To obtain information that can be used as reference for improving the environment inside and surrounding the open channels receiving johkasou effluent, the formation and correlation of sediment bed bacterial density with water quality were evaluated with multivariate statistical analysis based on measured data for water and sediment samples collected for 8 times from 6 sites of an open channel that receives johkasou effluent in a residential area of Gifu Prefecture, Japan. Statistical analysis included principal component and factor analysis (PCA/FA), cluster analysis (CA) and correlation analysis. The PCA/FA results showed that 3 dominant factors were responsible for the water quality data structure, accounting for 85.12% of the total variance in the dataset. Hierarchical cluster analysis grouped 6 study sites into 3 statistically significant clusters, reflecting different characteristics and pollution levels of the sites. Correlation analysis revealed statistically significant relationships of the sediment bed bacterial density with BOD, total nitrogen and total phosphorus in the water of the channel receiving johkasou effluent.

Domestic wastewater generated from various types of buildings has been recognized to be different to some extent. This research aimed to know the quality, quantity, fluctuation of quality, and fluctuation of quantity of domestic wastewater discharged from office buildings. The composite samples were taken from two office buildings. The black water and gray water were taken from Building A with number of people 53 persons, and the mixed wastewater was taken both from Building A and Building B with number of people 900 persons. The fluctuation and quantity of wastewater were measured every hour from 7 am until 4 pm during the working time. The results showed that the quality of wastewater from office building contained 176 to 238 mg/L COD, 73.06 to 106.51 mg/L TN, and 3.66 to 7.70 mg/L TP with the average of C:N:P ratio was 100:42:2.56. Quantity of wastewater discharged from office buildings were from 39.61 to 49.93 liter/person/day. COD concentration changed significantly during the working time with mean ± standard (252.5±89). The quantity of wastewater varied over time and the peak discharge for black water and gray water were 2.85 litter/person/hour and 3.74 liter/person/hour, which occurred during the beginning of working time and the praying time of muslim Indonesian culture. It suggests that the domestic wastewater from office buildings has specific characteristics and it contains high concentration of nutrient that is required appropriate advanced technology for treating this kind of wastewater.

Aim: The modified Small-scale Domestic Sewage Treatment Plant (SDSTP) reactor with anaerobic fixed bed- aerobic Moving Bed Biofilm Reactor (MBBR) is implemented to find the optimum condition for organic degradation related to recirculation and intermittent aeration practices with the purpose to comply with the governmental regulation standard.  Methodology and Results: This research have been done with the artificial wastewater with characteristic similar to the sewage treatment plant (STP) of Telkom company with ratio C:N:P of characterized domestic wastewater is 252.40:85.42:3.01 that consists of glucose, NH4Cl, potassium dihydrogen phosphate, potassium nitrate, and sodium nitrite (NaNO2). Reactor design related with attached biomass in media until 2478.56 mg MLVSS.L-1 with the growth kinetics rate (μ) of 0.4691 day—1. The artificial wastewater is applied the determine the optimum variation of flow recirculation and periodic aeration in specific Hydraulics Retention Time (HRT) and Organic Loading Rate (OLR). In this research, the optimum recirculation ratio for organic degradation is 26.40 L.h-1 and the optimum aeration frequency variation is  12 hours in intermittent frequency with the maximum efficiency of organic degradation of 76.10% with the degradation efficiency real domestic wastewater application from STP Telkom company is 83.09%. Conclusion, significance and impact study:  Stover-Kincannon model is the best model with highest accuracy rate to model the degradation performance of organic compounds by the anaerobic fixed bed- aerobic MBBR SDSTP with determination coefficient 0.8623 and also degradation coefficient 38.121 day-1 compared with other models studied in this research.

Six biofilm carriers with different polymer were studied in fixed-film systems under anoxic conditions. Different media of polymers influence wastewater treatment performance. The aim of this study was to investigate different polymeric materials, polyethylene terephthalate (PET), polyvinyl chloride (PVC), polypropylene (PP), high-density polyethylene (HDPE), and polymethyl methacrylate (acrylic), that affect bacterial attachment and biofilm formation in biofilm-based wastewater treatment technologies. Water contact angle (WCA) measurement was employed to analyze the role of wetting (hydrophilic/hydrophobic) of polymeric material surfaces in the initial phase of bacterial attachment. The increase of biofilm formation during the observation was determined by gravimetric (total attached solid) and microscopic (SEM and CLSM) analysis. The results showed the value for WCA of PET < HDPE < PVC < PP < acrylic, which indicated that a higher hydrophilicity surface leads to a higher total attached solid (TAS), biofilm formation rate, and biofilm thickness on the surface of media. The hydrophilic material (i.e., PET and HDPE) demonstrated wastewater treatment performance better than slightly hydrophilic material (i.e., PVC, PP, and acrylic) under a steady-state period (over an 80-day operation). The data showed a positive correlation between hydrophilic material and COD, NH4+-N, and TP removal. Hydrophilic material was beneficial for a fast start-up and stable biofilm formation of a fixed-bed biofilm reactor. PET media showed feasible polymer types compared to HDPE, PVC, and PP; thus, it can be used as an alternative biofilm carrier media in a larger-scale application. The findings of this study highlighted the polymeric material type has a significant effect on the performance of fixed-bed wastewater treatment.

A johkasou system is getting popular as a decentralized wastewater treatment system in low-density communities. Treated waters of the johkasou systems, which are generally discharged into channels within residential areas before entering the local receiving water body, may contain microbial contaminants. To identify the characteristics of fecal indicators in the channels of the johkasou systems, the concentrations of fecal indicators (F-RNA bacteriophages, GIII F-RNA bacteriophages, Escherichia coli, and total coliforms) were examined both in water and sediment in the channels of three johkasou systems. These fecal indicators were always detected at high levels both in water and sediment in the channels of three johkasou systems through the study period. Significant differences in concentrations of fecal indicators were not observed among three johkasou systems in different residential areas. Concentrations of fecal indicators fluctuated in a day mainly due to domestic activities. Significant positive correlations of total coliforms and E. coli in water with total coliforms and E. coli in sediment suggest the potential importance of sediment on microbial dynamics in the channels of the johkasou systems. No significant correlations of F-RNA bacteriophages with total coliforms and E. coli indicate a specific distribution mechanism for F-RNA bacteriophages.