Abstract Studies in water quality management have indicated significant relationships between land use/land cover (LULC) variables and water quality parameters. Thus, understanding this linkage is essential in protecting and developing water resources. This article extends the conventional geographical weighted regression (GWR) to a temporal version in order to take both spatial and temporal variations of such linkages into account, which has been ignored by many of the previous efforts. The approach has been evaluated for total nitrates and nitrites' concentration as the case study. For this, observations of 45 water quality sampling stations were examined in a time interval of 20 years (1992–2011), and the linkages between LULC variables and NO2 + NO3 concentration were extracted through Pearson correlation coefficient as a global regression model, the conventional geographic weighted regression, and the proposed spatio-temporal weighted regression (STWR). Comparing the results based on two global criteria of goodness-of-fitness (R2) and residual sum of squares (RSS) verifies that the simultaneous consideration of spatial and temporal variations by STWR substantially improves the results.

Abstract The present study aimed to: (i) identify helminth eggs and protozoan cysts in wastewater samples to which both human and animals could be exposed when they are reused in agriculture; and (ii) evaluate the efficiency of their removal by two wastewater treatment systems (activated sludge and lagoon). For these purposes, 234 wastewater samples (117 raw, 117 treated) were collected from 20 wastewater treatment plants (WWTPs) in Tunisia over a one-year sampling period. Parasitic load was enumerated by the modified Bailenger method. The results showed that helminth eggs found were Nematodes mainly represented by Ascaris sp. (95%), Hookworm species (50%), and Enterobius vermicularis (45%). For Cestodes, species identified were Taeniid eggs (85%), Hymenolepis nana (70%), Hymenolepis diminuta (55%) and digestive Strongyles. Among protozoa, Giardia sp., Entamoeba histolytica/dispar/moshkovskii and Entamoeba coli cysts were found in 100% of raw wastewater samples. The overall removal efficiency of helminth eggs and protozoan cysts in the treatment plants ranged from 56.5 to 100% and from 50.4 to 95.5%, respectively. The result from Multiple Correspondence Analysis (MCA) shows that the close clustering of the parasitic mean removal levels indicates that there is little difference in wastewater treatment processes between the WWTPs examined.

Abstract This paper aims to: (1) develop models based on adaptive neuro-fuzzy inference system (ANFIS) able to predict five-day biochemical oxygen demand (BOD5) in Ouizert reservoir; (2) demonstrate the capability of the ANFIS in the practical issues of water quality management; (3) choose the optimal combination of input variables to improve the model performance; (4) compare two ANFIS partition methods, namely subtractive clustering called ANFIS-SC and grid partitioning, called ANFIS-GP. The models were developed using experimental data which were gathered during a ten-year period, at a mean monthly time step (scale). The input data used are total inorganic nitrogen, chemical oxygen demand (COD), total dissolved solid, dissolved oxygen and phosphate; the output is five-day biochemical oxygen demand (BOD5). Results reveal that ANFIS-SC models gave a higher correlation coefficient, a lower root mean square errors (RMSE) and mean absolute errors than the corresponding ANFIS-GP models. We can conclude that ANFIS-SC has supremacy over ANFIS-GP in terms of performance criteria and prediction accuracy for BOD5 estimation. The results showed that COD is the more effective variable for BOD5 estimating than other parameters, hence COD is the major driving factor for BOD5 modelling through ANFIS.

Fluorescent Pseudomonads strains were considered as plant growth promoting bacteria. They exhibited antagonistic activities against phytopathogens and showed bio-fertilizing properties. The strain Pseudomonas fluorescens PsWw128, isolated from wastewater, can use the pentachlorophenol (PCP) as the sole source of carbon and energy. High-performance liquid chromatography (HPLC) and spectrophotometric methods were used to follow the PCP degradation and biomass PsWw128 formation. However, the removal efficiency of PCP was highly significant. Thus, PsWw128 was able to degrade more than 99% of PCP when this isolate was grown under a high concentration of PCP (250 mg L–1) in a mineral salts medium (MSM). The simultaneous utilization of glucose and PCP indicates the diauxic growth pattern of PsWw128. PCP addition (100 mg L–1) in the growth medium can contribute to a decrease of the antibiotic susceptibility, and increase the biofilm development. In the presence of the toxic pollutant PCP (100, 200 and 250 mg L–1), the antibiotic sensitivity showed a decrease concerning the seven antibiotics tested. Furthermore, the biofilm formation appeared very low with OD600 = 0.075 in the Brain infusion broth supplemented with 25% of glucose, and developed a significant growth with an OD600 = 1.809 in the MSM supplemented with 250 mg L–1 of PCP.

Ultraviolet (UV) light water treatment reactors are commonly used in both wastewater and drinking water disinfection. UV technology can effectively inactivate a large number of pathogens at low UV doses, however adenovirus requires a substantially higher dose than most pathogens of interest. In order to meet adenovirus inactivation requirements, UV reactors are often placed in series and the total inactivation is calculated as the sum of the reactors' individual UV doses. In this paper, it is shown that this simple summation treatment of UV dose may be acceptable. A parameter called the reactor additivity factor is introduced to properly characterize the interaction between UV reactors in series. Three types of UV reactors are modelled using computational fluid dynamics, and their RAFs are computed. The validity of reactor additivity in practice in wastewater and drinking water systems is discussed.

Cellular adenosine triphosphate (cATP™) may be used to characterize the biological degradation activity within the anaerobic and aerobic wastewater treatment systems. The feasibility of using cATP™ as a process monitoring parameter for an anaerobic membrane bioreactor was evaluated. Results obtained from batch respirometric anaerobic treatability studies and a continuous sludge-bed anaerobic membrane bioreactor (SB-AnMBR) treating prehydrolysis liquor were examined. Both studies were conducted at an operating temperature of 35 °C. The batch studies indicated that the indirect activity measurements, such as the methane production rate correlated well with cATP™. The cATP™ content of the SB-AnMBR responded to changes in total amount of degraded chemical oxygen demand (COD) and methane produced with correlation coefficient of 0.91 and 0.80, respectively. In contrast, cATP™ was not well correlated to mixed liquor volatile suspended solids with correlation coefficient of 0.52. The values of cATP™/CODremoved ratio and active biomass ratio (ABR™) indicated that the increase in cATP™ value might be a result of increased biodegradation activity in the SB-AnMBR system.

Sequencing batch reactor (SBR) was assessed for direct co-treatment of old landfill leachate and municipal wastewater for chemical oxygen demand (COD), nutrients and turbidity removal. Nitrogen removal was achieved by sequential nitrification and denitrification under post-anoxic conditions. Initially, SBR operating conditions were optimized by varying hydraulic retention time (HRT) at 20% (v/v) landfill leachate concentration, and results showed that 6 d HRT was suitable for co-treatment. SBR performance was assessed in terms of COD, ammonia, nitrate, phosphate, and turbidity removal efficiency. pH, mixed liquor suspended solids, mixed liquor volatile suspended solids (MLVSS), and sludge volume index were monitored to evaluate stability of SBR. MLVSS indicated that biomass was able to grow even at higher concentrations of old landfill leachate. Ammonia and nitrate removal efficiency was more than 93% and 83%, respectively, whereas COD reduction was in the range of 60–70%. Phosphate and turbidity removal efficiency was 80% and 83%, respectively. Microbial growth kinetic parameters indicated that there was no inhibition of biomass growth up to 20% landfill leachate. The results highlighted that SBR can be used as an initial step for direct co-treatment of landfill leachate and municipal wastewater.

Evaluation of microbial water quality is commonly based on monitoring populations of fecal indicator organisms (FIO) such as Escherichia coli (EC) and enterococci (ENT). The occurrence of elevated FIO concentrations in surface waters after storm events is well documented and has been attributed to runoff and sediment resuspension. The reasons for FIO concentration variation under baseflow conditions are less clear. The objective of this study was to quantify the variability of EC and ENT in two small streams running through agricultural land use areas. FIO concentrations were measured at upstream and downstream locations under baseflow conditions. Concentrations were not significantly different along cross-sections of the streams. Diurnal concentration trends were observed at each of the sampling locations. Significant differences in concentrations between upstream and downstream locations were noted for both creeks during baseflow periods when no runoff or sediment resuspension occurred. A hypothetical explanation is that indicator organisms are released from sediments during baseflow conditions due to the effect of groundwater influx into streams or due to the motility of indicator organisms. If confirmed, this hypothesis may affect our understanding of the role of sediments in the microbial quality of surface waters.

Currently, there is no standard bench-scale dead-end ultrafiltration (UF) testing system. The aim of the present study was to design and build a bench-scale hollow fiber UF system to assess the impact of operational parameters on membrane performance and fouling. A bench-scale hollow fiber UF system was built to operate at a constant flux (±2% of the set-point flux) and included automated backwash cycles. The development of the bench-scale system showed that it is very difficult to maintain a constant flux during the first minute of the filtration cycles, that digital flow meters are problematic, and that the volume of the backwash waste lines should be minimized. The system was evaluated with Ottawa River water, which has a relatively high hydrophobic natural organic matter content and is typical of Northern Canadian waters. The testing using different permeate fluxes, filtration cycle duration and backwash cycle duration showed that this system mimics the performance of larger systems and may be used to assess the impact of operating conditions on membrane fouling and alternative pretreatment options. Modeling the first, middle, and last filtration cycles of the six runs using single and dual blocking mechanisms yielded inconsistent results regarding the controlling fouling mechanisms.

This paper comparatively assessed the effectiveness of potable water filtration methods, commonly used in the hinterlands in some Ghanaian communities. Physico-chemical and microbiological analysis were carried out on pond, dam and river water samples, using spectrophotometric, pour plate count and the most probable number (MPN) methods. For the unfiltered water samples the total dissolved solids (TDS) and colour were the only parameters with values within recommended standards. The other parameters, total suspended solids (TSS), turbidity, total coliforms and bacterial counts levels were above their standard recommended values. All the filtration methods showed reduction in the levels or better accepted values of the physico-chemical and microbiological parameters. The ceramic filters and the household sand filters showed outstanding results, with all analysed parameters being within the acceptable standards levels. These two methods could be promoted for use to treat untreated drinking water. It is envisaged that a combination of a number of these methods would produce even better results, especially when agents such as alum and activated carbon are included. Follow-up research in this regard is therefore recommended.