Selective reduction of the pathogenic load of cow manure in an industrial-scale continuous-feeding vermireactor

Vermicomposting is a suitable technology for processing different wastes, to produce a valuable end product (vermicompost). However, the pathogenic load of the waste must be greatly reduced in order to prevent risks to human health. Although Eisenia andrei may reduce the levels of several pathogens, the feasibility of vermicomposting, with regard to pathogen reduction, has not been tested on an industrial scale. This work studied whether vermicomposting in a continuous feeding vermireactor, is able to reduce the pathogenic load of cow manure. The effect of E. andrei on pathogens depended on the type of pathogen; thus, levels of Clostridium, total coliforms and Enterobacteria were not modified, but levels of faecal enterococci, faecal coliforms and Escherichia coli were reduced to acceptable levels. Pathogens could have maintained their levels in continuous feeding vermireactors, as fresh layers of manure are added to the top, which allows the vertical spread of pathogens through leaching.     

Composting-vermicomposting of leaf litter ensuing from the trees of mango (Mangifera indica)

Litter of the mango (Mangifera indica) tree leaves was composted and then converted into vermicast by the action of the earthworm Eudrilus eugeniae Kinberg. After over nine months of continuous operation the vermireactors with 62.5 animals l(-1) generated approximately 13.6g vermicast per litre of reactor volume (l) per day (d) whereas the reactors with 75 animals l(-1) produced approximately 14.9 g vermicast l(-1) d(-1). This difference in performance of the reactors operating in duplicate at the two different earthworm densities was statistically significant (> or = 90% confidence level) for most of the nine-month span. The animals grew well in all reactors, increasing their zoomass by approximately 103% and producing approximately 157 offspring. Not a single of the 1100 animals died during the first four months. In the subsequent five months a total of 122 worms died, representing a loss of approximately 2% per month. We attribute this to the normal process of ageing. The ability of the earthworms to survive, grow and breed in the vermireactors fed with composted mango tree leaves, and a rising trend in vermicast output inspite of the death of a few worms after four months of reactor operation, indicate the sustainability of this type of vermireactors. The studies also indicate that even better vermireactor efficiency may be possible by modifying the reactor geometry. Studies on changes in C:N ratio during composting and vermicomposting revealed that whereas composting helped in lowering the ratio due to loss of carbon in bacterial metabolism, vermicomposting had no such effect on the ratio.     

The use of chemically modified and unmodified cassava waste for the removal of Cd, Cu and Zn ions from aqueous solution

The use of different chemically modified cassava waste biomass for the enhancement of the adsorption of three metal ions Cd, Cu and Zn from aqueous solution is reported in this paper. Treating with different concentrations of thioglycollic acid modified the cassava waste biomass.

The sorption rates of the three metals were 0.2303 min⁻¹ (Cd²⁺), 0.0051 min⁻¹ (Cu²⁺), 0.0040 min⁻¹ (Zn²⁺) and 0.109 min⁻¹ (Cd²⁺), 0.0069 min⁻¹ (Cu²⁺), 0.0367 min⁻¹ (Zn²⁺) for 0.5 and 1.00 M chemically modified levels, respectively. The adsorption rates were quite rapid and within 20–30 min of mixing, about 60–80% of these ions were removed from the solutions by the biomass and that chemically modifying the binding groups in the biomass enhanced its adsorption capacity towards the three metals. The results further showed that increased concentration of modifying reagent led to increased incorporation, or availability of more binding groups, in the biomass matrix, resulting in improved adsorptivity of the cassava waste biomass. The binding capacity study showed that the cassava waste, which is a serious environmental nuisance, due to foul odour released during decomposition, has the ability to adsorb trace metals from solutions.     

Vertical seed dispersal by earthworms: a quantitative approach

Earthworms are supposed to play an important role in the dynamics of the soil seed bank, however, experimental evidence and quantitative data are scarce To evaluate the impact of the earthworm species Lumbricus terrains L on the vertical transport of seeds in the soil, laboratory experiments have been earned out Moreover, the worm casts produced and their seed content have been quantified in two chalk grassland sites during one year
The experiment on seed transport has been earned out in cylinders with controlled numbers of worms and seeds at different depths in stenlized soil Seeds used in this experiment proved to be eaten by the earthworms in preceding palatability tests A significant translocation of the seeds in the cylinders with earthworms was recorded after an eight-week period In spring earthworm activity was mainly found m the upper soil layers in the cylinders, whereas in summer the activity was spread over a larger vertical distance The amount of worm casts collected on permanently marked plots in two different chalk grasslands was very high a minimal quantity of c 750 g nr² of worm casts were produced yearly The number of germinative seeds brought to the soil surface by worm casts was at least 60-100 nr² each year This means that earthworm activity has a substantial impact on the soil seed bank dynamics and hence on the possibility of plant recruitment in this species-nch ecosystem     

Towards maximising output from vermireactors fed with cowdung spiked paper waste

Paper waste, spiked with varying proportions of cowdung, was vermicomposted in 'low-rate' and 'high-rate' reactors. The former type of reactors had earthworm populations and feed loading rates similar to ones recommended by previous workers. The 'high-rate' reactors were operated with 12.5 times higher earthworm densities and feed loading rates. All the reactors were studied for six months to assess the vermicast output, survivability, growth and reproduction of the earthworms hence the sustainability of the reactors--for long-term, continuous operation. The studies revealed the viability of the high-rate vermireactor concept. The high-rate reactors consistently produced over 6.5 times more castings per unit digester volume with no adverse effect on the earthworm population, as reflected by (a) absence of mortality, (b) consistent growth in worm zoomass, and (c) normal rate of reproduction. The studies also revealed that an increase in the cowdung fraction in the feed from 14.3% to 20% (4:1 paper:cowdung blends to 6:1 blends) had little positive impact on the vermicast output or earthworm health. This indicated that spiking of paper feed with approximately 14% cowdung, or perhaps an even smaller fraction, might be adequate to support earthworms in the paper-fed vermireactors.     

Development of a water hyacinth based vermireactor using an epigeic earthworm Eisenia foetida

The aim of this work was to investigate the potential of water hyacinth (WH) spiked with cow dung (CD) into vermicompost. Five vermireactors containing WH and CD in different ratios, were run under laboratory conditions for 147 days. The maximum worm growth was recorded in CD alone. Worms grew and reproduced favourably in 25% WH+75% CD feed mixture. Greater proportion of WH in feed mixture significantly affected the biomass gain, hatchling numbers and numbers of cocoons produced during experiments. In all the vermireactors, there was significant decrease in pH, TOC and C:N ratio, but increase in TKN, TK and TAP at the end. The heavy metals content in the vermicomposts was lower than initial feed mixtures. The results indicated that WH could be potentially useful as raw substrate in vermicomposting if mixed with up to 25% in cow dung (on dry weight basis).     

Identification of by-products in hydrogen producing bacteria; Rhodobacter sphaeroides O.U. 001 grown in the waste water of a sugar refinery

Rhodobacter sphaeroides O.U. 001 is able to produce hydrogen anaerobically upon illumination. The cells were screened for the presence of valuable by-products such as poly-β-hydroxy (PHB) butyric acid aiming to improve the feasibility of the system. Also waste water from a sugar refinery was used for bacterial growth to further increase the feasibility. Under aerobic conditions the standard growth media containing -malic acid and sodium glutamate in 7.5/10 and 15/2 molar ratios and a medium containing 30% waste water from sugar refinery were used. In this case the maximum concentration of PHB produced were approximately 0.2 g l⁻¹ in both of the standard media whereas it was 0.3 g l⁻¹ in medium containing 30% waste water. By using the medium containing 30% waste water, PHB and hydrogen productions were determined under anaerobic conditions. The maximum concentration of PHB produced was around 0.5 g l⁻¹ and the amount of gas collected was 35 ml in 108 h. From these results it can be concluded that PHB can be collected during hydrogen production. The use of waste water from sugar refinery increased the yield.     

Vermicomposting in the management of pig-waste in Hong Kong

The treatment and disposal of pig-waste in Hong Kong has received much attention in recent years but, following any of the presently used treatment processes, solids remain to be further stabilized. Vermicomposting is a waste stabilization technique which converts waste into potentially recyclable materials such as worm protein and worm casts. The earthworm, Pheretima asiatica, can stabilize most of the solids arising from the treatment of pig-waste, including raw pig manure, suggesting that vermicomposting has a high potential as a unit process in the management of pig-waste in Hong Kong.S.H. Wong is with the Environmental Protection Department, Hong Kong; and D.A. Griffiths is with the Department of Botany, University of Hong Kong, Hong Kong.     

Anaerobic fluidised bed for the purification of effluents from chemical and mechanical pulping

Anaerobic treatment has seldom been used for wastewaters from the pulp and paper industry and other branches of the chemical industry. Escape of volatile pollutants to the atmosphere, which always occurs during aerobic treatment, is avoided, and much less sludge is being produced than in an aerobic process. The greatest obstacle for using anaerobic treatment in the pulp and paper industry is the large wastewater volume, which necessitates short hydraulic detention times, because the treatment is to occur in an enclosed space. We used solid carrier particles to prevent wash-out of biomass from the reactor at high hydraulic loading, and an up-flow system in order to be able to use very small carrier particles, maximizing the surface area for biomass attachment. In this paper we describe and discuss the results obtained with this type of anaerobic reactor (fluidised bed) at bench and semitechnical scale for wastewaters from pressurized ground wood pulping and paper manufacture, sulphite pulp evaporator condensate and bleach waste. Earlier work with Kraft pulp bleaching effluent and thermomechanical pulping wastewater and evaporator condensates using anaerobic reactors is also discussed. The results obtained thus far show that there are several wastewater streams from the pulping industry, where 60 to 90% of the dissolved organic pollutants (measured as COD_Cr or TOC) was biodegraded within 4 to 24 h. The high strength waste streams (COD_Cr 2000 mg O₂ 1⁻¹) allowed organic space load of 4 to 10 kg COD_Cr m⁻³ reactor volume d⁻¹. With low strength wastes the hydraulic loading was the limiting factor.     

A convenient electrochemical preparation of reduced methyl viologen and a kinetic study of the reaction with oxygen using an anaerobic stopped-flow apparatus

1. Single reduced methyl viologen (MV^.+) acts as an electron donor in a number of enzyme systems. The large changes in extinction coefficient upon oxidation (λ_max 600 nm; MV^.+, = 1.3 · 10⁴ M⁻¹ · cm⁻¹; oxidised form of methyl viologen (MV²⁺), = 0.0) make it ideally suited to kinetic studies of electron transfer reactions using stopped-flow and standard spectrophotometric techniques.

2. A convenient electrochemical preparation of large amounts of MV^.+ has been developed.

3. A commercial stopped-flow apparatus was modified in order to obtain a high degree of anaerobicity.

4. The reaction of MV^.+ with O₂ produced H₂O₂ (k > 5 · 10⁶ M⁻¹ · s⁻¹, pH 7.5, 25 °C). H₂O₂ subsequently reacted with excess MV^.+ (k = 2.3 · 10³ M⁻¹ · s⁻¹, pH 7.5, 25 °C) to produce water. The kinetics of this reaction were complex and have only been interpreted over a limited range of concentrations.

5. The results support the theory that the herbicidal action of methyl viologen (Paraquat, Gramoxone) is due to H₂O₂ (or radicals derived from H₂O₂) induced damage of plant cell membrane.     

Use of the glucose oxidase system for estimation of oxygen transfer rate in a solid-state bioreactor

The glucose oxidase system was adapted for estimation of the overall oxygen transfer rate in a periodic pressure oscillating, solid-state bioreactor. Enzyme concentration of 40 ml enzyme preparation L⁻¹ was found adequate to give linear gluconic acid production and attain maximal oxygen absorption rates. At 4 atm and 30°C, the oxygen transfer rate reached 892 mmol kg⁻¹ initial dry matter h⁻¹ in this system, while only 121 mmol kg⁻¹ initial dry matter h⁻¹ was obtained in a conventional static tray bioreactor.     

The non-specific inhibition of enzymes by environmental pollutants: a study of a model system towards the development of electrochemical biosensor arrays

Previous research has shown that lactate dehydrogenase (LDH) was competitively inhibited by pentachlorophenol (PCP) and a modified assay produced a detection limit of 1 μM (270 μg l⁻¹). This work used spectrophotometric rate-determination but in order to move towards biosensor development the selected detection method was electrochemical. The linkage of LDH to lactate oxidase (LOD) provided the electroactive species, hydrogen peroxide. This could be monitored using a screen-printed carbon electrode (SPCE) incorporating the mediator, cobalt phthalocyanine, at a potential of +300 mV (vs. Ag/AgCl). A linked LDH/LOD system was optimised with respect to inhibition by PCP. It was found that the SPCE support material, PVC, acted to reduce inhibition, possibly by combining with PCP. A cellulose acetate membrane removed this effect. Inhibition of the system was greatest at enzyme activities of 5 U ml⁻¹ LDH and 0.8 U ml⁻¹ LOD in reactions containing 246 μM pyruvate and 7.5 μM NADPH. PCP detection limits were an EC₁₀ of 800 nM (213 μg l⁻¹) and a minimum inhibition detectable (MID) limit of 650 nM (173 μg l⁻¹). The inclusion of a third enzyme, glucose dehydrogenase (GDH), provided cofactor recycling to enable low concentrations of NADPH to be incorporated within the assay. NADPH was reduced from 7.5 to 2 μM. PCP detection limits were obtained for an assay containing 5 U ml⁻¹ LDH, 0.8 U ml⁻¹ LOD and 0.1 U ml⁻¹ GDH with 246 μM pyruvate, 400 mM glucose and 2 μM NADPH. The EC₁₀ limit was 150 nM (39.9 μg l⁻¹) and the MID was 100 nM (26.6 μg l⁻¹). The design of the inhibition assays discussed has significance as a model for other enzymes and moves forward the possibility of an electrochemical biosensor array for pollution monitoring.     

Nutrient removal by thermophilic Fischerella (Mastigocladus laminosus) in a simulated algaculture process

A novel nutrient removal/waste heat utilization process was simulated using semicontinuous cultures of the thermophilic cyanobacterium Fischerella. Dissolved inorganic carbon (DIC)-enriched cultures, maintained with 10 mg l⁻¹ daily productivity, diurnally varying temperature (from 55°C to 26–28°C), a 12:12 light cycle (200 μE sec⁻¹ m⁻²) and 50% biomass recycling into heated effluent at the beginning of each light period, removed > 95% of NO₃⁻ + NO₂⁻−N, 71% of NH₃-N, 82% of PO₄³⁻ −P, and 70% of total P from effluent water samples containing approximately 400 μg l⁻¹ combined N and 60 μg l⁻¹ P. Nutrient removal was not severely impaired by an altered temperature gradient, doubled light intensity, or DIC limitation. Recycling 75% of the biomass at the end of each light period resulted in unimpaired NO₃⁻ + NO₂⁻ removal, 38–45% P removal and no net NH₃ removal. Diurnally varying P removal, averaging 50–60%, and nearly constant > 80% N removal, are therefore projected for a full-scale process with continuous biomass recycling.     

Anaerobic digestion of solid slaughterhouse waste (SHW) at laboratory scale: Influence of co-digestion with the organic fraction of municipal solid waste (OFMSW)

Mesophilic anaerobic digestion of slaughterhouse waste (SHW) and its co-digestion with the organic fraction of municipal solid waste (OFMSW) have been evaluated. These processes were carried out in a laboratory plant semi-continuously operated and two set-ups were run. The first set-up, with a hydraulic retention time (HRT) of 25 days and organic loading rate (OLR) of 1.70 kg VS m⁻³ day⁻¹ for digestion, and 3.70 kg VS m⁻³ day⁻¹ for co-digestion, was not successful. The second set-up was initiated with an HRT of 50 days and an OLR of 0.9 kg VS m⁻³ day⁻¹ for digestion and 1.85 kg VS m⁻³ day⁻¹ for co-digestion. Under these conditions, once the sludge had been acclimated to a medium with a high fat and ammonia content, it was possible to decrease the HRT while progressively increasing the OLR to the values used in the first set-up until an HRT of 25 days and OLRs of 1.70 and 3.70 kg VS m⁻³ day⁻¹, for digestion and co-digestion, respectively (the same conditions of the digesters failures previously). These digesters showed a highly stable performance, volatile fatty acids (VFAs) were not detected and long chain fatty acids (LCFAs) were undetected or only trace levels were measured in the analyzed effluent. Fat removal reached values of up to 83%. Anaerobic digestion was thus found to be a suitable technology for efficiently treating lipid and protein waste.     

Growth and biochemical characterization of microalgal biomass produced in bubble column and airlift photobioreactors: studies in fed-batch culture

Relatively large (0.19 m column diameter, 2 m tall, 0.06 m³ working volume) outdoor bubble column and airlift bioreactors (a split-cylinder and a draft-tube airlift device) were compared for monoseptic fed-batch culture of the microalga Phaeodactylum tricornutum. The three photobioreactors produced similar biomass versus time profiles and final biomass concentration (4 kg m⁻³). The maximum specific growth rate observed within a daily illuminated period in the exponential growth phase, had a value of 0.08 h⁻¹ on the third day of culture. Because of night-time losses of biomass, the specific growth rate averaged over the 4-days of exponential phase was 0.021 h⁻¹ for the three reactors.

The biomass in the vertical column reactors did not experience photoinhibition under conditions (photosynthetically active daily averaged irradiance value of 1150±52 μE m⁻² s⁻¹) that are known to cause photoinhibition in conventional thin-tube horizontal loop reactors. Because of good gas-liquid mass transfer, the dissolved oxygen concentration in the reactors at peak photosynthesis remained <120% of air saturation; thus, oxygen inhibition of photosynthesis and photo-oxidation of the biomass did not occur. Carbohydrate accumulation (up to 13% w/w) by the biomass was favored during light-limited linear growth. A declining light intensity caused a more than five-fold increase in cellular carotenoids but the chlorophylls increased only by about 2.5-fold during the course of the culture. In the stationary phase, up to 2% of the biomass was chlorophylls and carotenoids constituted up to 0.5% of the biomass dry weight.     

Effect of volumetric water content on thermal properties of dairy cattle feces mixed with sawdust

This paper describes the thermal properties (effective thermal conductivity and thermal diffusivity) of an organic waste used to model the composting process in relation to volumetric water content at 20°C. The organic waste was a mixture of fresh dairy cattle feces and sawdust with a ratio of one-to-one on a dry weight basis. The thermal probe method was used to determine the effective thermal conductivity and diffusivity. The effective thermal conductivities were found to increase with volumetric water content, and ranged from 0.0500 to 0.202 W m⁻¹ K⁻¹ at volumetric water contents of 0% and 44.2%, respectively. The thermal diffusivity was not affected by the volumetric water content, and was found to have a mean value of 1.08 × 10⁻⁷ m² s⁻¹.     

Use of genetically modified mice to examine the skeletal anabolic activity of vitamin D

We employed genetically modified mice to examine the role of 1,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃] on skeletal and calcium homeostasis. In mice expressing the null mutation for 25-hydroxyvitamin D 1 hydroxylase (1OHase^−/−), or the vitamin D receptor (VDR^−/−), 1,25(OH)₂D₃ and calcium were both required for optimal epiphyseal growth plate development, serum calcium and phosphorus alone were sufficient to mineralize skeletal tissue independent of 1,25(OH)₂D₃ and the VDR, and endogenous 1,25(OH)₂D₃ and the VDR were essential for baseline bone formation. In 2-week-old 1OHase^−/− mice and in 2-week-old mice homozygous for the PTH null mutation(PTH^−/−), PTH and 1,25(OH)₂D₃ were each found to exert independent and complementary effects on skeletal anabolism, with PTH predominantly affecting appositional trabecular bone growth and 1,25(OH)₂D₃ influencing both endochondral bone formation and appositional bone growth. Endogenous 1,25(OH)₂D₃ maintained serum calcium homeostasis predominantly by modifying intestinal and renal calcium transporters but not by producing net bone resorption. Administration of exogenous 1,25(OH)₂D₃ to double mutant PTH^−/−1OHase^−/− mice produced skeletal effects consistent with the actions of endogenous 1,25(OH)₂D₃. These studies reveal an important skeletal anabolic role for both endogenous and exogenous 1,25(OH)₂D₃ and point to a potential role for 1,25(OH)₂D₃ analogs in the treatment of disorders of bone loss.     

Biogas-plant effluent as an organic fertiliser in fish polyculture

Biogas-plant effluent collected from a KVIC model biogas-plant fed on cattle waste was utilised in fish polyculture. Biogas-plant effluent was applied at 0·15% concentration at 3-day intervals. The growth rate of Labeo rohita was 4·52 ±0 ·75 g fish⁻¹ day⁻¹, of Cirrhina mrigala 3·36 ± 0·48 g fish⁻ day⁻¹ and of Cyprinus carpio was 1·82 ± 0·41 g fish⁻¹ day⁻¹. Total fish production was 13·44 ± 0·77 kg 0·002 ha⁻¹ year⁻¹ (6653 kg ha⁻¹ year⁻¹) without any supplementary fish-feed.     

Vermiconversion of paper waste by earthworm born and grown in the waste-fed reactors compared to the pioneers raised to adulthood on cowdung feed

The performance of four species of earthworm--Eudrilus eugeniae, Kinberg, Drawida willsi Michaelsen, Lampito mauritii, Kinberg and Perionyx excavatus, Perrier--born and grown in vermireactors fed with paper waste was studied over six months, in terms of vermicast output per unit feed, production of offspring, and increase in worm zoomass. These were compared with the performance of the previous generation which had been raised to adulthood on cowdung as principal feed before shifting them to vermireactors operating on cowdung-spiked paper waste. The results indicated that except with D. willsi of which the second generation performed only a shade better than the first, there was significant improvement in vermicast output, animal growth, and reproduction in the second generation compared to the first. The results indicated that cowdung-spiked paper waste can be an adequate food for successive generations of earthworms and that reactors can be operated indefinitely on this feed. The results also indicated that the earthworm generations born and raised in vermireactors operated on this feed become better vermiconverters of this feed than the parent earthworms.     

Comparison of some novel polyculture and traditional monoculture vermicomposting reactors to decompose organic wastes

Efforts were made to evaluate the decomposition potentials of traditional monoculture and some novel polyculture vermireactors. Three earthworm species, i.e. Eisenia fetida (E. f.), Perionyx excavatus (P. ex.) and Lampito mauritii (L. m.), representing two different ecological categories: epigeic (E. fetida and P. excavatus) and anecic (L. mauritii), were used to design seven different vermireactors, i.e. Mono-(E. f.), Mono-(P. ex.), Mono-(L. m.), Poly-(E. f. + P. ex.), Poly-(P. ex. + L. m.), Poly-(E. f. + L. m.) and Poly-(E. f. + P. ex. + L. m.). The microbial load of vermireactors was evaluated through measuring dehydrogenises activities (DH-ase) and microbial biomass-N, while mineralization rate was measured in respect to changed level of some important nutrients in vermicomposted substrate. The vermicomposting caused decrease in pH (67.0–15.0%), organic C (46.1–28.4%) and C:N ratio (72.2–57.1%) and increase in total N (137.7–67.8%) as well as available P (107.9–16.9%) contents, at the end. The carbon and nitrogen mineralization rate showed the order: Poly-(E. f. + P. ex. + L. m.) > Poly-(E. f. + L. m.) > Poly-(P. ex. + L. m.) > Poly-(E. f. + P. ex.) > Mono-(E. f.) > Mono-(P. ex.) > Mono-(L. m.) for this study. The Poly-(E. f. + P. ex. + L. m.) vermireactor showed the maximum level of DH-ase activity 1926 ± 245 μg g⁻¹ substrate 24 h as well as microbial biomass-N 3059.1 ± 242.3 mg N g⁻¹ substrate, during experimentation. This study clearly suggests that burrowing earthworms in vermireactor not only promote the microbial colonization, but at the same time also accelerate the mineralization rate in decomposing waste. The polyculture vermicomposting, using burrowing earthworms with epigeics, could be more efficient than traditional monoculture vermireactors to decompose organic waste resources.