Growing Spirodela polyrrhiza in Swine Wastewater for the Production of Animal Feed and Fuel Ethanol: A Pilot Study

To evaluate the performance of Spirodela polyrrhiza grown in swine wastewater for protein and starch production under field conditions, a pilot‐scale duckweed culture pond was installed at Barham Farm, Zebulon, North Carolina and operated from May to November 2010. The anaerobically treated swine wastewater was fed to the duckweed pond intermittently to provide nutrients for the growth of duckweed, and the duckweed biomass was harvested regularly from the pond and prepared as a protein‐ or starch‐rich feedstock for the production of animal feed or fuel ethanol. Over the experimental period, the duckweed pond produced protein and starch at rates of 2.68 and 1.88 g m^?2 day^?1, respectively. During the same time, NH₄–N and o‐PO₄–P in the wastewater were, respectively, removed at rates of 92.9 and 2.90 mmol m^?2 day^?1.     

Multifaceted Role of Microalgae for Municipal Wastewater Treatment: A Futuristic Outlook toward Wastewater Management

Municipal wastewater (MWW) or urban wastewater (UWW) is generated by the domestic consumption of freshwater, which contains a huge amount of nutrients. The release of unprocessed wastewater causes eutrophication and harms aquatic life. Moreover, ingestion of polluted MWW causes a severe negative impact on human health. Microalgae are unicellular, eukaryotic photosynthetic organisms and have the capability of nutrient assimilation in the presence of light. Moreover, the produced biomass can be used for the generation of value-added bioproducts such as bioenergy. However, conventional microalgae-based MWW treatment is not as sustainable on a commercial scale. Therefore, more advanced approaches using microalgae need to be integrated in wastewater cultivation systems to improve nutrient removal efficiency. Thus, the present review explores the use of microalgae for the removal of nutrients from MWW, provides an outlook of direct and indirect methods of nutrient uptake from wastewater and the effects of the influencing factors in biomass growth. Moreover, the review also gives insight into recent approaches used for MWW treatment and the applications of algal biomass resulting from treated wastewater. It is predicted that microalgae-based MWW treatment systems will be a significant green approach to help eliminate nutrient loads and implement circular economy.     

Uptake of macroelements by the helophytePhalaris arundinacea L.

Helophytes are often incorporated into biological wastewater treatment plants. In favourable situations, they can take up large amounts of nutrients. One helophyte, the reed canarygrass (Phalaris arundinacea L.), is fast growing when supplied with sufficient light and nutrients. Experiments were carried out under natural climatic conditions in small plastic tanks filled with sand with regular additions of a balanced and concentrated nutrient solution. In the growing season (May–October), plant production reached 10.5 kg m^–2 of dry biomass, of which 66% was in the aerial parts. Maximum nutrient uptake capacity was reached just after flowering and before senescence (beginning of October): 49% N, 34% P, 52% K and 34% Mg of the input was fixed in the aerial parts, which are easily harvestable. The corresponding values for the below ground parts were 12%, 10%, 11% and 11% respectively. Excretion of K and Mg has been observed when nutrients are translocated to the storage organs.     

Some Advantages of the Duckweed Test to Assess the Toxicity of Environmental Samples

In Germany, wastewater legislation requires all municipal and industrial leachate to be subjected to toxicity tests. However, no phytotoxicity tests using higher plants are currently included among the standard tests. Freshwater microalgae have been used in most phytotoxicity tests and have often been considered as surrogates for higher plants. However, microalgae often do not show the same sensitivity as higher plants and have major disadvantages for the testing of unmodified environmental samples. In the following study, we evaluated the suitability of the giant duckweed Spirodela polyrhiza for assessing the toxicity of a municipal landfill leachate and two leachates of copper mining residue. Duckweed static toxicity tests were performed, and frond number was the endpoint used to calculate EC₅₀ values. Symptoms of stress (chlorosis, necrosis, root destruction, and colony breakup) were also recorded. The landfill leachate was toxic with EC_50;96h values ranging from 1.3 to 2.7% leachate (v/v). Toxicity of the copper slag leachate was largely determined by the elution method used. Leachate obtained using conventional German leaching methods (S4-eluate) was not toxic to duckweed, whereas EC₅₀ values for the pH_stat4-eluate ranged from 3.2 to 4.2% leachate (v/v). The results demonstrate the suitability of S. polyrhiza for the testing of unmodified wastewater samples and provide further evidence for the addition of a duckweed toxicity test to the standard tests conducted in Germany.     

The effects of wet and dry seasons on concentrations of solutes and phytoplankton biomass in seven Ethiopian rift-valley lakes

The chemical characteristics and phytoplankton biomass (measured as chlorophyll-a concentrations) of seven lakes and one reservoir in the Ethiopian rift-valley were studied during the wet and dry seasons between 1990 and 2000. Mean concentrations of three major plant nutrients (nitrate-nitrogen, soluble reactive phosphorus, and silicate) increased during the wet seasons in four of the seven lakes, presumably as a result of mixing events and input from runoff. The changes in the major nutrient concentrations in the rest of the lakes were variable, but concentrations were usually higher during the dry seasons, most likely as a response to temporal variation in the phytoplankton biomass. pH measurements of the lakes did not show marked differences between the wet and dry seasons. Salinity (measured as conductivity) and total ions seemed to increase during the wet seasons in some of the lakes, possibly as a result of inflows that might carry high concentrations of solutes due to the heavy rains. Chlorophyll-a concentrations were higher during the dry seasons in most lakes except in three relatively more productive lakes. The results suggest that there could be light limitation in some of the Ethiopian rift-valley lakes, and events associated with the wet and dry seasons could bring about contrasting changes in nutrient levels and phytoplankton biomass in lakes, depending on the physical characteristics of the lakes.     

三峡水库消落区典型草本植物氮、磷养分计量特征

为明确消落区土壤养分对植物生长的影响,通过室内栽培试验,研究三峡库区秭归消落区土壤3种氮磷水平下4种草本植物—鬼针草(Bidens pilosa)、苍耳(Xanthium sibiricum)、水蓼(Polygonum hydropiper)、藜(Chenopodium album)长势及氮、磷计量特征.结果表明,消落区土壤中生长的植物氮含量为7.98~19.4 mg/g,磷含量为0.740~3.880 mg/g,氮磷比为3.48~13.70,判别植物生长受氮限制.外源氮磷的添加促进植物氮、磷含量明显升高,但氮磷比没有明显变化;外源氮磷添加解除植物受氮的限制作用.4种植物对消落区土壤低氮环境具有一定的适应能力.比较消落区土壤中4种植物长势,鬼针草生物量、相对生长率、根茎生物量比最高,氮磷养分丰富对鬼针草生长促进作用最明显,表明鬼针草更易于在氮、磷贫乏的三峡库区消落区形成优势群落.     

Study of Metal Distribution in Raw and Screened Swine Manure

The growth of industrial swine production over the last few years has led to a growth in concern over effluents generated by the activity. Several elements, mainly toxic metals, can be present in swine wastewater and can have a serious environmental impact. It is important, therefore, to know the metal concentration before the discharge of wastewater. In this work the temporal metal distribution in swine manure and its potential reduction using coarse (2 mm) and fine (<0.45 μm) liquid‐solid separation techniques were investigated. In order to do this, different swine manure sample preparation methods for Al, Ba, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sr and Zn determination by Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES) were tested. The acid mixtures used to digest the manure sample significantly affected the metal recovery. Good analyte recoveries were observed with nitric acid/hydrogen peroxide mixtures or nitric acid/perchloric acid mixtures. Sulfuric acid/hydrogen peroxide mixtures produced inconsistent results and poor recoveries, mainly for Ba and Pb. It was observed that metal concentrations in swine manure varied greatly with time, up to one order of magnitude, due to changes in swine production such as feed and animal numbers. Metals concentrations observed in the raw wastewater exceeded Brazilian limits for discharge into water bodies and recommendations for agricultural use. Results obtained from the liquid‐solid separation study showed that metals in the raw swine manure were not removed with coarse screening. However, the major fraction of metals were removed by filtration (0.45 μm), with the exception of Na, K and Sr. Thus, the use of liquid‐solid separation techniques that capture the fine solid fractions (and associated metals) from raw manure can have a favorable impact on the environment and contribute to swine production wastewater treatment.     

Algal Cultivation for Treating Wastewater in African Developing Countries: A Review

The tremendous increase in human population and rapid decline in freshwater resources have necessitated the development of innovative and sustainable wastewater treatment methods. Africa as a developing continent is currently backing on sustainable solutions to tackle impending water resource crisis brought forward by wastewater‐induced environmental pollution and climate change. Microalgae‐based wastewater treatment systems represent an emerging technology that is capable of meeting the new demand for improved wastewater treatment and climate change mitigation strategies in an environmentally friendly manner. This review critically looks at the opportunities of Africa in harnessing and exploiting the potential of microalgae for the treatment of various wastewaters based on their capacity to recycle nutrients and for concurrent production of valuable biomass and several useful metabolites. Wastewaters, if improperly/completely untreated and discharged, simultaneously pollute freshwater sources and present significant health and environmental risks. Nutrients in wastewater can be utilized and recovered in the form of marketable biomass and products when integrated with the cultivation of microalgae. Several valuable bioproducts can be generated from wastewater‐grown microalgal biomass including biofuels, biofertilizers, animal feed, and various bioactive compounds. This biorefinery approach would most certainly improve wastewater treatment process economics, enhancing the technical feasibility of algae‐based wastewater remediation in African countries.     

Rhizofiltration of a Heavy Metal (Lead) Containing Wastewater Using the Wetland Plant Carex pendula

Rhizofiltration is a subset technique of phytoremediation which refers to the approach of using plant biomass for removing contaminants, primarily toxic metals, from polluted water. The effective implementation of this in situ remediation technology requires experimental as well as conceptual insight of plant–water interactions that control the extraction of targeted metal from polluted water resources. Therefore, pot and simulation experiments are used in this study to investigate the rhizofiltration of a lead containing wastewater using plants of Carex pendula, a common wetland plant found in Europe. The metal contaminant extraction along with plant growth and water uptake rates from a wastewater having varying Pb concentration is studied experimentally for 2 wk. The temporal distribution of the metal concentration in the wastewater and the accumulated metal in different compartments of C. pendula at the end are analyzed using atomic absorption spectrometry. Parameters of the metal uptake kinetics are deduced experimentally for predicting the metal removal by root biomass. Further, mass balance equations coupled with the characterized metal uptake kinetics are used for simulating the metal partitioning from the wastewater to its accumulation in the plant biomass. The simulated metal content in wastewater and plant biomass is compared with the observed data showing a good agreement with the later. Results show that C. pendula accumulates considerable amounts of lead, particularly in root biomass, and can be considered for the cleanup of lead contaminated wastewaters in combination with proper biomass disposal alternatives. Also, the findings can be used for performing further non‐hydroponics experiment to mimic the real wetland conditions more closely.     

The nutrient forms,cycling and exchange flux in the sediment and overlying water system in lakes from the middle and lower reaches of Yangtze River

This paper is a review of research works concerning the nutrient transportation, transformation and exchange between water, sediment and biota in the lakes from the middle and lower reaches of the Yangtze River conducted in the context of project entitled “The Processes and Mechanism of Lake Eutrophication in Middle and Lower Reaches of Yangtze River”. All the lakes from this area are shallow lakes. According to the typical lake site research, the lakes from the middle and lower reaches of Yangtze River have a higher baseline of nutrition in the history. Normally the trophic status of these lakes can be categorized into medium-trophic or eutrophic Human activities have been enhanced during the last decades, which speed up the lake eutrophic process. Lake eutrophication control needs to reduce not only the external nutrient inputs from watershed but also the internal loading from the sediments. Investigations revealed that the lake sediments in this area are considerablly high in nutrition in which at most about 30% of phosphorus exists in the form of bio-available in the sediment. The surface sediment will exert great effects on the nutrient exchange between water-sediment interface via adsorption and release of nutrient. The nutrient release from the sediment in these shallow lakes is mainly in two ways, i.e. in the undisturbed condition the nutrient is released through diffusion created by the nutrient gradient from sediment to overlying water; whereas in disturbed condition, the nutrient release is determined by the hydrodynamic forcing intensity and the sediment resuspension. Metallic elements such as the iron, manganese and aluminium and the aerobic-anaerobic ambience will affect the release of nutrients. The disturbed release will increase the total nutrients in the water column significantly in the short period. At the beginning of sediment resuspension, the dissolved nutrient concentration will increase. This increase will be damped if the ferric oxide and aluminium are rich in sediment because of the adsorption and flocculation. This means that the lakes have capability of eliminating the nutrient loadings. Investigations for the lakes from middle and down stream of Yangtze River have suggested that most lakes have the self-cleaning capability. Dredging the control of the internal loading, therefore, is only applicable to the small lakes or undisturbed bays which normally are situated nearby the city or town and rich in organic materials in the sediment. In addition, the strong reduction condition and weak aeration of these lakes and bays make these small lakes and bays release much more bio-available nutrient and without much self-eliminating capability. Moreover, eutrophication induced algal bloom in these lakes will change the pH of water, which further induces the increase in the nutrient release. In turn, the increase in nutrient release promotes the growth of phytoplankton and results in severe algal bloom. For the heavily polluted water, research suggests that the biomass of bacteria and alkaline phosphatase activity will be higher corresponding to the higher concentration of nutrients, which accelerates the nutrient recycling between water, sediment and biota. Quick recycling of nutrient, in turn, promotes the production and biomass growth of microorganism and leads to more severe eutrophication. Further research work should focus on the nutrient transformation mechanism and the effects of microbial loop on the eutrophication.

     

Species diversity of resident green algae slows the establishment and proliferation of the cyanobacterium Microcystis aeruginosa

As harmful algal blooms (HABs) have expanded in size and become more frequent, there have been increased efforts to predict when and why blooms occur, as well as to identify the ecological factors that limit their formation. Here we report the results of a laboratory experiment in which we examined how the establishment and proliferation of Microcystis aeruginosa, a common HAB species, was influenced by competition with resident green algae. We hypothesized that competition with green algae would reduce the final biomass of M. aeruginosa, and that the effects of competition would be most pronounced in communities of high species richness and when nutrients are scarce. We found that competition with green algae did, in fact, consistently reduce the final biomass of M. aeruginosa. The effects of competition were more pronounced in species-rich than in species-poor communities, but this was only true when nutrients were abundant. When nutrients were scarce, resident diversity did not matter because competition with any resident species was sufficient to limit the growth of M. aeruginosa. Our results confirm that biotic interactions with phytoplankton are important in limiting the establishment and proliferation of HAB species like M. aeruginosa. But our work goes on to suggest that, under some nutrient conditions, diverse communities of resident phytoplankton can be more resistant to proliferation of cyanobacteria that can cause HABs.     

Biodegradation by Co‐inoculated Bacteria and Fungi Alleviates Adverse Effects of Red‐S3B on Growth and Nitrogen Uptake of Wheat

Textile wastewater contains huge quantities of nitrogen (N)‐containing azo‐dyes. Irrigation of crops with such wastewater adds toxic dyes into our healthy soils. One of the ways to prevent their entry to soils could be these waters after the dyes' biodegradation. Therefore, the present study was conducted to evaluate the impact of textile dyes on wheat growth, dye degradation efficiency of bacteria‐fungi consortium, and alleviation of dye toxicity in wheat by treatment with microbial consortium. Among dyes, Red‐S3B (3.19% N) was found to be the most toxic to germination and growth of seven‐day‐old wheat seedlings. Shewanella sp. NIAB‐BM15 and Aspergillus terreus NIAB‐FM10 were found to be efficient degraders of Red‐S3B. Their consortium completely decolorized 500 mg L^?1 Red‐S3B within 4 h. Irrigation with Red‐S3B‐contaminated water after treatment with developed consortium increased root length, shoot length, root biomass, and shoot biomass of 30‐day‐old wheat seedlings by 47, 18, 6, and 25%, respectively, than untreated water. Moreover, irrigation after microbial treatment of dye‐contaminated water resulted in 20 and 51% increase in shoot N content and N uptake, respectively, than untreated water. Thus, co‐inoculation of bacteria and fungi could be a useful bioremediation strategy for the treatment of azo‐dye‐polluted water.     

Growth of Plankton (Scenedesmus acutus (Chlorophyceae) and Moina macracopa (Cladocera)) on Domestic Wastewater

The population growth of the freshwater chlorophyte, Scenedesmus acutus and the cladoceran Moina macrocopa cultured in the laboratory and in microcosms of a wastewater treatment plant was studied. S. acutus was cultured in a defined algal medium and mixed with wastewater. On diets of S. acutus cultured using Bold medium or a mixture with wastewater, the peak densities of M. macrocopa were 6–7 ind. mL^?1, while on a diet of algae cultured on wastewater alone the cladoceran density fluctuated around 2 ind. mL^?1. Population growth rates of M. macrocopa, which ranged from 0.3 to 0.4 d^?1, were significantly lower on alga cultured in wastewater alone. The body size structure of M. macrocopa was larger on algae cultured in Bold medium than in wastewater. Peak densities of M. macrocopa were around 700 ind. L^?1 when the organic matter in the containers was supplemented with algae but it reached lower densities (400 ind. L^?1) when cultured on the organic matter in wastewater alone. Our study indicates that the nutrients in the final stages of wastewater treatment can support the growth of both phytoplankton and zooplankton.     

The dose-response relationship between No. 2 fuel oil and the growth of the salt marsh grass,Spartina alterniflora

The effect of No. 2 fuel oil on the biomass production of the salt marsh plant, Spartina alterniflora, was studied in a greenhouse dose-response experiment. S. alterniflora were transplanted into soil with 10 dosage levels of No. 2 fuel oil ranging from 0 to 456 mg g(-1) dry soil. Three months after transplantation, values for plant biomass, stem density, and shoot height decreased significantly with increasing fuel oil level in a dose-response fashion. Evapo-transpiration rates were correlated with the total biomass response. Relative to the control, a significant decrease in total (above- plus below-ground) plant biomass was observed at concentrations above 57 mg g(-1) dry soil. Within the 3-month experimental period, detrimental effects on below-ground biomass accumulation and bioluminescence of the marine bacterium Viberio fisheri in the Microtox Solid Phase Test were observed at oil concentrations >29 mg g(-1) dry soil, suggesting that biological effects of oil within the sediment matrix may be more pronounced than on above-ground biomass, requiring a dosage 228 mg g(-1) dry soil to elicit a significant detrimental effect. Hence, measurements of oil effects with biological end-points based solely on above-ground responses may underestimate the potential impacts of petroleum hydrocarbon spills, especially when the oil has penetrated the soil. While S. alterniflora was proved to be relatively tolerant to the No. 2 fuel oil spills, its effectiveness in phytoremediation operations may be limited at fuel oil levels 228 mg g(-1) dry soil, as both plant growth and microbial activity may be constrained.     

Biomass composition and methods for the determination of metabolic reserve polymers in phototrophic sulfur bacteria

To study nutrient fluxes within aquatic ecosystems, the synthesis of biomass and of various storage polymers has been analysed in samples from a meromictic alpine lake. Methods are described for the quantitative determination of whole cell biomass, glycogen, polyhydroxyalkanoates (PHA) and sulfur. Methods were adapted to conditions present in natural environments and tested with samples from blooms of Chromatiaceae and with corresponding laboratory cultures. Dried bacterioplankton-biomass has been analyzed for sulfur, glycogen and polyhydroxyalkanoates, and after complete oxidation for SO ₄ ^2- , NO ₃ ^- and HPO ₄ ^2- . The average elemental composition of biomass from phototrophic sulfur bacteria, depleted of sulfur and carbon storage compounds, was C₃₈₀H₅₈₀O₁₅₃N₆₇P₃S_2.5M, where M stands for the content of the remaining minor elements. C, H, O, N, P and S accounted for 86.7% of the total dry mass. Storage sulfur in natural populations was equivalent to 2.5% to 13.5% of the dry mass; its content varied by 80% within a diurnal cycle. Glycogen contents fluctuated by approximately 50%; they accounted for 7.5% to 15.2% of the dry cell mass. The total content of reserve materials per cell never exceeded 30% of the dry mass. PHA had not been found in appreciable amounts in cells harvested from the natural lake habitat. Under certain conditions in the laboratoryChromatium okenii could be induced, however, to produce polyhydroxyalkanoates. Sulfur, glycogen and PHA contents of 33, 26 and 11%, respectively, were achieved under laboratory-culture conditions. Cells with up to 60% of their dry mass consisting of reserve materials can be obtained under selected laboratory conditions.     

Use of algal assays to determine the potential for phytoplankton growth / Utilisation des essais d'algues pour la détermination du potentiel pour ce qui regarde la croissance du phytoplancton

Abstract

Algal growth potential is defined as the maximum algal mass (dry weight) that can be produced in a natural water sample under standardized laboratory conditions. Algal growth potential measurements are designed to establish baseline data, growth limiting factors (nutrients), and the influence and source of various growth promoting nutrients and toxicants so as to provide improved means for predicting and controlling excessive algal growth in aquatic habitats. Data can be compared only when the variables which control algal growth are standardized. Algal growth potentials derived in the laboratory may not reflect natural conditions because of insufficient light or temperature, grazing by invertebrates or fish, or the presence of any toxic materials. An understanding of the principle of the test and the factors that affect the expression of algal growth potentials is critical to proper data interpretation.     

The nutrient forms, cycling and exchange flux in the sediment and overlying water system in lakes from the middle and lower reaches of Yangtze River

This paper is a review of research works concerning the nutrient transportation, transformation and exchange between water, sediment and biota in the lakes from the middle and lower reaches of the Yangtze River conducted in the context of project entitled "The Processes and Mechanism of Lake Eutrophication in Middle and Lower Reaches of Yangtze River". All the lakes from this area are shallow lakes. According to the typical lake site research, the lakes from the middle and lower reaches of Yangtze River have a higher baseline of nutrition in the history. Normally the trophic status of these lakes can be categorized into medium-trophic or eutrophic. Human activities have been enhanced during the last decades, which speed up the lake eutrophic process. Lake eutrophication control needs to reduce not only the external nutrient inputs from watershed but also the internal loading from the sediments. Investigations revealed that the lake sediments in this area are considerablly high in nutrition in which at most about 30% of phosphorus exists in the form of bio-available in the sediment. The surface sediment will exert great effects on the nutrient exchange between water-sediment interface via adsorption and release of nutrient. The nutrient release from the sediment in these shallow lakes is mainly in two ways, i.e. in the undisturbed condition the nutrient is released through diffusion created by the nutrient gradient from sediment to overlying water; whereas in disturbed condition, the nutrient release is determined by the hydrodynamic forcing intensity and the sediment resuspension. Metallic elements such as the iron, manganese and aluminium and the aerobic-anaerobic ambience will affect the release of nutrients. The disturbed release will increase the total nutrients in the water column significantly in the short period. At the beginning of sediment resuspension, the dissolved nutrient concentration will increase. This increase will be damped if the ferric oxide and aluminium are rich in sediment because of the adsorption and flocculation. This means that the lakes have capability of eliminating the nutrient loadings. Investigations for the lakes from middle and down stream of Yangtze River have suggested that most lakes have the self-cleaning capability. Dredging the control of the internal loading, therefore, is only applicable to the small lakes or undisturbed bays which normally are situated nearby the city or town and rich in organic materials in the sediment. In addition, the strong reduction condition and weak aeration of these lakes and bays make these small lakes and bays release much more bio-available nutrient and without much self-eliminating capability. Moreover, eutrophication induced algal bloom in these lakes will change the pH of water, which further induces the increase in the nutrient release. In turn, the increase in nutrient release promotes the growth of phytoplankton and results in severe algal bloom. For the heavily polluted water, research suggests that the biomass of bacteria and alkaline phosphatase activity will be higher corresponding to the higher concentration of nutrients, which accelerates the nutrient recycling between water, sediment and biota. Quick recycling of nutrient, in turn, promotes the production and biomass growth of microorganism and leads to more severe eutrophication. Further research work should focus on the nutrient transformation mechanism and the effects of microbial loop on the eutrophication.     

An Empirical Evaluation of the Influence of Ethanol on Natural Attenuation of Gasoline Constituents

Since the 1990s, questions have arisen as to whether the release of ethanol‐blended fuel will inhibit natural attenuation of other gasoline constituents in groundwater. This study evaluated the hypothesis that ethanol affects hydrocarbon attenuation and whether the use of ethanol‐blended fuel alters the applicability of monitored natural attenuation (MNA) as an approach for managing risks at fuel‐release sites. Groundwater data from California's GeoTracker database were used to compare attenuation of benzene, toluene, methyl tert‐butyl ether (MTBE), and tert‐butyl alcohol (TBA) at sites with and without detections of ethanol. Excel‐based tools were developed to conduct attenuation evaluations on thousands of wells simultaneously. Ethanol was detected at least once in 4.5% of the wells and 0.6% of the samples of which it was analyzed. The distribution of Mann‐Kendall concentration trend analysis results and first‐order attenuation rates were essentially the same at sites with or without ethanol detections. Median plume lengths were shorter at sites where ethanol had not been detected compared to sites where ethanol was detected (36 vs. 43 m for benzene; 36 vs. 42 m for toluene; 43 vs. 52 m for MTBE; and 44 vs. 59 m for TBA). However, the distribution of plume lengths was similar irrespective of ethanol concentrations, suggesting other factors may influence plume elongation. Finally, while anaerobic ethanol degradation can result in methane generation, the distributions of methane concentrations were the same at sites with and without ethanol detections. These results suggest that the use of ethanol‐blended fuel should not limit the application of MNA at most biodegrading fuel‐release sites.     

Vermicomposting: An Eco‐Friendly Option for Fermentation and Dye Decolourization Waste Disposal

By‐products of various industrial fermentations can be good adsorbents for removing hazardous dyes from wastewater. However, after biosorption, regeneration of biomass is essential to minimize the solid waste generation or else the dye laden biomass should be suitably disposed off. In the present work, experiments were conducted on the Acid Navy Blue and Methylene Blue dyes which were biosorbed to the fungal biomass (strain closely related to Aspergillus lentulus) produced on corncob as the substrate through solid state fermentation. In order to dispose the dye laden biomass, it was vermicomposted along with cow dung (CD) employing Eisenia fetida. Results indicated that the dye laden biomass was not lethal toward the earthworms as no mortality was observed. However, as compared with control experiments (where dye laden biomass was absent), the reproductive potential of the earthworms was affected. Nevertheless, further investigations on optimization of biomass and CD ratios can facilitate vermicomposting as a potential route for disposing dye laden biomass.