Effect of organic loading rate on the stability, operational parameters and performance of a secondary upflow anaerobic sludge bed reactor treating piggery waste

A study of anaerobic digestion of piggery wastewater was carried out in a laboratory-scale sludge bed reactor as a secondary treatment. The effect of organic volumetric loading rates (BV) in the range of 1.0-8.1 g TCOD/ld on the process performance was evaluated. The best results were obtained at BV equal to or lower than 4 g TCOD/ld. At higher BV values, the removal efficiency of the process decreased suddenly. A linear relationship was found between the effluent SCOD and the TVFA/alkalinity ratio (P). A relationship was found among the different operational variables (BV , removal efficiency, effluent soluble COD, soluble COD removal rate (R), retention factor (phi), specific microbial growth rate (mu), methane production rate per volume of reactor and per volume of waste treated--QM and qM, respectively) and the corresponding regression equations were obtained. An increase of BV determined a decrease of removal efficiency, phi and qM and an increase of effluent soluble COD, mu, R and QM. The value of the maximum specific microbial growth rate (muM) determined through the equation that correlated BV and mu was found to be 0.19 d(-1). This value was of the same magnitude as those reported in other works of anaerobic digestion of piggery waste.     

Lipid Production for Biofuels from Effluent-based Culture by Heterotrophic Chlorella Protothecoides

The effluent from a continuous-flow stirred tank reactor (CSTR) treating synthetic wastewater was used as an alternative carbon source to glucose for algal biomass and biodiesel production. The influence of the effluent on microalgal cell growth and lipid yield, as well as the utilization of volatile fatty acids (VFAs) in the effluent were investigated. The results indicate that C. protothecoides can proliferate in the CSTR effluent and accumulate biolipid. The final lipid content of the culture with the effluent feeding was 27?±?1.11 % after 168 h cultivation in flasks, which was higher than that with glucose of the same COD concentration. Valeric acid, ethanol, and butyric acid were favorable carbon sources for cell growth. The soluble microbial products (SMP) can be used as a carbon source for cell growth, and the existence of SMP could protect the cell from the inhibition caused by strong VFAs and improve the utilization of VFAs.     

Colour and AOX removal from pulping effluents by algae

A mixed culture of algae was used to treat pulping mill effluent in terms of removing both colour and adsorbably organic halides (AOX). The removal of AOX from pulping effluent increased with increasing initial colour value of the effluent. However, for the total mill effluent (composed of both pulping and bleaching effluents), AOX removal was found to be independent of initial colour value, and was around 70%. Up to 80% removal of colour from pulping effluent was achieved within 30 days under continuous lighting conditions. It was found that algae reduced the colour of pulping effluent of relatively low initial colour more efficiently than that of high initial colour. Under simulated field lighting conditions, up to 60% colour removal from pulping effluent was observed after 60 days of exposure, whereas for the total mill effluent it was up to 64% after 45 days. Total organic carbon and lignin (UVA₂₈₀) were also removed to a significant extent, suggesting that the mechanism of colour removal might not be transformation of the coloured lignin molecules to non-coloured ones. Analysis of alkaline extraction of the algal biomass and material balance findings indicated that the main colour removal mechanism was metabolism rather than adsorption. The experimental results were also analysed using multiple regression techniques and a mathematical model was developed to express the removal of colour from pulping effluents in terms of initial colour value, exposure time and lighting periods as well as interactions between these variables. Received: 12 January 1999 / Revision received: 25 March 1999 / Accepted: 26 March 1999     

用藻类监测和评价图们江的水污染

在图们江上、中游进行了人工基质着生藻类调查和室内栅藻检测,以监测和评价水污染状况。在所采用的野外监测指标中,以着生藻类总数与污染程度的关系最为明显。为便于比较和综合,采用了相对藻类总数(PN) 根据调查结果,提出了可作为图们江污染的指示种类。多样性指数与污染的关系,因受到其他非污染因子的影响,并不稳定。研究结果表明:图们江的主要污染源是尾矿废水(悬浮物)和纸浆废水(悬浮物、色度和有毒物质)。最严重污染江段为菜队到图们江段,次之为南坪江段。       

Photo-fermentation of Rhodobacter sphaeroides for hydrogen production using lignocellulose-derived organic acids

In this study, the corn stover was pretreated, enzymatically hydrolyzed, and then fermented in the lipid production fermentation. The corn stover fermentation effluent was utilized for the photo-fermentation of a Rhodobacter sphaeroides ZX-5 for hydrogen production. The hydrogen production was more than twofolds greater than that in the synthetic medium under the similar organic acid concentration range. The synergism among the pure organic acids was found to facilitate cell growth and hydrogen production, although some organic acid was not utilized for hydrogen production directly. The synergism among the components in the corn stover fermentation effluent was also found. The initial pH value was found to be an important parameter for the photo-fermentation of R. sphaeroide ZX-5 using the corn stover fermentation effluent. The results provided a possible way to utilize lignocellulose-derived organic acids for hydrogen production, and to treat fermentation wastewater in biofuel production using lignocellulose.     

Microalgal Biomass and Lipid Production on Dairy Effluent Using a Novel Microalga, <Emphasis Type="Italic">Chlorella</Emphasis> sp. Isolated from Dairy Wastewater

The present study focused on cost-effective production of microalgal biomass and lipid production on dairy effluent. The novel microalga, Chlorella sp. isolated from the dairy effluent showed high growth and lipid production on the undiluted and two-fold diluted dairy effluent which were four to five times higher than those of Chlorella vulgaris (control). The high growth of Chlorella sp. was thought to be possibly due to its heterotrophic growth capacity, high turbidity, COD, nutrients and trace elements. In contrast, C. vulgaris showed poor heterotrophic and photoautotrophic growth under the highly turbid conditions of dairy effluent. Both Chlorella sp. and C. vulgaris showed similar total FAME (mg FAME/g algal cells). The fatty acid composition analysis revealed that both Chlorella sp. and C. vulgaris possessed major C18 and C20 fatty acids which will be used for biodiesel production. Overall, the novel microalga, Chlorella sp. isolated from the dairy effluent showed high potential for cost-effective algal cultivation and lipid production on dairy effluent without any modification of process.     

Simultaneous nutrient removal and lipid production from pretreated piggery wastewater by Chlorella vulgaris YSW-04

The feasibility of using a microalga Chlorella vulgaris YSW-04 was investigated for removal of nutrients from piggery wastewater effluent. The consequent lipid production by the microalga was also identified and quantitatively determined. The wastewater effluent was diluted to different concentrations ranging from 20 to 80 % of the original using either synthetic media or distilled water. The dilution effect on both lipid production and nutrient removal was evaluated, and growth rate of C. vulgaris was also monitored. Dilution of the wastewater effluent improved microalgal growth, lipid productivity, and nutrient removal. The growth rate of C. vulgaris was increased with decreased concentration of piggery wastewater in the culture media regardless of the diluent type. Lipid production was relatively higher when using synthetic media than using distilled water for dilution of wastewater. The composition of fatty acids accumulated in microalgal biomass was dependent upon both dilution ratio and diluent type. The microalga grown on a 20 % concentration of wastewater effluent diluted with distilled water was more promising for generating high-efficient biodiesel compared to the other culture conditions. The highest removal of inorganic nutrients was also achieved at the same dilution condition. Our results revealed the optimal pretreatment condition for the biodegradation of piggery wastewater with microalgae for subsequent production of high-efficient biodiesel.     

Bioremediation potential of three carrageenophytes cultivated in tanks with seawater from fish farms

Intensive fish farming discharges large amount of nutrients, the majority of which are composed of dissolved nitrogen in ammonium form, which promotes eutrophication in coastal waters. Macroalgae have been proven to effectively reduce the nutrients of fish farm effluents and at the same time increase the economic output of the aquaculture system when economically important species are utilized. In this study, the potential of three high value carrageenophytes (Kappaphycus alvarezii, Kappaphycus sp., K. striatum) to extract ammonium in fish farm effluent collected from a milkfish (Chanos chanos) fish cage was investigated. To establish economic viability of the integrated culture system, the effects of elevated total ammonia of fish farm effluent on the growth rate, phycocolloid content, and quality of these seaweeds were determined. Tank cultivation trials showed that the three carrageenophytes substantially reduced the ammonium content of the fish farm effluent (41–66% reduction efficiency) and consequently attained maximum daily growth rates of 4.41%, 2.90%, and 2.75% for K. striatum, Kappaphycus sp., and K. alvarezii, respectively. Their carrageenan content was improved. Carrageenan quality, however, was not significantly enhanced. Elevated ammonium in fish farm effluent did not adversely affect the performance of tank cultivated Kappaphycus; thus, future integration of these seaweeds in fish farms is feasible. Presented at the 6th Meeting of the Asian Pacific Society of Applied Phycology, Manila, Philippines.     

Reuse of effluent water from a municipal wastewater treatment plant in microalgae cultivation for biofuel production

This study assessed the usability of effluent water discharged from a secondary municipal wastewater treatment plant for mass cultivation of microalgae for biofuel production. It was observed that bacteria and protozoa in the effluent water exerted a negative impact on the growth of Chlorella sp. 227. To reduce the effect, filtration or UV-radiation were applied on the effluent water as pre-treatment methods. Of all the pretreatment options tested, the filtration (by 0.2 μm) resulted in the highest biomass and lipid productivity. To be comparable with the growth in the autoclaved effluent water, the filtration with a proper pore size filter (less than 0.45 μm) or UV-B radiation of a proper dose (over 1620 mJ cm⁻²) are proposed. These findings led us to conclude that the utilization can be realized only when bacteria and other microorganisms are greatly reduced or eliminated from the effluent prior to its use.     

Usage of sewage effluent in irrigation of some woody tree seedlings. Part 3: Swietenia mahagoni (L.) Jacq.

A pot experiment was investigated to study the effect of sewage irrigation treatments (primary and secondary effluents) compared with tap water on the growth and chemical constituents of mahogany seedlings (Swietenia mahagoni (L.) Jacq.) as well as soil chemical properties. The experiment was conducted at a greenhouse in the nursery of Timber Trees Research Department of Sabahia, Horticultural Research Station in Alexandria, Egypt, from June 2003 to December 2004 for three irrigation periods (6, 12 and 18 months). The sewage effluent waters were taken from oxidation ponds located in New Borg EL-Arab city and used directly for irrigation.The primary effluent treatment was superior than other treatments in improving the growth parameters (plant height, stem diameter, leaf area, leaves number, fresh and dry weights of leaves, shoots and roots and shoot/root ratio) and showed the highest concentration and total uptake of N, P, K, Cd, Ni, Pb and Fe in plant parts, followed by secondary effluent then tap water. The data revealed that soil salinity in terms of electrical conductivity of saturated paste (EC), CaCO₃%, organic matter% and soluble anions and cations were influenced significantly by primary or secondary effluent treatment. The data also showed that the use of sewage effluent for irrigation increased N, P, K and DTPA-extractable-heavy metals (Cd, Cu, Ni, Pb, Fe, Mn and Zn). The effects of sewage effluent on growth parameters and elements content in plant parts and treated soil were more pronounced as water treatments were used for long period.The results suggested that the use of sewage effluent in irrigating mahogany trees grown on calcareous sandy loam soil was an important agriculture practice for improving soil properties, increasing fuel and timber production, and is an economic and safe way to dispose wastewaters.     

Bioremediation of sago industry effluent and its impact on seed germination (green gram and maize)

In this study, we attempted two investigational systems: one is treatment of sago industry effluent by aerobic bacterial consortium and the other is impact of treated and untreated effluent on seed germination. For the treatment system, the starch degrading bacteria were isolated from sago industry effluent and effluent contaminated soil. The genera, Alcaligenes, Bacillus and Corynebacterium were found efficient in starch degradation. The selected isolates were tested for their efficiency on the degradation of starch both in Mineral Salts Medium (MSM) and in sago industry effluent. About 85% of the starch was degraded in MSM by a bacterial consortium composed of Alcaligenes, Bacillus and Corynebacterium, whereas in effluent the degradation of starch was only 63%. The physico-chemical properties such as electrical conductivity, total solids, suspended solids, dissolved solids, BOD, COD, nitrogen and phosphate were found decreased in effluent after 72 h. The pH of the effluent was relatively increased from 3 to 6.7. The study of seed germination (maize and green gram) was carried out at 25, 50, 75 and 100% concentrations of treated and untreated effluent using soil sowing method. Shoot length, root length, fresh weight, dry weight and chlorophyll content showed an increase when treated effluent was tested whereas a decrease of growth was noticed in untreated effluent tested seedlings. The results revealed that effluent treated by aerobic microorganisms has no negative impact on the seed germination and can be effectively used for irrigation.     

The use of effluent from grass silage in the diet of finishing pigs. II. Assessment of nutritive value of fresh and stored effluent

Freshly collected effluent was treated with 2 ml formalin per litre and used to replace 150 g/kg of the dry matter of an all-meal control diet of bacon pigs. Diets containing effluent from either unwilted or wilted crops were compared with the control diet which was also given wet by adding water. Liveweight gains of 10 pigs per treatment from 65 to 86 kg on diets containing effluents from unwilted and wilted crops and on the control diet were 753, 715 and 719 ± 16.8 g/day, respectively, and in the same order feed conversion ratios (corrected to dry matter content of the control diet) were 2.94, 3.10 and 3.07 ± 0.075. None of these differences were significant. There were no significant differences in killing-out yield, in hardness of subcutaneous back-fat when measured by a penetrometer or in abnormal odour rating of subcutaneous back-fat.Formalin at levels of 1 and 2 ml/l and formic acid at levels of 1, 2 and 6 ml/l were added as potential preservatives to 1000 ml quantities of freshly collected silage effluent, which was then stored at 23°C. The 2 ml/l level of formalin and 6 ml/l level of formic acid prevented mould growth for 26 and 19 days, respectively.Freshly collected effluent was stored for 3.5, 14, 28, 56, 112 and 240 days after treatment, with formalin at the rate of 3 ml/l, and used in a pig-feeding trial. Pigs were fed either on a control all-meal diet or an equal dry matter intake of 150 g/kg effluent DM and 850 g/kg meal DM.A total of 120 animals were individually penned and fed twice daily on the experimental diets from 33 kg to slaughter at 82 kg liveweight. Overall mean liveweight gains for effluent and control diets were 646 and 656 ± 7.5 g/day, respectively, and the corresponding feed conversion ratios (DM basis) were 2.69 and 2.64 ± 0.030, neither of the differences being significant. Animal performance did not deteriorate with increasing period of effluent storage. No significant differences were found in carcase lean, back-fat thickness nor hardness of back-fat.A digestibility study was carried out on freshly collected effluent from another source. The level of dietary inclusion was equal to that in the previous experiments and the digestibility of dry matter was 0.831 and 0.819, and of nitrogen 0.822 and 0.827 for the control and effluent diets, respectively. A value of 11.4 MJ/kg dry matter was calculated by difference for the digestible energy of this effluent. In a further digestibility trial, digestible energy values of 14.6 and 14.2 MJ/kg dry matter were calculated by difference for effluents stored for 3.5 and 300 days, respectively.     

Converting corn wet-milling effluent into high-value fungal biomass in a biofilm reactor

Rhizopus microsporus was grown in an attached growth system using corn wet-milling effluent as a growth medium. This strain was chosen due to its ability to effectively degrade organic matter in corn wet-milling effluent and for its properties to produce significant levels of protein, chitin and chitosan. Fungal growth and organic removal efficiency were examined under both aseptic and non-aseptic conditions with and without nutrient supplementation. Plastic composite support (PCS) tubes, composed of 50% (w/w) polypropylene (PP) and 50% (w/w) agricultural products were used as support media. Significantly higher organic removal measured as chemical oxygen demand (COD) and biomass yield were observed in the bioreactor with PCS tubes than in two control bioreactors; that is with PP tubes alone and suspended growth (without support media). This confirmed that the PCS support medium with agricultural components enhanced fungal growth and organic removal. The results showed that supplementation of nutrients (e.g., mineral salts) under aseptic conditions enhanced the COD removal from 50% to 55% and observed biomass yield from 0.11 to 0.16 g (dry-weight)/g COD(removed) (i.e., from 0.10 to 0.14 g volatile solids (VS)/g COD(removed) approximately). Non-aseptic operation without nutrient supplementation resulted in an observed biomass yield of 0.32 g volatile suspended solids (VSS)/g COD(removed) with no significant improvement in COD removal ( approximately 53%); whereas with nutrient supplementation, the observed biomass yield increased to 0.56 g VSS/g COD(removed) and COD removal improved to 85%. The fungal system was able to degrade the organic matter with concomitant production of high-value fungal biomass. This is the first study that examined the conversion of corn milling waste stream into high value fungal protein.     

Influence of culture parameters on paper mill effluent decolourization by a white rot fungus Ganoderma lucidum

Efficacy of a white rot fungus G. lucidum for reduction of colour of paper mill effluent under various growth conditions was evaluated. G. lucidum cultured in IBME medium supported maximum colour reduction on 18th day of fungal growth. The optimization of growth parameters further improved colour reduction. The 18 day old culture at 4 g/l inoculum concentration resulted in maximum decolourization (89%) of the effluent with pH adjusted to 6.5 at 35 degrees C along with maximum reduction in biological oxygen demand and chemical oxygen demand. Relative contribution of lignin peroxidase and laccase to the decolourization of paper mill effluent by G. lucidum was also observed.     

Growth and mineral accumulation in Eucalyptus camaldulensis seedlings irrigated with mixed industrial effluents

Effects of mixed industrial effluents on growth, dry matter accumulation and mineral nutrient in Eucalyptus camaldulensis seedlings were studied. The objective was to evaluate the adaptability of E. camaldulensis to effluent, tolerance to excess/deficiency of mineral elements and ultimately to determine suitable combinations of industrial/municipal effluent for their use in biomass production in dry areas. Different irrigation treatments were: T(1): good water; T(2): municipal effluent; T(3): textile effluent; T(4): steel effluent; T(5): textile effluent+municipal effluent in 1:1 ratio; T(6): steel effluent+municipal effluent in 1:2 ratio; T(7): steel+textile+municipal effluent in 1:2:2 ratio; and T(8): steel+textile effluent in 1:2 ratio. High concentrations of metal ions and low concentrations of Ca, Mg, K, Na, N and P in soil and seedlings of T(4) resulted in mortality of the seedlings within a few days. Addition of the textile/municipal effluent increased the survival time of the seedlings for two to three months in T(6), T(7) and T(8) treatments. Among the remaining treatments, the seedlings of T(2) attained 131 cm height, 1.97 cm collar diameter, 19 total branches and produced 158 g seedling(-1) of dry biomass at the age of 10 months. The seedling of T(3) produced the least growth and biomass. Growth equivalent to that of the seedlings of T(1) treatment was achieved when municipal effluent was mixed with textile effluent (T(5)). There was a decrease in soil pH, EC, SOC, NH(4)-N, NO(3)-N, PO(4)-P and basic cations and increase in the concentration of Cu, Fe, Mn and Zn with T(4) treatment. The reverse trend was observed in T(3) where a high concentration of Na might have reduced Mg and micronutrient concentration in seedlings potentially affecting root and leaf growth. Mixing of effluents may be useful in tree irrigation to increase biomass productivity, which is evidenced by improved growth in T(5) and survival in T(6), T(7) and T(8) treatments. Further, reduction of toxic concentration of metal ions in effluents may be helpful for a long-term field application.     

Toxicity of high salinity tannery wastewater and effects on constructed wetland plants

The toxicity of high salinity tannery wastewater produced after an activated sludge secondary treatment on the germination and seedling growth of Trifolium pratense, a species used as indicator in toxicity tests, was evaluated. Growth was inhibited by wastewater concentrations >25% and undiluted effluent caused a complete germination inhibition. Constructed wetlands (CWs) with Arundo donax or Sarcocornia fruticosa were envisaged to further polish this wastewater. Selection of plant species to use in CWs for industrial wastewater treatment is an important issue, since for a successful establishment they have to tolerate the often harsh wastewater composition. For that, the effects of this wastewater on the growth of Arundo and Sarcocornia were assessed in pot assays. Plants were subject to different wastewater contents (0/50/100%), and both were resilient to the imposed conditions. Arundo had higher growth rates and biomass than Sarcocornia and may therefore be the preferred species for use in CWs treating tannery wastewater. CWs planted with the above mentioned plants significantly decreased the toxicity of the wastewater, as effluent from the CWs outlet stimulated the growth of Trifolium at concentrations <50%, and seed germination and growth even occurred in undiluted effluent.     

Genotoxicity assessment of a pharmaceutical effluent using four bioassays

Pharmaceutical industries are among the major contributors to industrial waste. Their effluents when wrongly handled and disposed of endanger both human and environmental health. In this study, we investigated the potential genotoxicity of a pharmaceutical effluent, by using the Allium cepa, mouse- sperm morphology, bone marrow chromosome aberration (CA) and micronucleus (MN) assays. Some of the physico-chemical properties of the effluent were also determined. The A. cepa and the animal assays were respectively carried out at concentrations of 0.5, 1, 2.5, 5 and 10%; and 1, 5, 10, 25 and 50% of the effluent. There was a statistically different (p < 0.05), concentration-dependent inhibition of onion root growth and mitotic index, and induction of chromosomal aberrations in the onion and mouse CA test. Assessment of sperm shape showed that the fraction of the sperm that was abnormal in shape was significantly (p < 0.05) greater than the negative control value. MN analysis showed a dose-dependent induction of micronucleated polychromatic erythrocytes across the treatment groups. These observations were provoked by the toxic and genotoxic constituents present in test samples. The tested pharmaceutical effluent is a potentially genotoxic agent and germ cell mutagen, and may induce adverse health effects in exposed individuals.     

The effects of a settled industrial domestic sewage works effluent from percolating filters on the embryo viability and hatching success of rainbow trout, Salmo gairdneri Richardson

The mortalities of washed and unwashed rainbow trout embryos exposed to Birmingham tap water, 50% and 100% settled effluent from filter beds has been compared. Differences in the hatching success between washed and unwashed embryos in the three treatments were also compared and the effect of saprophytic microbial growths assessed. There was a significant difference in mortality between washed embryos exposed to tap water (5%) and 50% effluent (12%) and 100% effluent (12%) when dissolved oxygen levels were maintained near 100% air saturation value. Mortalities of unwashed embryos were 4%, 26%, and 26% respectively for the three treatments. Hatching success of washed embryos was similar in the three treatments but unwashed embryos were significantly affected by the effluent treatments because of Sphaerotilus growths.     

Ettlia oleoabundans growth and oil production on agricultural anaerobic waste effluents

The feasibility of growth and oil production by Ettlia oleoabundans fed with anaerobic digester effluents of three agriculture wastes from the Arkansas Delta, catfish processing waste, soybean field waste, and rice hulls, was studied. Compared to standard BBM medium, all three effluents were deficient in phosphate and nitrate, but rich in ammonia and urea. Best growth was on 2% (v/v) soy effluent, but scant oil was produced on any of the effluents. When the three effluents were mixed, growth did not substantially increase, but oil content increased up to sixfold, depending on age of the effluent. Similar to growth in BBM, the main fatty acids produced were palmitic, oleic, and linoleic. These results show that anaerobically digested agricultural wastes can potentially support both growth and high oil productivity in E. oleoabundans.     

Effect of distillery effluent on seed germination in some vegetable crops

A laboratory experiment was conducted to study the effect of different concentrations (0%, 5%, 10%, 15%, 20%, 25%, 50%, 75% and 100%) of distillery effluent (raw spent wash) on seed germination (%), speed of germination, peak value and germination value in some vegetable crops: tomato, chilli, bottle gourd, cucumber and onion. The distillery effluent did not show any inhibitory effect on seed germination at low concentration except in tomato, but in onion the germination was significantly higher (84%) at 10% concentration as against 63% in the control. Irrespective of the crop species, at highest concentrations (75% and 100%), complete failure of germination was observed. The speed of germination, peak value and germination value also followed a similar trend. We found that a concentration of 5% was critical for seed germination in tomato and bottle gourd, and 25% in the rest of the crops. Based on the tolerance to distillery effluent, the crops studied have been arranged in the following order: cucumber > chilli > onion > bottle gourd > tomato. We conclude that the effect of the distillery effluent is crop-specific and due care should be taken before using the distillery effluent for pre-sowing irrigation purposes.