the SDB has to be better designed.

Emission characteristics of bioaerosol and quantitative microbiological risk assessment for equipping individuals with various personal protective equipment in a WWTP

Wastewater treatment plants (WWTPs) are a nonnegligible source of bioaerosols that can pose health risks to workers and nearby residents. Thus, this study systematically investigated the emission characteristics of the size distribution and concentration of Staphylococcus aureus bioaerosol in a WWTP. Then, the research focused on the quantitative microbiological risk assessment (QMRA) of workers and nearby residents for equipping them with various grades personal protective equipment (PPE). Results showed that the peak proportion of the size distributions of bioaerosol particles in the three sources all obtained a size range between 3.3 and 4.7 μm. In the residential building, the peak proportion was larger (>7.0 μm). Referring to the three sources, the average bioaerosol concentrations were in the following sequence: inverted umbrella aerator tank > residual sludge storage yard > microporous aerator tank. The health risks of residents were generally 1–2 orders of magnitude higher than the other two exposure scenarios and were clearly beyond the benchmarks. Meanwhile, the health risks of the field engineer were usually lower than those of the staff at the residual sludge storage yard. In general, equipping workers and residents with PPE could at least decrease the health risks by one order of magnitude, and higher-grade PPE could appropriately promote the reduction of health risks. This research systematically delivered a series of novel data about the emission characteristics of Staphylococcus aureus bioaerosol in a WWTP. It advanced the understanding of the quantitative health risks of equipping individuals with various PPE.

Performance of sludge degradation, mineralization and electro-energy harvesting in a sludge treatment electro-wetland: Insight into the sludge loading rate

In order to enhance the performance of sludge treatment wetland (STW), microbial electrochemical system (MES) was introduced into a conventional sludge treatment wetland. A sludge treatment electro-wetland (STEW) was specially developed and investigated for its performance in sludge treatment and bioenergy production. The study investigated the performance of the STEW in terms of sludge organic degradability, sludge stabilization and the capability of bioelectricity generation at different sludge loading rates (SLR) of 50, 95, 125 kg TS/year·m2. The quality of the final residual sludge product for agricultural reuse was also characterized. Results revealed that the highest power output (0.790 V of voltage and 0.229 W/m3 of power density) of STEW was achieved with the highest SLR (125 kg TS/year·m2). The best sludge treatment efficiency (7.07 % of dewatering rate, 40.43 % of volatile solid (VS) removal and 80.95 % of total chemical oxygen demand (TCOD) removal) of STEW were achieved with proper SLR of 95 kg TS/year·m2. After resting period, the nutrient concentrations in the residual sludge were quite low (total nitrogen of 2.86 % total solid (TS) and total phosphorous of 0.93 %TS), and heavy metals and faecal bacteria (Salmonella spp. and Escherichia coli) concentrations remained within the current legal limits for land application of the sludge. Experiments showed that the STEW system demonstrated a satisfactory efficiency for sludge dewatering and mineralization in spite of the high sludge loading rate and recycled the bioenergy simultaneously. The results also illustrated that the STEW was a promising technology for simultaneous sludge treatment and energy recovery.

Fenton oxidative degradation of spent organic solvents from nuclear fuel reprocessing plant

The treatment and disposal of the spent organic solvents is a crucial step in minimizing wastes from nuclear fuel reprocessing in a closed fuel cycle that will enable the sustainable development of nuclear energy. In this study, the Fenton oxidation was used for the stabilization and volume reduction of the spent organic solvents - tributyl phosphate/odourless kerosene (TBP/OK = 9/21 (v/v)). The parameters of the Fenton oxidation for the spent organic solvents were optimized. The volume reduction efficiency reached 93%, and more than 35% of TBP/OK was degraded. The composition of the aqueous and oil phases of both the Fenton residual liquid and the off-gas condensate was analyzed according to the experimental results of Fourier transform infrared (FTIR), elemental analysis and ion chromatography (IC). The residual sludge contained Fe(OH)3, Fe(OH)2, FePO4·2H2O and TBP/OK degradation products. The possible degradation pathway of TBP/OK was proposed. The results of this study may provide useful information for subsequent treatment and disposal of the spent organic solvents.

Selective Removal of Zinc from BOF Sludge by Leaching with Mixtures of Ammonia and Ammonium Carbonate

The zinc content of basic oxygen furnace (BOF) sludges is too high for direct recycling into the blast furnace via the sinter plant, as excessive zinc concentrations are detrimental for the refractory lining of the blast furnace. However, by partial and selective removal of zinc from the BOF sludge, the residual sludge can be used as a secondary iron resource in the blast furnace. In this paper, BOF sludge was leached with aqueous ammonia, aqueous solutions of ammonium salts (chloride, carbonate, and sulfate), and aqueous mixtures of ammonia and ammonium salt. The mixtures of ammonia and ammonium salt could leach more zinc with respect to either the aqueous ammonia or the aqueous ammonium salt solution. The ammonia–ammonium carbonate (AAC) mixture was selected as the most suitable lixiviant due to the high zinc leaching efficiency in combination with a high selectivity towards iron; furthermore, this combination does not introduce unwanted chloride or sulfate impurities in the residue. The leaching process was optimized in terms of the liquid-to-solid ratio, total ammonia concentration, ammonium:ammonia molar ratio, temperature, and leaching time. The co-dissolved iron was precipitated as a hydroxide after oxidation of ferrous to ferric ions by an air stream, without co-precipitation of zinc, while the dissolved zinc could be easily recovered as zinc sulfide by precipitation with ammonium sulfide. The (almost) closed-loop process was successfully up-scaled from 10 mL to 1 L scale.Graphical

Assessment of the energy recovery potential of oil sludge through gasification aiming electricity generation

Thermochemical conversion of oil sludge (OS) residues from crude oil refinery was studied as an alternative for treatment and energy recovery before OS final disposal. A simulation model for OS gasification was developed and validated by using AspenPlus™ V 11.0. Three scenarios by considering different gasifying agents were evaluated, aiming the assessment of different gasification parameters and performance indexes such as gasification temperature, cold-gas efficiency, syngas yield, and LHV. To evaluate the potential use of syngas to generate electricity, three different prime movers such as steam Rankine cycle, gas microturbine, and gas-Internal Combustion Engine (ICE) were modeled. A hydrogen-rich syngas from OS gasification with air/steam mixture was reached (38.2 vol%) at ER 0.20. Syngas LHV and syngas yield ranged between 8.6 and 3.0 MJ/Nm3 and 0.6–1.3 Nm3/kg OS, when ER was increased from 0.25 to 0.45, respectively. The highest energy recovery potential (electricity generation) was obtained when using syngas to power a gas-ICE, with a generation index of about 0.47 kWh/kg-OS at ER ratio of 0.25. Therefore, OS thermochemical conversion into syngas and its subsequent use to generate electricity could be a technological alternative to oily residues management inside an oil refinery that could efficiently transform a dangerous residue into electricity.

Study on adsorption of lead and cadmium by non-burning ceramic granules from waterworks residual sludge

In this experiment, the unburned ceramiste water treatment residuals (UCWTR) was prepared by the burning-free method to study its adsorption performance on Pb and Cd. Adsorption experiments show that the quality of ceramsite improved with the height of the filler layer in the reaction column, and its penetration and depletion time are prolonged. On the contrary, the driving force of mass transfer increases with the initial concentration of water in the reaction column, and the penetration and exhaustion time is shortened. The dynamic adsorption process of Pb and Cd by UCWTR is more consistent with the Thomas model and Yoon-Nelson model, and the correlation coefficient R2 is greater than 0.9. Under the condition that the initial flow rate v is 10 mL/min, the height of the packing layer h is 10 cm, and the initial concentration C0 is 150 mg/g, the fitted dynamic saturated adsorption capacities of UCWTR for lead and cadmium are 9.22 mg/g, 11.52 mg/g, the static adsorption capacity of lead and cadmium are 1.48 times and 155 times respectively. kT decreases as the height of the filler layer and the initial concentration increase; kYN decreases as the height of the filler layer increases, and increases as the initial concentration increases; the time t required to penetrate 50% of the adsorbent increases with the height of the filler layer and decreases with the increase of the initial concentration, which indicated that the solution did not reach full contact with UCWTR during the dynamic adsorption process.

Study on Reutilization of Pyrolytic Residues of Oily Sludge.

Pyrolytic residues of oily sludge are a kind of hazardous solid waste produced by high-temperature pyrolysis of oily sludge, which still contains a certain amount of mineral oil; improper disposal can cause secondary pollution. In order to reutilize the pyrolytic residues of oily sludge, the pyrolytic carbon in pyrolytic residues is recovered by a combination of physical flotation and chemical separation, and they are used for the treatment of oilfield wastewater and adsorption of oil. The results showed that the purity of the pyrolytic carbon is 95.93%; many pores of different sizes are distributed on the surface, with mainly mesoporous distribution. Specific surface area, pore volume, and average pore diameter reach 454.47 m2/g, 0.61 cm3/g, and 6.91 nm, respectively. Adsorption effect of pyrolytic carbon on COD and oil in oilfield wastewater is better than that of activated carbon at the same condition. With regard to adsorption on diesel and crude oil, the initial instantaneous adsorption rate of pyrolytic carbon is 3.8 times and 1.86 times faster than that of activated carbon, respectively. When pyrolytic carbon reaches saturated adsorption, cumulative adsorption of activated carbon on diesel and crude oil is much lower than that of pyrolytic carbon.

Germinación y bioestimulación en Acacia farnesiana (L.) Willd y Ebenopsis ebano (Berl.) Barneby para la remoción de As, Cd y Zn de lodos residuales por extracción de gas shale en Tamaulipas

Introducción: En la actualidad, existe una creciente demanda de hidrocarburos, lo que ha provocado el empleo de tecnologías no convencionales como la fracturación hidráulica. Sin embargo, esta técnica ocasiona daños ambientales a los ecosistemas por la generación de lodos residuales, como es el caso del matorral espinoso tamaulipeco que se encuentra dentro de la Cuenca de Burgos, zona de relevancia económica para la explotación de gas convencional. El objetivo del estudio fue evaluar la germinación de Acacia farnesiana (L.) Willd y Ebenopsis ebano (Berl.) Barneby y su uso potencial con bioestimulación, en la remoción de As, Cd y Zn en lodos residuales provenientes de la extracción de gas shale. Método: Se colectaron semillas de Acacia farnesiana (L.) Willd y Ebenopsis ebano (Berl.) Barneby en el ejido El Zaus, municipio de Hidalgo, Tamaulipas. Se evaluó el índice de germinación (IG) de acuerdo con Zucconi. Los tratamientos fueron 23, considerando los sustratos (dos tipos de lodo, suelo y una mezcla de ambos sustratos), las dos especies de plántulas (Acacia y Ebenopsis) y la bioestimulación donde se utilizó una solución de urea al 46 %. Se utilizaron macetas de tres kilogramos como unidades experimentales, donde se sembraron tres plántulas con tres repeticiones por tratamiento. Se realizó un muestreo final de cada tratamiento para las determinaciones correspondientes de As, Cd, Zn, P y K, las cuales se realizaron por extracción de (DTPA), y posteriormente se llevaron a espectroscopia de emisión atómica de inducción por plasma (ICP-OES Varian modelo 725-ES, Agilent Mulgrave, Australia). El Nitrógeno total, en plántulas y sustratos, se realizó por el método micro Kjeldahl, y la materia orgánica (MO) por Walkely Black.Resultados: Se observaron diferencias en IG (P = 0.02374). Los resultados indican que las características estructurales (tamaño) y fisiológicas (viabilidad del embrión) de las semillas están relacionadas con la capacidad de germinación de estas especies en sustratos contaminados. Se encontraron diferencias significativas en la concentración de As, Cd, y Zn, a través del tratamiento (P < 0.0001). La acumulación de As, Cd y Zn, fue determinada por la estructura de la planta (raíz > tallo >hoja).Conclusión: El índice de germinación de Acacia farnesiana (L.) Willd y Ebenopsis ebano (Berl.) Barneby, en sustratos acuosos de lodos residuales provenientes de la extracción de gas shale, se sustenta en las características estructurales y fisiológicas de cada especie. La remoción de As, Cd y Zn, estuvo influenciada por la especie, el sustrato, la bioestimulación con la urea y la presencia de MO que confiere el efecto tapón que controló la alcalinidad de los sustratos y, por ende, la movilidad de los metales.