In this paper, a poultry slaughterhouse wastewater (PSW) was treated in terms of chemical oxygen demand (COD) and color reduction using electro-Fenton (EF) technique under response surface methodology (RSM). The effects of five significant independent variables such as reaction time, pH, H2O2/Fe2+ molar ratio, current density, volume ratio of H2O2/PSW (ml/l) were investigated on the COD and color removal. Experimental data were optimized by Box-Behnken design (BBD) and RSM. The optimum conditions were experimentally found at pH of 4.38, reaction time of 55.60 min, H2O2/Fe2+ molar ratio of 3.73, current density of 74.07 mA/cm2, volume ratio of H2O2/PSW of 1.63 ml/l for 92.37%COD removal and at pH of 3.39, reaction time of 49.22 min, H2O2/Fe2+ molar ratio of 3.62, current density of 67.90 mA/cm2, volume ratio of H2O2/PSW of 1.44 ml/l for 88.06% color removal.

A technique is proposed to treat saline hazardous wastewater by using marine activated sludge, cultivated with sea mud as seed. Since the developed marine activated sludge had phenol-tolerant microorganisms (MAS-1, MAS-2 and MAS-3) which originated from the ocean, it was envisaged that these bacteria could survive and breakdown phenol in saline environments. In this work, typical phenol-tolerant microorganisms were isolated from the marine activated sludge and identified. After a hierarchical acclimation process, the marine activated sludge was used to treat the industrial phenolic wastewater with high salinity. The marine activated sludge was able to break down phenol and other organic components effectively and efficiently in treating the wastewater with salinity of 5.7% w/v. The results showed a high removal of phenol (99%), COD (80%) and NH3-N (68%).

Worldwide, crude palm oil industries generate an overwhelming amount of palm oil mill effluent (POME). Since the past few decades, environmental issues associated with POME disposal have challenged the palm oil-producing nations which led them to reevaluate and develop their waste management strategies by using advanced biotreatment technologies. With the help of these technological advances, POME has emerged as a valuable biomass resource with great potential to produce sustainable renewable resources like biogas. This review entails various POME treatment methods in vogue and offers an insight into their improved applicability potential and pollution mitigation strategies by using proposed improved configurations like ponding system, open digesting tanks, anaerobic digestion based-bioreactors, aerobic anaerobic hybrid bioreactors, and membrane bioreactors. This review paper also gives an overview about the recent advancements in POME treatment bioreactor configurations and emphasizing their scope in large-scale applications on an industrial level. This review also critically analyzes their performance level to achieve the standard POME discharge limit by efficiently removing high COD (chemical oxygen demand), BOD (biological oxygen demand), and TSS (total suspended solid).

Ecological parameters based on multiply functional traits have many advantages for monitoring programs by reducing “signal to noise” ratios of observed species data. To identify potential indicators for bioassessment of marine pollution in function space, the functional patterns of protozoan communities and relationships with environmental changes were studied in coastal waters of the Yellow Sea during a 1-year period. The results showed that: (1) the spatial variability in functional trait distributions of the protozoa was significantly associated with changes in environmental variables, especially chemical oxygen demand (COD) and nutrients on spatial scale; (2) the functional traits, especially food resources and feeding type, were significantly correlated with COD and nutrients; and (3) the functional diversity indices were generally related to nutrients or COD. Based on the results, we suggest that the functional traits and diversity indices of protozoan communities may be used as more effective indicators for bioassessment of marine pollution.

The purpose of this study was to conduct a preliminary assessment of the potential impacts of Atlantic Canadian seafood processing effluents on the aquatic environment through physical-chemical characterization. Shellfish and finfish effluent samples were collected and characterized by biochemical oxygen demand (BOD5), chemical oxygen demand (COD), turbidity, total suspended solids (TSS), ammonia nitrogen (NH3-N), adsorbable organic halides (AOX), soluble BOD5 and soluble COD. Effluent concentration ranges were BOD5 (179 to 276mgL−1), COD (458 to 1717mgL−1), turbidity (28.8 to 88.3NTU), TSS (27.2 to 120.1mgL−1), NH3-N (1.5 to 12.9mgL−1) and AOX (3.2 and 0.4mgL−1) for flatfish and salmon processing effluents respectively, and cleanup shift AOX (3.5 and 0.5mgL−1). The characteristics of these effluents assessed have the potential to contaminate and degrade receiving water body environments. Improved performance may be possible with further treatment technology optimization on an effluent-specific basis.

According to our previous results on the magnesium-based exhaust gas cleaning system (Mg-EGCS), certain parameters of the desulphurization wastewater (such as chemical oxygen demand (COD), suspended solids (SS), total oil content and turbidity) were above the washwater discharge criteria set by the International Maritime Organization (IMO). In this work, a novel combined process of aeration-centrifugation and filter pressing was proposed, and a pilot-scale experiment was carried out to treat the desulphurization wastewater. The results demonstrated that the quality of wastewater treated by the combined process could meet the IMO’s washwater discharge standard, with COD of 115 mg/L, SS of <5 mg/L, polycyclic aromatic hydrocarbons (PAHs) of <1 μg/L, and total oil content of 5.1 mg/L, when the washwater flow rate was 0.45 m³/h.

The study investigated wastewater treatment in an aerobic reactor with activated sludge exposed to static magnetic field (SMF) with mean induction of 8.1 mT. The efficiency of chemical oxygen demand removal was about 90% in a control reactor and an SMF-exposed reactor. Although the nitrification efficiency was higher than 95% in both reactors, the activity of ammonia-oxidizing bacteria was higher in the SMF-exposed reactor. This resulted in shortening of nitrification time to 4 h compared to 8 h in the control reactor. Higher number of ammonia-oxidizing bacteria in the SMF-exposed reactor might result from increased oxygen penetration into the liquid exposed to SMF, which favored growth of these bacteria. The results indicate that SMF enhanced nitrification, the most sensitive process from the biological nitrogen transformations. SMF influenced the overall biomass content that was 14% higher in the SMF-exposed reactor than in the control reactor.

An aerobic denitrification system, initially bioaugmented with Pseudomonas strain T13, was established to treat coal-based ethylene glycol industry wastewater, which contained 3219 ± 86 mg/L total nitrogen (TN) and 1978 ± 14 mg/L NO₃ ⁻-N. In the current study, a stable denitrification efficiency of 53.7 ± 4.7% and nitrite removal efficiency of 40.1 ± 2.7% were achieved at different diluted influent concentrations. Toxicity evaluation showed that a lower toxicity of effluent was achieved when industry wastewater was treated by stuffing biofilm communities compared to suspended communities. Relatively high TN removal (~50%) and chemical oxygen demand removal percentages (>65%) were obtained when the influent concentration was controlled at below 50% of the raw industry wastewater. However, a further increased concentration led to a 20–30% decrease in nitrate and nitrite removal. Microbial network evaluation showed that a reduction in Pseudomonas abundance was induced during the succession of the microbial community. The napA gene analysis indicated that the decrease in nitrate and nitrite removal happened when abundance of Pseudomonas was reduced to less than 10% of the overall stuffing biofilm communities. Meanwhile, other denitrifying bacteria, such as Paracoccus, Brevundimonas, and Brucella, were subsequently enriched through symbiosis in the whole microbial network.

Microbial fuel cell (MFC) is a sustainable technology to treat cattle manure slurry (CMS) for converting chemical energy to bioelectricity. In this work, two types of allochthonous inoculum including activated sludge (AS) and domestic sewage (DS) were added into the MFC systems to enhance anode biofilm formation and electricity generation. Results indicated that MFCs (AS + CMS) obtained the maximum electricity output with voltage approaching 577 ± 7 mV (~ 196 h), followed by MFCs (DS + CMS) (520 ± 21 mV, ~ 236 h) and then MFCs with autochthonous inoculum (429 ± 62 mV, ~ 263.5 h). Though the raw cattle manure slurry (RCMS) could facilitate electricity production in MFCs, the addition of allochthonous inoculum (AS/DS) significantly reduced the startup time and enhanced the output voltage. Moreover, the maximum power (1.259 ± 0.015 W/m²) and the highest COD removal (84.72 ± 0.48%) were obtained in MFCs (AS + CMS). With regard to microbial community, Illumina HiSeq of the 16S rRNA gene was employed in this work and the exoelectrogens (Geobacter and Shewanella) were identified as the dominant members on all anode biofilms in MFCs. For anode microbial diversity, the MFCs (AS + CMS) outperformed MFCs (DS + CMS) and MFCs (RCMS), allowing the occurrence of the fermentative (e.g., Bacteroides) and nitrogen fixation bacteria (e.g., Azoarcus and Sterolibacterium) which enabled the efficient degradation of the slurry. This study provided a feasible strategy to analyze the anode biofilm formation by adding allochthonous inoculum and some implications for quick startup of MFC reactors for CMS treatment.

Singapore is an island city state with an economy dependent on petrochemicals and shipping, but with severely limited water resources. This study aimed to establish a suitable methodology specifically for the translation of a laboratory-scale system to an industrial scale for the treatment of phenol-contaminated wastewater. A habitat-specific microbial consortium was developed and reconstituted from 22 pure cultures dominated by Acinetobacter sp., Bacillus sp. and Pseudomonas sp. to form a synthetic biofilm-forming community with the capacity to degrade phenol-contaminated wastewater. The laboratory experiment was scaled-up to 400 m³ by using biotrickling reactors to reduce the phenol level from 407 mg L⁻¹ to below detection limit over 104 days incubation. The results showed that the microbial consortia could also reduce the toxicity of the wastewater while degrading the phenol and lowering the wastewater COD. Further, this approach could be translated into the field without the need for a purpose-built primary treatment facility preventing the generation of excessive biomass and eliminating the need for sludge disposal.