An Assessment of Variability of Pulp Mill Wastewater Treatment System Bacterial Communities using Molecular Methods

India’s current water use is around 600 BCM of which 60% is sourced from surface water bodies and 40% from ground. Consumption wise 89% is used by the agricultural sector, 7% by domestic, and 4% by industries. While agricultural sector water use can be considered to be a part of the water cycle, establishing techno-economic treatment systems and wastewater reuse facilities is essential for domestic and industrial sectors. Three stages of wastewater treatment systems are available—primary, secondary, and tertiary. Each stage provides varying qualities of treated water, with the tertiary systems providing the best water quality with total dissolved solids less than 50 parts per million (ppm) permitting its reuse in agriculture and industrial sectors. In India, only primary and secondary treatment systems are widely available. Tertiary systems are retrofitted now, to reuse water. Treated water reuse increases water security by preventing water pollution and decreasing stress on water bodies due to excessive water withdrawals. Preventing water pollution, treating water, and its reuse is vital; similarly, deployment of low-carbon sustainable technologies for water treatment is imperative. Else water pollution prevention efforts would reshape as air pollution issue. Energy consumption by a treatment system correlates to the air pollution potential. Primary, secondary, and tertiary treatment systems consume 2, 3, and 6 kWh/m3 electrical energy, respectively, in addition, the tertiary systems also require thermal energy which is about a kg steam for every 3 kg effluent to concentrate the waste (Tamil Nadu Water Investment Company Ltd. (TWIC), 2014). Environmental policies are therefore necessary to ensure the use of only sustainable treatment systems. Multiple effect evaporators are the widely used tertiary treatment system. It uses steam as a source of heating medium to evaporate wastewater. Steam used in MEE is of process heat quality with temperatures 150–200 °C and 10 bar pressure. The present chapter would discuss how conventional wastewater treatment systems could source their energy requirements sustainably and the policy implications surrounding such a promotion.

Energy and water autarky of wastewater treatment and power generation systems

SummaryTo quantify the major environmental drivers of stream bacterial population dynamics, we modelled temporal differences in stream bacterial communities to quantify community shifts, including those relating to cyclical seasonal variation and more sporadic bloom events. We applied Illumina MiSeq 16S rRNA bacterial gene sequencing of 892 stream biofilm samples, collected monthly for 36‐months from six streams. The streams were located a maximum of 118 km apart and drained three different catchment types (forest, urban and rural land uses). We identified repeatable seasonal patterns among bacterial taxa, allowing their separation into three ecological groupings, those following linear, bloom/trough and repeated, seasonal trends. Various physicochemical parameters (light, water and air temperature, pH, dissolved oxygen, nutrients) were linked to temporal community changes. Our models indicate that bloom events and seasonal episodes modify biofilm bacterial populations, suggesting that distinct microbial taxa thrive during these events including non‐cyanobacterial community members. These models could aid in determining how temporal environmental changes affect community assembly and guide the selection of appropriate statistical models to capture future community responses to environmental change.

The discriminatory powers of several techniques for typing Staphylococcus epidermidis were evaluated in an epidemiological study of bacteria isolated from intensive care patients and from neonates. Genomic DNA fingerprinting using BclI restriction endonuclease was an effective epidemiological marker. The distinct restriction fragment profiles produced with this enzyme were highlighted with specific probes in a Southern blot technique. Cloned Escherichia coli rRNA gene probes proved to have lower discriminatory power and be less suitable for intraspecies typing. However, a panel of random genomic Staphylococcus epidermidis DNA clones provided almost the same level of discrimination as the DNA fingerprinting technique and also provided a clearer profile. DNA and gene fingerprinting techniques were reproducible and highly discriminatory compared to typing based on antigen and plasmid profiles, antibiotic susceptibility patterns and biotypes.

DNA fingerprinting of benign and malignant breast lesions

A batch chlorination system was optimized for on-site wastewater treatment and reuse system (OWRS) and its efficiency was evaluated for reducing viruses, protozoa, bacteria and antimicrobial resistance in cold and warm seasons. The OWRS performance in reducing microbial contaminants was determined by assessing three different faecal indicators (Escherichia coli, F-specific coliphages and Clostridium perfringens for measuring the disinfection efficiency of bacteria, viruses and spore-formers and surrogate for protozoa, respectively) using culture-based methods. Quantitative PCR was used to quantify pathogenic bacteria (Shiga-toxin-producing E.coli (STEC), Campylobacter spp., and Arcobacter spp.), a human-associated faecal marker (gyrB), and tetracycline resistant bacteria (tetQ). The levels of E.coli, coliphages and Cl.perfringens showed 5·4, 2·3, 2·5 log reduction, respectively, upon disinfection. In the final effluents, coliphages (1·7×102 PFU 100ml-1 ) and Cl.perfringens (3·4CFU100ml-1 ) were detected in 80 and 100% of the samples, but E.coli was not found. The removal and inactivation of E.coli and Cl.perfringens were not significantly different across the seasons, however, efficacy of removal and inactivation of F-specific coliphage was significantly reduced during the winter/spring season compared to the summer/autumn season (P=0·009). The reduction of Arcobacter, gyrB and tetQ by 3·1, 2·3 and 2·3 log, respectively, was mostly due to peat biofiltration under the study conditions. This study demonstrated that peat biofiltration was the most important step of the OWRS to remove microbes and genes from wastewater before spray irrigation of the effluents. The irrigation system is not suitable for edible crops because of the potential presence of residual pathogens. On-site wastewater treatment systems are a practical option for reusing the wastewater for landscape, especially for those areas where geological and seasonal limitations impact the removal of microbial contaminants by soil infiltration.

The amphibian skin microbiome has been the focus of recent studies aiming to better understand the role of these microbial symbionts in host defense against disease. However, host-associated microbial communities are complex and dynamic, and changes in their composition and structure can influence their function. Understanding temporal variation of bacterial communities on amphibian skin is critical for establishing baselines from which to improve the development of mitigation techniques based on probiotic therapy and provides long-term host protection in a changing environment. Here, we investigated whether microbial communities on amphibian skin change over time at a single site. To examine this, we collected skin swabs from two pond-breeding species of treefrogs, Agalychnis callidryas and Dendropsophus ebraccatus, over 4 years at a single lowland tropical pond in Panamá. Relative abundance of operational taxonomic units (OTUs) based on 16S rRNA gene amplicon sequencing was used to determine bacterial community diversity on the skin of both treefrog species. We found significant variation in bacterial community structure across long and short-term time scales. Skin bacterial communities differed across years on both species and between seasons and sampling days only in D. ebraccatus. Importantly, bacterial community structures across days were as variable as year level comparisons. The differences in bacterial community were driven primarily by differences in relative abundance of key OTUs and explained by rainfall at the time of sampling. These findings suggest that skin-associated microbiomes are highly variable across time, and that for tropical lowland sites, rainfall is a good predictor of variability. However, more research is necessary to elucidate the significance of temporal variation in bacterial skin communities and their maintenance for amphibian conservation efforts.

Soil bacterial communities have significant influence on soilborne plant pathogens and, thus, crop health. The present study focuses on ribotyping soil bacterial communities in different peanut-cropping sequences in Alabama. The objective was to identify changes in microbial assemblages in response to cropping sequences that can play a role in managing soilborne plant pathogens in peanut. Four peanut-cropping sequences were sampled at the Wiregrass Research Station, Headland, AL in 2006 and 2007, including continuous peanut, 4 years of bahiagrass followed by peanut, peanut-cotton, and peanut-corn-cotton. Soil sampling was done at early and mid-season and at harvest. Bacterial community structure was assessed using ribosomal intergenic spacer analysis (RISA) combined with 16S rRNA cloning and sequencing. RISA results indicated >70% dissimilarities among different cropping sequences. However, 90% similarities were noticed among replicated plots of the same cropping sequences. Cropping sequences and time of soil sampling had considerable effect on soil microbial community structure. Bahiagrass rotation with peanut was found to have the highest bacterial diversity, as indicated by a high Shannon Weaver Diversity index. Overall, higher bacterial diversity was observed with bahiagrass and corn rotations compared with continuous peanut. The bacterial divisions Proteobacteria, Acidobacteria, Firmicutes, Bacteroidetes, and Actinomycetes were the predominant bacterial phyla found in all peanut-cropping sequences. The Proteobacteria taxa in these soils were negatively correlated with the abundance of members of division Firmicutes but, conversely, had a significant positive correlation with Gemmatimonadetes taxa. The prevalence of the division Actinomycetes was negatively correlated with the relative abundance of members of division Verrucomicrobia. These results indicate complex interactions among soil bacteria that are important contributors to crop health.

Campylobacter jejuni is one of the leading bacterial causes of food-borne illness in the USA. Molecular typing methods are often used in food safety for identifying sources of infection and pathways of transmission. Moreover, the identification of genetically related isolates (i.e., clades) may facilitate the development of intervention strategies for control and prevention of food-borne diseases. We analyzed the pan genome (i.e., core and variable genes) of 63 C. jejuni isolates recovered from chickens raised in conventional, organic, and free-range poultry flocks to gain insight into the genetic diversity of C. jejuni isolates recovered from different environments. We assessed the discriminatory power of three genotyping methods [i.e., pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and repetitive extragenic palindromic polymerase chain reaction (rep-PCR)]. The rep-PCR fingerprint was generated by determining the presence of repetitive sequences that are interspersed throughout the genome via repetitive extragenic palindromic PCR, enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR), and BOX element PCR (BOX-PCR) and combining the data to form a composite fingerprint. The genetic fingerprints were subjected to computer-assisted pattern analysis. Comparison of the three genotypic methods revealed that repREB-PCR showed greater discriminatory power than PFGE and MLST. ERIC-PCR and BOX-PCR yielded the highest number of PCR products and greatest reproducibility. Regardless of the genotyping method, C. jejuni isolates recovered from chickens reared in conventional, organic, and free-range environments all exhibit a high level of genotypic diversity.

To determine if there is a core microbial community in the microbial populations of different wastewater treatment plants (WWTPs) and to investigate the effects of wastewater characteristics, operational parameters, and geographic locations on microbial communities, activated sludge samples were collected from 14 wastewater treatment systems located in 4 cities in China. High-throughput pyrosequencing was used to examine the 16S rRNA genes of bacteria in the wastewater treatment systems. Our results showed that there were 60 genera of bacterial populations commonly shared by all 14 samples, including Ferruginibacter, Prosthecobacter, Zoogloea, Subdivision 3 genera incertae sedis, Gp4, Gp6, etc., indicating that there is a core microbial community in the microbial populations of WWTPs at different geographic locations. The canonical correspondence analysis (CCA) results showed that the bacterial community variance correlated most strongly with water temperature, conductivity, pH, and dissolved oxygen (DO) content. Variance partitioning analyses suggested that wastewater characteristics had the greatest contribution to the bacterial community variance, explaining 25.7% of the variance of bacterial communities independently, followed by operational parameters (23.9%) and geographic location (14.7%). Results of this study provided insights into the bacterial community structure and diversity in geographically distributed WWTPs and discerned the relationships between bacterial community and environmental variables in WWTPs.

Changes in bacterial communities by post-emergent herbicides in an Andisol fertilized with urea as revealed by DGGE

Investigating temporal variation in soil bacterial communities advances our fundamental understanding of the causal processes driving biological variation, and how the composition of these important ecosystem members may change into the future. Despite this, temporal variation in soil bacteria remains understudied, and the effects of spatial heterogeneity in bacterial communities on the detection of temporal changes is largely unknown. Using 16S rRNA gene amplicon sequencing, we evaluated temporal patterns in soil bacterial communities from indigenous forest and human-impacted sites sampled repeatedly over a 5-year period. Temporal variation appeared to be greater when fewer spatial samples per site were analysed, as well as in human-impacted compared to indigenous sites (P <0.01 for both). The biggest portion of variation in bacterial community richness and composition was explained by soil physicochemical variables (13-24%) rather than spatial distance or sampling time (<1%). These results highlight the importance of adequate spatiotemporal replication when sampling soil communities for environmental monitoring, and the importance of conducting temporal research across a wide variety of land uses. This will ensure we have a true understanding of how bacterial communities change over space and time; the work presented here provides important considerations for how such research should be designed.

Upflow Anaerobic Sludge Bed (UASB) wastewater (pre-)treatment systems represent a proven sustainable technology for a wide range of very different industrial effluents, including those containing toxic/inhibitory compounds. The process is also feasible for treatment of domestic wastewater with temperatures as low as 14-16 degrees C and likely even lower. Compared to conventional aerobic treatment systems the anaerobic treatment process merely offers advantages. This especially is true for the rate of start-up. The available insight in anaerobic sludge immobilization (i.e. granulation) and growth of granular anaerobic sludge in many respects suffices for practice. In anaerobic treatment the immobilization of balanced microbial communities is essential, because the concentration of intermediates then can be kept sufficiently low. So far ignored factors like the death and decay rate of organisms are of eminent importance for the quality of immobilized anaerobic sludge. Taking these factors into account, it can be shown that there does not exist any need for 'phase separation' when treating non- or slightly acidified wastewaters. Phase separation even is detrimental in case the acidogenic organisms are not removed from the effluent of the acidogenic reactor, because they deteriorate the settleability of granular sludge and also negatively affect the formation and growth of granular sludge. The growing insight in the role of factors like nutrients and trace elements, the effect of metabolic intermediates and end products opens excellent prospects for process control, e.g. for the anaerobic treatment of wastewaters containing mainly methanol. Anaerobic wastewater treatment can also profitably be applied in the thermophilic and psychrophilic temperature range. Moreover, thermophilic anaerobic sludge can be used under mesophilic conditions. The Expanded Granular Sludge Bed (EGSB) system particularly offers big practical potentials, e.g. for very low strength wastewaters (COD << 1 g/l) and at temperatures as low as 10 degrees C. In EGSB-systems virtually all the retained sludge is employed, while compared to UASB-systems also a substantially bigger fraction of the immobilized organisms (inside the granules) participates in the process, because an extraordinary high substrate affinity prevails in these systems. It looks necessary to reconsider theories for mass transfer in immobilized anaerobic biomass. Instead of phasing the digestion process, staging of the anaerobic reactors should be applied. In this way mixing up of the sludge can be significantly reduced and a plug flow is promoted. A staged process will provide a higher treatment efficiency and a higher process stability. This especially applies for thermophilic systems.

Aging wastewater collection and treatment systems have not received as much attention as other forms of infrastructure, even though they are vital to public health, economic growth, and environmental quality. Inflow and infiltration (I&I) are among potentially widespread problems facing central sewage collection and treatment systems, posing risks of sanitary system overflows (SSOs), system degradation, and water quality impairment, but remain poorly quantified. Whole-system analyses of I&I were conducted by regression analyses of system flow responses to rainfall and temperature for 93 wastewater treatment plants in 23 counties in eastern North Carolina, USA, a coastal plain region with high water tables and generally higher rainfalls than the continental interior. Statistically significant flow responses to rainfall were found in 92% of these systems, with 2-year average I&I values exceeding 10% of rainless system flow in over 40% of them. The effects of rainfall, which can be intense in this coastal region, have region-wide implications for sewer system performance and environmental management. The positive association between rainfall and excessive I&I parallels the effects of storm water runoff on water quality, in that excessive I&I can also drive SSOs, thus confounding water quality protection efforts.

How do grassland management history and bacterial micro-localisation affect the response of bacterial community structure to changes in aboveground grazing regime?