Engineered nanoparticles in wastewater and wastewater sludge – Evidence and impacts

Nanotechnology has widespread application in agricultural, environmental and industrial sectors ranging from fabrication of molecular assemblies to microbial array chips. Despite the booming application of nanotechnology, there have been serious implications which are coming into light in the recent years within different environmental compartments, namely air, water and soil and its likely impact on the human health. Health and environmental effects of common metals and materials are well-known, however, when the metals and materials take the form of nanoparticles – consequential hazards based on shape and size are yet to be explored. The nanoparticles released from different nanomaterials used in our household and industrial commodities find their way through waste disposal routes into the wastewater treatment facilities and end up in wastewater sludge. Further escape of these nanoparticles into the effluent will contaminate the aquatic and soil environment. Hence, an understanding of the presence, behavior and impact of these nanoparticles in wastewater and wastewater sludge is necessary and timely. Despite the lack of sufficient literature, the present review attempts to link various compartmentalization aspects of the nanoparticles, their physical properties and toxicity in wastewater and wastewater sludge through simile drawn from other environmental streams.     

Biodegradation of polycyclic aromatic hydrocarbons (PAHs) by fungal enzymes: A review

Polycyclic aromatic hydrocarbons (PAHs) are a large group of chemicals. They represent an important concern due to their widespread distribution in the environment, their resistance to biodegradation, their potential to bioaccumulate and their harmful effects. Several pilot treatments have been implemented to prevent economic consequences and deterioration of soil and water quality. As a promising option, fungal enzymes are regarded as a powerful choice for degradation of PAHs. Phanerochaete chrysosporium, Pleurotus ostreatus and Bjerkandera adusta are most commonly used for the degradation of such compounds due to their production of ligninolytic enzymes such as lignin peroxidase, manganese peroxidase and laccase. The rate of biodegradation depends on many culture conditions, such as temperature, oxygen, accessibility of nutrients and agitated or shallow culture. Moreover, the addition of biosurfactants can strongly modify the enzyme activity. The removal of PAHs is dependent on the ionization potential. The study of the kinetics is not completely comprehended, and it becomes morem hallenging when fungi are applied for bioremediation. Degradation studies in soil are much more complicated than liquid cultures because of the heterogeneity of soil, thus, many factors should be considered when studying soil bioremediation, such as desorption and bioavailability of PAHs. Different degradation pathways can be suggested. The peroxidases are heme-containing enzymes having common catalytic cycles. One molecule of hydrogen peroxide oxidizes the resting enzyme withdrawing two electrons. Subsequently, the peroxidase is reduced back in two steps of one electron oxidation. Laccases are copper-containing oxidases. They reduce molecular oxygen to water and oxidize phenolic compounds.     

Fate and transport of fragrance materials in principal environmental sinks

Fragrance materials are widely present in the environment, such as air, water, and soil. Concerns have been raised due to the increasing utilization and suspected impact on human health. The bioaccumulating property is considered as one of the causes of the toxicity to human beings. The removal of fragrance materials from environmental sinks has not been paid enough attention due to the lack of regulation and research on their toxicity. This paper provides systematic information on how fragrance materials are transferred to the environment, how do they affect human lives, and what is their fate in water, wastewater, wastewater sludge, and soil.     

Investigation on removal pathways of Di 2-ethyl hexyl phthalate from synthetic municipal wastewater using a submerged membrane bioreactor

Highly hydrophobic Di 2-ethyl hexyl phthalate (DEHP) is one of the most prevalent plasticizers in wastewaters. Since its half-life in biological treatment is around 25 days, it can be used as an efficiency indicator of wastewater treatment plant for the removal of hydrophobic emerging contaminants. In this study, the performance of submerged membrane bioreactor was monitored to understand the effect of DEHP on the growth of aerobic microorganisms. The data showed that the chemical oxygen demand (COD) and ammonia concentration were detected below 10 and 1.0 mg/L, respectively for operating conditions of hydraulic retention time (HRT) = 4 and 6 hr, sludge retention time (SRT) = 140 day and sludge concentration between 11.5 and 15.8 g volatile solid (VS)/L. The removal efficiency of DEHP under these conditions was higher and ranged between 91% and 98%. Results also showed that the removal efficiency of DEHP in biological treatment depended on the concentration of sludge, as adsorption is the main mechanism of its removal. For the submerged membrane bioreactor, the pore size is the pivotal factor for DEHP removal, since it determines the amount of soluble microbial products coming out of the process. Highly assimilated microorganisms increase the biodegradation rate, as 74% of inlet DEHP was biodegraded; however, the concentration of DEHP inside sludge was beyond the discharge limit. Understanding the fate of DEHP in membrane bioreactor, which is one of the most promising and futuristic treatment process could provide replacement for conventional processes to satisfy the future stricter regulations on emerging contaminants.     

Unwanted metals and hydrophobic contaminants in bioreactor effluents are associated with the presence of humic substances

Biological treatment of landfill leachate is challenging due to the presence of complex compounds. Here, we treated an old landfill leachate using a membrane bioreactor under the following conditions: 24 h for hydraulic retention, 65 days of sludge retention and an average organic load rate of 1.71 ± 0.16 g/L/day. We observed a high removal of ammonia, phosphorous and some metals. However, removal of organic carbon was incomplete. Despite a major removal of suspended solids, hydrophobic and volatile hydrophilic compounds, high concentration of fulvic acid and hydrophilic contaminants was found in the effluent. Overally, we demonstrate that the presence of humic substances in the effluent is associated with the detection of arsenic, copper and chromium and di(2-ethylhexyl) phthalate.     

Corrosion and stability study of Bacillus thuringiensis var. kurstaki starch industry wastewater-derived biopesticide formulation

Biopesticides are usually sprayed on forests by using planes made up of aluminum alloy. Bioval derived from starch industry wastewater (SIW) in suspension form was developed as stable anticorrosive biopesticide formulation. In this context, various anticorrosion agents such as activated charcoal, glycerin, ethylene glycol, phytic acid, castor oil and potassium silicate were tested as anticorrosive agents. There was no corrosion found in Bioval formulation where potassium silicate (0.5% w/v) was added and compared with Foray 76 B, as an industrial standard, when stored over 6 months. In relation to other parameters, the anticorrosion formulation of Bioval+buffer+KSi reported excellent zeta potential (?33.19 ± 4 mV) and the viscosity (319.13 ± 32 mPa.s) proving it's stability over 6 months, compared to the standard biopesticide Foray 76 B (?36.62 ± 4 mV potential zeta, pH 4.14 ± 0.1 and 206 ± 21 mPa.s viscosity). Metal analysis of the different biopesticides showed that Bioval+buffer+KSi has no corrosion (5.11 ± 0.5 mg kg^?1 of Al and 13.53 ± 1.5 mg kg^?1 of Fe) on the aluminum alloy due to the contribution of sodium acetate buffer at pH 5. The bioassays reported excellent results for Bioval+Buffer+KSi (2.95 ± 0.3 × 10⁹ CFU mL^?1 spores and 26.6 ± 2.7 × 10⁹ IU L^?1 Tx) compared with initial Bioval (2.46 ± 0.3 × 10⁹ CFU mL^?1 spores and 23.09 ± 3 × 10⁹ IU L^?1 Tx) and Foray 76 B (2.3 ± 0.2 × 10⁹ CFU mL^?1 spores and 19.950 ± 2.1 UI L^?1 Tx) which was due to the break-up of the external chitinous membrane due to abrasive action of potassium silicate after ingestion by insects. The contribution of sodium acetate buffer and potassium silicate (0.5% and at pH = 5) as anticorrosion agent in the Bioval allowed production of an efficient biopesticide with a reduced viscosity and favorable pH as compared to Foray 76 B which enhanced the entomotoxic potential against spruce budworm (SB) larvae (Lepidoptera: Choristoneura fumiferana).     

Areawide Trace Metal Concentrations Measured by Multielement Neutron Activation Analysis

A suite of 24 hour high volume air particulate samples, collected June 11–12,1969, at 25 locations in the Northwest Indiana area, has been analyzed by nondestructive neutron activation analysis for 30 trace elements. The use of Ge(Li) gamma-ray spectrometry and computer assisted data reduction, combined with 2-4 replications of each analysis, yielded precise results which allowed a study of the geographical distribution patterns of the elements. Some elements, such as Na, K, Ti, Al, Sm, and Eu, show only minor concentration variations over the area,while others, such as Cu, W, Cr, Zn, Sb, Ga, Br, Ag, Fe, and Ce, show large variations, indicative of important local sources. Similar distribution patterns and high correlation coefficients suggest common sources for several elements. The variations of most heavy elements significantly exceed previously reported variations of total particulate, indicating the latter to be an unsatisfactory guide for elemental distribution, especially near pollution sources. Three representative locations for measurement of elemental abundances in the area are suggested. The influence of meteorological conditions and the potential Lake Michigan pollution hazard are discussed     

Rheological profile of diets produced using agro-industrial wastes for rearing codling moth larvae for baculovirus biopesticides

A rheological study of diets using the agro-industrial wastes (brewery wastewater and pomace waste) was carried out in order to obtain a diet most adapted to supply nutrients for growth of codling moth (CM) larvae. Nutritive capacity (g/L) of brewery wastewater (BWW) (25.5 ± 5.5 carbohydrates; 16.9 ± 2.1 proteins; 6 ± 1.6 lipids) and pomace waste (POM) (22.0 ± 0.03 carbohydrates; 11.3 ± 1.3 proteins; 2 ± 0.2 lipids) were essential and important as replacement or in association with other ingredients [soya flour (SF), wheat germ (WG), yeast extract (YE)] of the standard diet for the breeding of codling moth larvae. These diet additives also contributed to the preservation of texture and nutritive content of larvae diet. The eggs and CM larvae were grown on alternate diets under industrial conditions (16:8 h photoperiod; 25 ± 1 °C and 50 ± 0.5 % of humidity). The higher assimilation of nutrients of the diets in BWW and control diet was observed by calculating the rate of hatching of eggs (0.48 to 0.71); larvae growth (0.23 to 0.4) and fertility (1.33 to 3 for control diet). The excellent growth and fertility rates of codling moth larvae were attributed to variations in viscosity (varying from 50 to 266 mPa.s?1), particle size (varying 24.3 μm in 88.05 μm with regard to 110 μm the control diet) and total solids (145.88 g/L POM + YE; 162.08 g/L BWW + YE; 162.2 g/L POM + WG; 173 g/L control; 174.3 g/L BWW + WG) diets. Lower viscosity favored improved diet due to ease of assimilation of nutrients. Thus, rheology is an important parameter during preparation of diets for growth of codling moth larvae as it will dictate the nutrient assimilation which is an important parameter of larvae growth.