The impacts of cyanobacteria on pulp-and-paper wastewater toxicity and biodegradation of wastewater contaminants

This study investigated the effects of cyanobacteria from pulp-and-paper waste-treatment systems on biological toxicity removal and biodegradation of certain wastewater contaminants. In field and batch studies, using the Microtox assay, cyanobacterial biomass and final wastewater toxicity were significantly correlated. In softwood-based wastewater, a decrease in toxicity was negatively correlated with cyanobacterial biomass, but the correlation was positive in hardwood-based wastewater. In the softwood-based wastewater, toxicity remained higher in the light than it was in the dark, whereas in hardwood-based wastewater, toxicity was lower in the light than it was in the dark. All of these results were light-dependent, suggesting that the photosynthetic growth of cyanobacteria is required to induce significant effects. When grown in mixed cultures with bacterial degraders, cyanobacteria from pulp-and-paper waste-treatment systems generally impeded the biodegradation of the wastewater contaminants phenol and dichloroacetate (DCA). However, there was one case where the cyanobacterium Phormidium insigne improved the bacterial degradation of DCA. Doubling inorganic nutrient concentrations did not improve phenol or DCA biodegradation in the majority of cases, indicating that nutrient competition is not a major factor. These data suggest that cyanobacteria play an important role during the biological treatment of contaminants, and, hence, toxicity removal in pulp-and-paper waste-treatment systems.     

Optimization of spray drying process for Bacillus thuringiensis fermented wastewater and wastewater sludge

Response surface methodology was used to optimize spray drying process for producing biopesticide powders of Bacillus thuringiensis by using fermented broth of starch industry wastewater and wastewater sludge. Analysis of variance was carried out using number of viable spores in the powder as dependent variable. The determination coefficients of models were 92 and 94% for fermented broth of starch industry wastewater and wastewater sludge, respectively. Under the optimal conditions of the operational parameters of spray drying, the numbers of viable spores were 2.2 × 10⁸ and 1.3 × 10⁸ CFU/mg in the dry powders for starch industry wastewater and wastewater sludge respectively, with a loss of viable spores of 18 and 13% when compared with their respective fermented broths. The entomotoxicity (measured by the bioassay method) of the powders obtained under optimal conditions showed a loss of 28 and 18% when compared with the fermented broth of starch industry wastewater and wastewater sludge, respectively. The optimized results of spray drying were used for field application calculations. The volume of fermented broth required to produce powder formulated product when compared with the volume required for liquid formulation product in order to treat 1 ha of balsam fir was less and offered several advantages.     

Simultaneous treatment of municipal wastewater and biodiesel production by cultivation of Chlorella vulgaris with indigenous wastewater bacteria

This study examined the use of Chlorella vulgaris for the simultaneous bioremediation of municipal wastewater and production of biodiesel. We tested the effect of wastewater dilution on C. vulgaris growth in filtered and sterilized wastewater, sterilized wastewater, and untreated wastewater. Growth was the greatest in untreated wastewater, suggesting that certain wastewater components, such as bacteria, may promote microalgal growth. We confirmed the presence of beneficial bacteria by denaturing gradient gel electrophoresis analysis and inoculation of wastewater bacteria into microalgal cultures in artificial medium. Furthermore, we employed a semi-continuous cultivation process that successfully combined the advantages of indigenous bacteria with a high level of inoculum. Finally, cells grown in wastewater contained high levels of useful fatty acids. Collectively, our data suggest that it may be feasible to use wastewater-grown C. vulgaris biomass for simultaneous bioremediation and biodiesel production.     

Bacteriophage biocontrol in wastewater treatment

Waterborne bacterial pathogens in wastewater remains an important public health concern, not only because of the environmental damage, morbidity and mortality that they cause, but also due to the high cost of disinfecting wastewater by using physical and chemical methods in treatment plants. Bacteriophages are proposed as bacterial pathogen indicators and as an alternative biological method for wastewater treatment. Phage biocontrol in large scale treatment requires adaptive and aggressive phages that are able to overcome the environmental forces that interfere with phage–host interactions while targeting unwanted bacterial pathogens and preventing biofilms and foaming. This review will shed light on aspects of using bacteriophage programming technology in wastewater plants to rapidly target and reduce undesirable bacteria without harming the useful bacteria needed for biodegradation.     

Biodegradability of tannin-containing wastewater from leather industry

Tannins occur commonly in the wastewaters from forestry, plant medicine, paper and leather industries. The treatment of this kind of wastewaters, including settling and biodegradation, is usually difficult because tannins are highly soluble in water and would inhibit the growth of microorganisms in activated sludge. The objective of this study is to investigate biodegradability of tannin-containing wastewaters, so as to characterize the pollution properties of such wastewaters and provide a reference for their biological treatment in wastewater treatment plants. The research was typified by using the wastewater collected from vegetable tanning process in leather industry. A model was developed to describe the activated sludge process, and the biodegradation kinetics of vegetable tanning wastewater (VET wastewater) was studied. It was found that the biodegradability of tannin-containing wastewater varies heavily with the content of tannins in wastewater. The biodegradation of VET wastewater with tannin content around 4,900 mg/l occurred inefficiently due to the inhibition of tannins to the activated sludge process, and only 34.7% of biodegradation extent was reached in 14 days of incubation. The optimal biodegradability of VET wastewater was observed when its tannin content was diluted to 490 mg/l, where the COD and tannin removals reached 51.3% and 45.1% respectively in 6 days. Hence, it is suggested that a proper control of tannin content is necessary to achieve an effective biodegradation of tannin-containing wastewaters in wastewater treatment plants.     

可持续的污水处理过程与展望

传统上,污水在处理过程中其所含有的能源和营养物质等也被消耗了。可持续的水处理不仅包括污水无害化处理,还包括能源和营养物的综合回收利用。综合论述了可持续的污水处理概念、理论、方法和污水处理过程中物质回收技术的发展。     

Improvement in post-treatment of digested swine wastewater

The performance of sequencing batch reactor (SBR) during post-treatment of digested effluent of swine wastewater was investigated. While operating SBR to treat the digested effluent directly, the performance was very poor with COD removal rate about 10%, and NH4+-N removal rate nearly 50%, with a scarce removal of total phosphorus. The performance apparently improved after adding raw swine wastewater or alkali to digested effluent. Although similar results for NH4+-N removal were achieved adopting both measures, the addition of raw wastewater proved superior in removing total nitrogen and total phosphorus. The addition of raw wastewater obtained effluent COD around 300 mg/L which was lower than that after alkali addition i.e. around 550 mg/L. Judged from the investment, oxygen demand, sludge yield, biogas production and running cost, the traditional combined anaerobic-SBR process is unfeasible to treat swine wastewater, while the combined anaerobic-SBR process with addition of raw swine wastewater can be a suitable biotechnology.     

Nitrogen removal enhanced by shunt distributing wastewater in a subsurface wastewater infiltration system

Three pilot subsurface wastewater infiltration systems filled with the same mixed matrix made of 80% brown soil and cinder at a weight of 20% were constructed in the laboratory. All systems worked successfully in the intermittent feeding mode with total hydraulic loading of 4 m³/(m² d) for over 2 months, with the optimal parameters of shunt ratio of 1:1 and shunt position at the depth of 0.7 m was achieved on the basis of large amounts of experimental data. The experiment results showed that shunt distributing wastewater could significantly improve the nitrogen removal in the subsurface infiltration system and the average removal rates of TN and NH₄-N increased by 10% and 5.67%, respectively. Shunt distributing wastewater had little influence on the removal rates of COD and TP. The results suggested that shunt distributing wastewater was simple and effective for nitrogen removal.     

Bacterial communities in industrial wastewater bioreactors

Wastewater bioreactors have been used to treat domestic and industrial waste for nearly a century. Development of molecular tools such as PCR and DNA microarrays have enabled identification and characterization of some of the microbes in these bioreactors; however, molecular characterization of the microbes is still in its infancy, and only a few of the molecular tools have been applied to improving performance of wastewater bioreactors at the commercial level. Several new plasmids and enzymes have been isolated from wastewater bioreactors. There is enormous opportunity to use the microbes from wastewater for industrial bioprocesses.     

Ultrafiltration recovery of entomotoxicity from supernatant of Bacillus thuringiensis fermented wastewater and wastewater sludge

The study investigates the recovery of active components (crystal proteins, spores and other factors of virulence) of Bacillus thuringiensis (Bt) based biopesticides from centrifuged supernatant, by ultrafiltration. The centrifuged fermented broths comprised, starch industry wastewater, non-hydrolyzed and hydrolyzed wastewater sludge and semi-synthetic soya medium (as control). The ultrafiltration membrane of 5 kDa gave highest recovery of the active components and increased the entomotoxicity in the retentates by 7.9%, 10.5%, 9.0%, 5.7%, for semi-synthetic soya medium, starch industry wastewater, non-hydrolyzed and hydrolyzed wastewater sludge, respectively. However, the retention of suspended solids on the membrane (measured via mass balance) varied with the type of fermented broths and was very high for hydrolyzed sludge (soya-15%; starch industry wastewater-12%; non-hydrolyzed sludge-7% and hydrolyzed sludge-68%). This reflected the deposit on the membrane. In the given context, scale-up of the ultrafiltration process will give better efficacy for non-hydrolyzed sludge and starch industry wastewater in comparison to soya and hydrolyzed sludge medium.     

Recycling of aquaculture wastewater using charcoal based constructed wetlands

Abstract

The competitive demand for water makes it a scarce resource for agricultural use. This necessitates wastewater reuse for irrigation and any other agricultural purpose, especially in developing countries where treatment of wastewaters is not a priority. The aim of this study was to evaluate the performance of a charcoal-based constructed wetland (CBCW) in treating aquaculture wastewater. Aquaculture wastewater from a Research Fishpond Farm was treated in a CBCW planted with Sacciolepsis africana and Commelina cyannae for 5?days retention time. Raw wastewater and the treated wastewater from the constructed wetland (CW) was sampled and the physicochemical parameters determined. The performance of the CW in treating aquaculture wastewater was conducted. The result showed that the CBCW was capable of removing 50% TSS, 88% COD, 93% BOD_5, and 100% nitrate nitrogen. The pH and DO of the wastewater before treatment and after treatment ranged from 6.68 to 6.91 and 4.13 to 6.30?mg/l, respectively. Thus, CWs have great potential for the treatment of aquaculture wastewater and prevention of environmental degradation through wastewater treatment, thereby solving the problem of water scarcity for agriculture for optimum food production.     

Fungal remediation of Amarula distillery wastewater

Amarula Cream is an alcoholic beverage derived from the distillation of fermented marula fruit and to date there is no scientific data as to the characteristics of the distillery wastewater generated from its production. The wastewater was found to have a chemical oxygen demand (COD) of 27 g/l, a pH of 3.8, a high concentration of phenolic compounds (866 mg/l) and a high suspended solids content (10.5 g/l), all of which could adversely affect biological treatment. Full-strength wastewater was treated using shake-flask monocultures of four white rot fungi (Trametes pubescens MB 89, Ceriporiopsis subvermispora, Pycnoporus cinnabarinus or Phanerochaete chrysosporium) at pH 5.0 with no additional carbon or nitrogen supplements. Trametes pubescens performed the best with regards to degrading phenolic compounds, COD and colour, while P. cinnabarinus improved the pH to the greatest extent. Laccase synthesis was only detected in the T. pubescens and C. subvermispora cultures. Six wastewater concentrations (100, 80, 60, 40, 20 and 10%) were assessed at pH 4.5 to establish an optimum concentration for remediation and laccase production by T. pubescens. Similar COD removal efficiencies (71–77%) and phenolic removal efficiencies (87–92%) were achieved at all concentrations. The phenolic removal efficiencies improved by approximately 5% compared to the screening experiment at pH 5.0, indicating that the laccase was more efficient at pH 4.5. The pH became more basic as a result of treatment and the colour decreased for samples below 60% wastewater concentration. The maximum laccase activity (1063 ± 26 units/l) was obtained in the 80% wastewater concentration. This study has resulted in the first characterization of Amarula distillery wastewater and showed that it has a high phenolic compound concentration, COD and suspended solids content. It was possible to biologically treat the wastewater at full strength using a number of white-rot fungi just by raising the pH.     

Innovative graphene microbial platforms for domestic wastewater treatment

Supplying clean water to fulfill human requirements is one of this century’s priorities. Global water resources are barely aligned with the rising demand, which is further aggravated by rising population, climate change and water quality problems. Consequently, there is a persistent need for innovative technologies to valorize unconventional water resources such as domestic wastewater. Graphene holds promising prospects in developing domestic wastewater treatment to qualitatively enhance treatment efficiency and quantitatively increase water supply. This review highlights the existing wastewater treatment processes along with their challenges according to South Australian wastewater treatment plants (WWTPs) which are representative of many modern WWTPs. The discussion will also cover the current and potential applications of graphene for domestic wastewater treatment, as well as obstacles and research priorities required for commercialization.     

植物在水产养殖废水处理中的研究进展

植物在生长繁殖过程中能吸收利用、富集、吸附和固定水产养殖水体中的有机物、无机物和重金属,降低养殖水体中的TP、TN、TSS、COD和BOD。同时,植物在水体中可通过其发达的通气组织和根系传输氧气,为微生物和其他生物的代谢活动提供适宜的条件。选择合适的植物构建人工湿地,通过人工湿地中植物、微生物和基质的物理作用、化学作用和生物作用处理水产养殖废水,可建立循环的水产养殖模式。将植物应用于水产养殖废水的处理,是实现可持续发展的生态型水产养殖的基础。本文综述了近年来藻类和高等植物在水产养殖废水处理中的研究进展。     

Prevalence and fate of giardia cysts in wastewater treatment plants

The present study was conducted to review factors affecting the prevalence and concentration of Giardia in raw wastewater. The removal and inactivation efficiency of Giardia by wastewater treatment technologies was also reviewed. Data published for the prevalence of Giardia in wastewater and the removal by wastewater treatment plants was reviewed. Giardia cysts are highly prevalent in wastewater in various parts of the world, which may reflect the infection rate in the population. In 23 of 30 (76·6%) studies, all of the tested raw wastewater samples were positive for Giardia cysts at concentrations ranging from 0·23 to 100 000 cysts l^?1. The concentration of Giardia in raw wastewater was not affected by the geographical region or the socio‐economic status of the community. Discharge of raw wastewater or the application of raw wastewater for irrigation may result in Giardia transmission. Activated sludge treatment resulted in a one to two orders of magnitude reduction in Giardia, whereas a stabilization pond with a high retention time removed up to 100% of the cysts from wastewater. High‐rate sand filtration, ultrafiltration and UV disinfection were reported as the most efficient wastewater treatment methods for removal and disinfection of Giardia cysts. Wastewater treatment may not totally prevent the environmental transmission of Giardia cysts. The reviewed data show that a combination of wastewater treatment methods may results in efficient removal of Giardia cysts and prevent their environmental transmission.     

Microalgae wastewater treatment: Biological and technological approaches

Current global environmental issues raise unavoidable challenges for our use of natural resources. Supplying the human population with clean water is becoming a global problem. Numerous organic and inorganic impurities in municipal, industrial, and agricultural waters, ranging from microplastics to high nutrient loads and heavy metals, endanger our nutrition and health. The development of efficient wastewater treatment technologies and circular economic approaches is thus becoming increasingly important. The biomass production of microalgae using industrial wastewater offers the possibility of recycling industrial residues to create new sources of raw materials for energy and material use. This review discusses algae‐based wastewater treatment technologies with a special focus on industrial wastewater sources, the potential of non‐conventional extremophilic (thermophilic, acidophilic, and psychrophilic) microalgae, and industrial algae‐wastewater treatment concepts that have already been put into practice.     

Sequencing batch biofilter granular reactor for textile wastewater treatment

Textile wastewater is difficult to treat as it usually contains considerable amounts of different pollutants, which are often recalcitrant, toxic and inhibitory. Therefore, complex treatment schemes based on the sequence of various steps are usually required for an effective treatment. This explains why textile effluents are often treated in centralized plants and sometimes mixed with municipal wastewater. The adoption of new technologies for on-site treatment, instead, would be optimal, deeply reducing treatment costs. An innovative technology exhibiting several characteristics appropriate for the attainment of such a goal is sequencing batch biofilter granular reactor (SBBGR). To assess the suitability of this technology, two lab-scale reactors were operated, treating mixed municipal-textile wastewater and a pure textile effluent, respectively. Results have demonstrated that mixed wastewater can be successfully treated with very low hydraulic retention times (less than 10 hours). Furthermore, SBBGR shows to be an effective pre-treatment for textile wastewater for discharge into sewer systems. The economic evaluation of the process showed operative costs of 0.10 and 0.19 € per m(3) of mixed wastewater and textile wastewater, respectively.     

Microalgae and wastewater treatment

Organic and inorganic substances which were released into the environment as a result of domestic, agricultural and industrial water activities lead to organic and inorganic pollution. The normal primary and secondary treatment processes of these wastewaters have been introduced in a growing number of places, in order to eliminate the easily settled materials and to oxidize the organic material present in wastewater. The final result is a clear, apparently clean effluent which is discharged into natural water bodies. This secondary effluent is, however, loaded with inorganic nitrogen and phosphorus and causes eutrophication and more long-term problems because of refractory organics and heavy metals that are discharged. Microalgae culture offers an interesting step for wastewater treatments, because they provide a tertiary biotreatment coupled with the production of potentially valuable biomass, which can be used for several purposes. Microalgae cultures offer an elegant solution to tertiary and quandary treatments due to the ability of microalgae to use inorganic nitrogen and phosphorus for their growth. And also, for their capacity to remove heavy metals, as well as some toxic organic compounds, therefore, it does not lead to secondary pollution. In the current review we will highlight on the role of micro-algae in the treatment of wastewater.     

A novel membrane bioreactor for detoxifying industrial wastewater: II. Biodegradation of 3-chloronitrobenzene in an industrially produced wastewater

A novel membrane bioreactor has been used for the treatment of an industrially produced wastewater arising in the manufacture of 3-chloronitrobenzene. This wastewater is not amenable to direct biological treatment without some form pretreatment or dilution, due to the inorganic composition (pH <1, salt concentration 4% w/w) of the wastewater. In the membrane bioreactor, the organic pollutants are first separated from the wastewater by selective membrane permeation, and then biodegraded in the biological growth compartment of the bioreactor. At a wastewater flow rate of 64 mL h(-1) (corresponding to a contact time of approximately 1.7 hours) over 99% of the 3-chloronitrobenzene and over 99% of the nitrobenzene in the wastewater were degraded. Degradation of 3-chloronitrobenzene was accompanied by evolution of chloride ions in a stoichiometric ratio. Both 3-chloronitrobenzene and nitrobenzene degradation were accompanied by the evolution of carbon dioxide; approximately 80% of the carbon entering the system was oxidized to CO(2) carbon. Analysis of mass transport across the membrane revealed that 3-chloronitrobenzene and nitrobenzene are transported more rapidly than phenol. This is explained in terms of a resistances-in-series model, which shows phenol transfer to be rate limited by the membrane diffusion step, whereas the chloronitrobenzene and nitrobenzene transfer are rate limited by the liquid film mass transfer. (c) 1993 Wiley & Sons, Inc.     

Treatment of turkey processing wastewater with sand filtration

This research investigated the feasibility of coarse/fine sand filtration for removing organic materials from turkey processing wastewater. Sand filtration was tested with three organic and hydraulic loadings. Six two-layer sand bioreactors were in three groups, each with 5 cm layer of pea gravel at the bottom to support layers of fine sand (46 cm) and coarse sand (15 cm) to a height of 66 cm. The bioreactors were inoculated with a mixture of 20% (vol/vol) of wastewater lagoon sludge, 40% (vol/vol) of turkey processing wastewater, and 40% (vol/vol) of BOD(5) dilution water before starting the column operation with turkey processing wastewater. The wastewater contained 1270+/-730 mg COD/L and was applied to each sand bioreactor at hydraulic loading rates of 94% during 80 days of column operation at low and medium hydraulic loading rates (132 L/m(2)/day). The removal at the highest hydraulic loading rate (264 L/m(2)/day) declined after the appearance of a black zone in the top layer of fine sand on day 30 for one reactor and day 50 for the other. The sand filtration in this study represents a feasible treatment for turkey processing wastewater and its efficiency and the life span of the process are associated with the extent of hydraulic loading of the sand bioreactors.