Mesophilic anaerobic digestion of waste activated sludge in an intermittent mixing reactor: Effect of hydraulic retention time and organic loading rate.

An anaerobic digester was operated at mesophilic temperature and with intermittent mixing conditions to treat waste activated sludge. The organic loading rate (OLR) was increased by decreasing the hydraulic retention time (HRT), and the effect on process performance, digestate characteristics and inactivation of pathogens was investigated. The removal efficiency of total volatile solids (TVS) was also measured by biogas formation. The HRT varied from 50 to 7 days, corresponding to OLR from 0.38 to 2.31 kgTVS.m-3.d-1. The acidity/alkalinity ratio remained within stable limits (lower than 0.6) at 50-, 25- and 17-day HRT; due to an imbalance between the production and consumption of volatile fatty acids, the ratio increased to 0.7 ± 0.2 at HRT of 9 days and 7 days. The highest TVS removal efficiencies were 16, 12 and 9%, which were obtained at 50-, 25- and 17 day-HRT, respectively. Intermittent mixing provided solids sedimentation greater than 30% for almost all HRT tested. The highest methane yields (0.10-0.05 m3.kgTVSfed-1.d-1) were obtained when the reactor was operated at a higher HRT (50-17 days). At lower HRT, methanogenic reactions were likely limited. Zinc and copper were the main heavy metals found in the digestate, while the most probable number (MPN) of coliform bacteria remained below 106 MPN.g TVS-1. Neither Salmonella nor viable Ascaris eggs were found in the digestate. In general, increasing the OLR by decreasing the HRT to 17 days under intermittent mixing conditions provided an attractive alternative to treat sewage sludge despite some limitations due to biogas and methane yields.

Reproductive innovation and the recognition of a new genus within the Polystomatidae (Monogenea) infecting chelonian vertebrates.

Polystomatid monogeneans have a wide diversity of life cycles correlated with the varied ecology and behaviour of their aquatic vertebrate hosts. Typically, transmission involves a swimming infective larva but most hosts are amphibious and invasion is interrupted when hosts leave water. A key life cycle adaptation involves a uterus that, in the most specialised cases, may contain several hundred fully-developed larvae prepared for instant host-to-host transmission. By contrast, one subfamily of the Polystomatidae - the Polystomoidinae, specific to chelonians (freshwater turtles) - has a simplified reproductive system without a uterus. Recently, Polystomoides nelsoni Du Preez et Van Rooyen, 2015 has been described with a uterus containing multiple eggs. The present study explores the exceptional interest of this parasite - for the functional biology of egg production, for the evolution of a reproductive system unique amongst ca 60 species in the subfamily, and for systematic relationships. A new genus is proposed, Uteropolystomoides gen. n., separate from the four currently-recognised genera Polystomoides Ward, 1917, Uropolystomoides Tinsley et Tinsley, 2016, Neopolystoma Price, 1939 and Polystomoidella Price, 1939 which lack a uterus. In addition, U. nelsoni (Du Preez et Van Rooyen, 2015) comb. n. has a suite of distinctive copulatory stuctures: a massive genital bulb with an exceptionally large number of very long genital spines and hyper-development of the vaginal openings. These characters set U. nelsoni apart from all other polystomoidines worldwide except Polystomoides multifalx Stunkard, 1924 and P. stunkardi Harwood, 1931. Missing data for these latter species preclude definitive assessment of inter-relationships but the distinguishing characters of U. nelsoni, especially the unique occurrence of the uterus, suggest a novel evolutionary pathway isolated from other lineages of polystomatids infecting chelonians.

V-shaped pits in regions of ancient Baekje kingdom paleoparasitologically confirmed as likely human-waste reservoirs.

In a paleo-parasitological analysis of soil samples obtained from V-shaped pits dating to the ancient Baekje period in Korean history, we discovered Ascaris lumbricoides, Trichuris trichiura, and Clonorchis sinensis eggs. In light of the samples' seriously contaminated state, the V-shaped pits might have served as toilets, cesspits, or dung heaps. For a long period of time, researchers scouring archaeological sites in Korea have had difficulties locating such structures. In this context then, the present report is unique because similar kind of the ancient ruins must become an ideal resource for successful sampling in our forthcoming paleoparasitological studies.

Helminth Eggs as a Magnetic Biomaterial: Introducing a Recognition Probe.

Parasitic helminths, despite their known negative impact (biomaterial) on human health and animal production, have fascinating features. In this study, we find fantastic magnetic properties in several forms: inductor [between 20.10 and 58.85 (±2.50) H], source of detectable electrical voltage [from +0.5 to 7.3 (±0.1) V, vs. the ground, GND, measured by an AVO meter] and different inductor magnitude [between 3.33 and 41.23 (±0.76)] µH, detected by electrochemical impedance spectroscopy as well as frequency scannable electromagnetic wave horn) in several frequencies (including 100, 120, Hz, and 1, 10, 100 kHz) in "Fasciola hepatica", "Parascaris equorum" (with and without larvae), "Dicrocoelium dendriticum," "Taenia multiceps", and "Moniezia expansa" eggs. This claim is attributed to some surprising characteristics, including superior inductance and intrinsic magnetic susceptibility. This feature along with a close relationship to helminth egg structure, is a novel probe with acceptable reproducibility (RSD > 8.0%) and high enough trustworthiness for adequate differentiation in their magnitudes, relatively. These traits were measured by the "Single Cell Rrecording" methodology using a three-microelectrode system, implanted to each egg at the Giga ohm sealed condition (6.08 ± 0.22 GΩ cm-1, n = 5). The reliability of these results was further confirmed using multiple calibrated instruments such as a high-resolution inductance analyzer, LCR meter, impedance spectrometer, potentiometer, and an anomalous Hall effect (Magnetic field density) sensor. In addition, the critical role played (Synergistic Effect) by water-like molecules as the intermediate medium, besides the partial influence of other compounds such as dissolved oxygen, are investigated qualitatively, and specific relation between these molecules and magnetic field creation in helminth eggs was proved. These intrinsic characteristics would provide novel facilitators for efficient arriving at the researchable bio-based magnetic biomaterials, besides innovative and real-time identification probes in the "Parasitology" fields.

Supercapacitance/Resistance Behaviors of Helminth Eggs as Reliable Recognition and Direct Differentiation Probe.

Parasitic helminths are usually known as undesired pathogens, causing various diseases in both human and animal species. In this study, we explore supercapacitance/resistance behaviors as a novel probe for rapid identification and direct differentiation of Fasciola hepatica, Parascaris equorum (with and without larvae), Dicrocoelium dendriticum, Taenia multiceps, and Moniezia expansa eggs. This claim is attributed to some characteristics, such as grave supercapacitance/area, high-energy storage/area, large power/egg, huge permittivity, and great electrical break-down potential, respectively (Fasciola hepatica: 2,158, 0.485, 2.7 × 10-3, 267, 52.6, Parascaris equorum without larvae: 2,825, 0.574, 3.0 × 10-3, 351, 68.4, Parascaris equorum with larvae: 4,519, 0.716, 2.4 × 10-3, 1.96, 97.6, Dicrocoelium dendriticum: 1,581, 0.219, 2.8 × 10-3, 1.96, 48.8, Moniezia expansa: 714, 0.149, 2.2 × 10-3, 0.88, 35.2, Taenia multiceps: 3,738, 0.619, 4.7 × 10-3, 4.63, 84.4), and durable capacitance up to at least 15,000 sequential cycles at different scan rates (between 2.0 × 10-4 and 120.0 V s-1) as well as highly differentiated resistance between 400 and 600 Ω. These traits are measured by the "Blind Patch-Clamp" method, at the giga ohm sealed condition (6.18 ± 0.12 GΩ cm-1, n = 5). Significant detection ranges are detected for each capacitance and resistance with gradient limits as large as at least 880 to 1,000 mF and 400 to 600 Ω depending on the type of helminth egg. The effect of water in the structure of helminth eggs has also been investigated with acceptable reproducibility (RSD 7%-10%, n = 5). These intrinsic characteristics would provide novel facilitators for direct helminth egg identification in comparison with several methods, such as ELISA, PCR, and microscopic methods.

Inactivation of helminth eggs in an electro-Fenton reactor: Towards full electrochemical disinfection of human waste using activated carbon.

The disinfection of helminth eggs and Escherichia coli contaminated aqueous solutions, was studied using an electro-Fenton reactor equipped with a polarized activated carbon (AC) packed bed and two chambers loaded with cation exchange resins. Experiments using different arrangements and operation conditions, revealed that effective elimination of Escherichia coli takes place in all electrochemical disinfection tests. For the more resistant helminth eggs however, adsorption, electro-oxidation and electro-Fenton experiments showed retention within the reactor and pathogen inactivation values of 0, 16, and 25%, respectively. Using helminth eggs concentration data in different sections of the reactor, optical microscopy analysis and an exploratory computer simulation, differences in the disinfection performance were explained and new recirculation and flow direction and polarization switching operation schemes were defined. The corresponding experiments revealed that the effective coupling between adsorption and electro-Fenton phenomena, all along the AC packed bed compartment, results in 100% inactivation of helminth eggs.

Modified flotation method, an effective technique for recovering helminth eggs in soil.

There is no established method for recovering helminth eggs in soil has yet to be established. Here, we introduce a novel method for their recovery based on a centrifugal flotation approach using a sucrose solution with a specific gravity of 1.20, with a coverslip being placed on the sucrose-filled centrifuge tube during centrifugation. The recovery of zoonotic Toxocara eggs from soil was more effective when this method was compared with the traditional flotation method. This method detects not only zoonotic Toxocara eggs, but Ascaris lumbricoides, Trichuris trichiura, and other human parasite eggs also, indicating that it can be used for epidemiological studies both in developed and developing countries.

Detection of parasitic particles in domestic and urban wastewaters and assessment of removal efficiency of treatment plants in Tehran, Iran.

BACKGROUND: In recent years, decreasing annual rainfalls in some countries and population growth have led to a shortage of freshwater resources. Thus, recycled wastewaters has been suggested for agricultural activities. Contamination of wastewaters with pathogens is a major concern for the use of these waters. This study aimed to (i) investigate the occurrence of helminth eggs and protozoan (oo)cysts in human and livestock wastewaters, and (ii) evaluate the parasite removal efficiencies of urban and slaughterhouse treatment plants in Tehran province, Iran. One hundred and eight samples were collected from five urban and domestic wastewater treatment plants in Iran. Wastewater samples were concentrated by centrifugal-concentration and filtration methods. RESULTS: The quantity of helminths egg and protozoa (oo)cyst per liter of urban raw wastewater ranged from 1.2 × 10(1) to 2.9 × 10(1) and from 9.6 × 10(2) to 1.9 × 10(3), respectively. The number of eggs and (oo)cysts per liter of animal raw wastewater ranged from 1.6 × 10(3) to 4.9 × 10(3) and 3.1 × 10(4) to 6.0 × 10(4), respectively. The helminths and protozoa identified in urban treatment plants included hookworms, Hymenolepis and Rhabditis (or probably Strongyloides), Entamoeba, Isospora, Giardia, Chilomastix and Cryptosporidium, while in slaughterhouses Trichuris, Trichostrongylus, Moniezia, Dicrocoelium, Fasciola, Entamoeba, Cryptosporidium, Eimeria and Giardia were isolated. The overall removal efficiency of eggs and (oo)cysts in the treatment plants ranged from 94.8 to 95.7% and from 79.3 to 85.8%, respectively. CONCLUSION: The study results revealed that the efficacy of removal of nematode eggs, and not protozoan (oo)cysts, in urban wastewater treatment plants, is in compliance with the WHO parasitological guideline (<1 nematode per liter) required for unrestricted irrigation.

Modeling the inactivation of ascaris eggs as a function of ammonia concentration and temperature.

Ammonia sanitization is a promising technology for sanitizing human excreta intended for use as a fertilizer in agriculture. Ascaris eggs are the most persistent pathogens regarding ammonia inactivation and are commonly present in fecal sludge in low- and middle-income countries. In this study, a model for predicting ammonia inactivation of ascaris eggs was developed. Data from four previous studies were compiled and analyzed statistically, and a mathematical model for the treatment time required for inactivation was created. The inactivation rate increased with NH3 activity to the power of 0.7. The required treatment time was found to decrease 10-fold for each 16 °C temperature increase. Dry matter (DM) content and pH had no direct effect on inactivation, but had an indirect effect due to their impact on NH3 activity, which was estimated using the Pitzer approach. An additional model giving an approximation of Pitzer NH3 activity but based on the Emerson approach, DM content and total ammonia (NHTot) was also developed. The treatment time required for different log10 reductions of ascaris egg viability can thus easily be estimated by the model as a function of NH3 activity and temperature. The impact on treatment time by different treatment options can then be theoretically evaluated, promoting improvements of the treatment e.g. by adding urea or alkaline agents, or increasing the temperature by solar heating.