Biologically-treated Wastewater Research Articles

Application of (V)UV/O3 technology for post-treatment of biologically treated wastewater: A pilot-scale study

For the first time, high energy VUV photons and generation of O3 by (V)UV lamps were applied together for removal of active pharmaceutical ingredients (APIs) from biologically treated wastewater (BTWW) in pilot-scale. The core of the pilot container unit was a photoreactor assembly consisting of six photoreactors, each containing a low-pressure Hg lamp (UV dose of 1.2 J/cm2 and 6.6 J/cm2 at 185 nm and 254 nm, respectively). BTWW was irradiated (4.75 min residence time) by (V)UV light in presence of in situ photochemically generated O3 from coolant air of the lamps. Experiments were conducted at the site of two wastewater treatment plants. Out of seven target APIs (namely carbamazepine, ciprofloxacin, clarithromycin, diclofenac, metoprolol, sitagliptin, and sulfamethoxazole), 80–100% removal was accomplished for five and 40–80% for two compounds. Two degradation products of carbamazepine were detected. Degradation products of other target compounds were not found. The applied O3 dose was 30–45 μg O3/mg dissolved organic carbon. Inactivation of up to log-4.8, log-4.5 and log-3.8 could be achieved for total coliform, Escherichia coli and Enterococcus faecalis, respectively. SOS Chromotest indicated no genotoxicity nor acute toxicity. Generation of neither NH4+, NO2− nor NO3− was observed during post-treatment. Electric energy per order values were calculated for the first time for (V)UV/O3 treatment in BTWW with a median value of 1.5 kWh/m3. This technology can be proposed for post-treatment of BTWWs of small settlements or livestock farms to degrade micropollutants before water discharge or for production of irrigation water. Further studies are essential in pilot-scale for other applications.

Elucidating distinct oxidative stress management, nutrient acquisition and yield responses of Pisum sativum L. fertigated with diluted and treated wastewater

Fertigation of crops with untreated wastewater predominates in developing countries. Use of wastewater for crop irrigation poses a potential risk of food chain poisoning with toxicants. However, direct and indirect interaction of wastewater with soil properties and crop productivity has been rarely investigated. The current work was, therefore, planned to quantify the impact of canal water, biologically treated and untreated wastewater on soil properties, growth, biochemical, nutrient turnover and yield of pea (Pisum sativum L.) plants. Seeds of P. sativum were sown in soil filled pots irrigated with five different water types [canal water (CW), biologically treated wastewater (BTW), 50%, 75% and 100% wastewater (WW50, WW75 and WW100)]. The plant samples were collected after 35 days for biochemical analysis, while yield parameters were recorded at maturity. The results revealed a significantly higher growth and yield of pea plants irrigated with BTW followed by WW50 and CW irrigated plants as compared to other wastewater treatment types. Application of untreated wastewater (WW75 and WW100) resulted in stunted growth due to decrease in total chlorophylls, carotenoids, activities of SOD and POD enzymes, and increase in lipid peroxidation (MDA and H2O2) as compared to CW, BTW, and WW50. Pre- and post-harvest soil analysis revealed that application of concentrated wastewater caused soil alkalinization and subsequently limited the nutrient absorption by P. sativum plants. Growth enhancement of P. sativum under BTW might be a direct consequence of balanced accumulation of nutrients owing to alteration of soil properties. It was concluded that wastewater must be treated biologically or diluted with 50% of fresh canal water before application to agricultural fields in order to maintain soil nutrient level and sustainable crop productivity in the areas with less availability of fresh canal water.

Activated sludge process faults diagnosis based on an improved particle filter algorithm

Maintaining the discharge standards of biologically-treated wastewater is essential in order to protect receiving water bodies from secondary pollution. If unexpected faults happen in an activated sludge process that is used as biological treatment, it would affect the quality of the receiving water body. Thus, in this paper, an improved particle filter (PF) algorithm, based on a variable frequency mutation (VFM) strategy is proposed for the process faults diagnosis. This is inspired by the frequency conversion for energy-saving application in the industrial process; an adaptive frequency conversion operator has been incorporated into the mutation operation of immune algorithm to reduce the system operating costs. Then, the resampling process of PF algorithm was replaced by particle mutation based on the previously calculated information for securing the diversity and the effectiveness of the particle; lastly, a VFM-based PF algorithm for system states estimation and fault diagnosis was established. This algorithm not only effectively increases the adaptability of the particle to changes of the system state, but also conductively solves the problems of the degeneracy in the traditional PF algorithm and the diversity weakening caused by resampling operation. Simulation results show that the algorithm can effectively improve the estimation accuracy of the nonlinear system states. The application results of faults diagnosis in the activated sludge process show that it can accurately diagnose the occurrence of faults. Therefore, the proposed method has great practical significance in wastewater treatment plants to avoid problems caused by unexpected faults.

Effects of UV disinfection on phenotypes and genotypes of antibiotic-resistant bacteria in secondary effluent from a municipal wastewater treatment plant

To elucidate the effects of UV disinfection on antibiotic resistance in biologically-treated wastewater, we investigated the antibiotic resistance profiles, species of cultivable heterotrophic bacteria, and antibiotic-resistance genes (ARGs) in antibiotic-resistant bacteria before and after treatment. UV disinfection greatly changed the bacterial community structure and the antibiotic resistance in wastewater. The antibiotic resistance in wastewater samples was strongly associated with the bacterial community. The proportions of Gram-positive bacteria gradually increased with increasing UV fluence. The proportions of bacteria resistant to cephalexin, penicillin, and vancomycin all greatly decreased after UV treatment in both sampling events (July 2018 and January 2019), and those for bacteria resistant to ofloxacin, ciprofloxacin, and sulfadiazine increased, resulting from the alternative antibiotic resistance profiles among different genera. UV disinfection induced the selection of multi-antibiotic resistant (MAR) bacteria. For example, the MAR indices of Aeromonas, the dominant genus during the treatments, were significantly increased after UV irradiation (P < 0.05). The MAR index was also markedly increased (P < 0.05) at a fluence of 5 mJ/cm2 in both events. In UV10 treatment, the bacterial community structure was greatly changed. The genera with relatively low MAR indices replaced that with high MAR indices, and became the dominant genera. As a result, the MAR indices of treated samples showed a decreased trend after 10 mJ/cm2 UV irradiation. The detection frequencies of ARGs located on the chromosome varied mainly due to the evolution of the microbial community. The occurrence of ARGs (tetA, tetC, tetM, tetW, tetX, and sul1) located on plasmid DNA decreased after UV disinfection, and the average detection frequencies of tet and sul genes decreased by 15% and 6%, respectively (P < 0.05). Generally speaking, the effect of UV disinfection on the enrichment of antibiotic resistance is limited in this study, and horizontal gene transfer via the plasmids in surviving bacteria might be impaired due to the decreased abundance of ARGs on the plasmids.

Combined toxicity of graphene oxide and wastewater to the green algaChlamydomonas reinhardtii

The toxic action of graphene oxide (GO) and the micropollutants contained in a biologically-treated wastewater were studied alone and in combination.

Prioritizing Unknown Transformation Products from Biologically-Treated Wastewater Using High-Resolution Mass Spectrometry, Multivariate Statistics, and Metabolic Logic.

Incomplete micropollutant elimination in wastewater treatment plants (WWTPs) results in transformation products (TPs) that are released into the environment. Improvements in analytical technologies have allowed researchers to identify several TPs from specific micropollutants but an overall picture of nontarget TPs is missing. In this study, we addressed this challenge by applying multivariate statistics to data collected with liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) and subsequent tandem HRMS (MS/MS) in order to characterize peaks detected in the influent and effluent of a WWTP. Known biotransformation reactions were used to link potential parent compounds and TPs, while the structural similarity of these pairs hypothesized by MS/MS similarity was used for further prioritization. The methodology was validated with a set of spiked compounds, which included 25 parent/TP pairs for which analytical standards were available. This procedure was then applied to nontarget data, and 20 potential parent and TP pairs were selected for identification. In summary, primarily a surfactant homologue series, with associated TPs, was detected. Some obstacles still remain, including spectral interferences from coeluting compounds and identification of TPs, whose structures are less likely to be present in compound databases. The workflow was developed using openly accessible tools and, after parameter adjustment, could be applied to any data set with before and after information about various biological or chemical processes.

Biological Treatment of Textile Wastewater and Its Re-Use in Irrigation: Encouraging Water Efficiency and Sustainable Development

The present study focused on the isolation of potential bacteria from contaminated soil of textile industries and subsequent employment of those organisms in treatment of textile waste-water. Wastewater was treated by novel isolates and the biologically treated wastewater was used for the irrigation (phytotoxicity evaluation) of two important edible crop plants (Brassica nigra and Cyamopsis tetragonolobus). For this, plants were grouped as I, II, III and IV that received the tap water, raw effluent, chemically treated and biologically treated wastewater respectively. 46 bacterial isolates were obtained and optimization of parameters revealed that one strain, namely UBL-27 (Comamonas sp. UBL 27) decolorized the wastewater to a max. of 80% in static (anoxic) condition at pH 8 in 24 hours at 32oC. There was a remarkable performance in the germination percentage under biologically-treated wastewater to about 83.6% when compared to that of Control Group producing 92.9%. In contrast to this, the germination % was significantly too low (p≤0.05) in the other cases with the raw wastewater and chemically treated wastewater. The wastewater had marked effect on the growth of the Brassica nigra, the height of the plant was higher in the biologically treated effluent (11.2 ± 0.4 cm) and control group (12.1±0.2) than Group II (8.9±.17 cm) and Group III (9±0.2 cm). Weight of the plant was 1.95±0.35 g and 1.68±0.47 g in Group I and Group IV. It was significantly lower in case of Group II and Group III. In Cyamopsis tetragonolobus, heights of the plant among the four groups at the end of 80 days were 102.3±3.4, 52±7.6, 45.3±4.9 and 92.8±5 cm respectively. Similarly, no. of leaves/plant among the four groups was 49.2±3.2, 26.8±4.5, 32±2.4 and 47±4.5. Total yield of the plant under the experimental area for Group I was 3.15±0.09 kg while that of the Group IV was 2.92±0.09 kg. The yield was significantly lower in the Group II and III such as 1.67±0.17 kg and 2.06±0.22 kg respectively. To consolidate, the raw effluent has decreased the yield by more than 45% (p≤0.05) while that of the chemically treated group by more than 30%. Though, biologically treated wastewater may not be absolutely fit for drinking purposes or for recycling in dyeing processes, it is proved from this, that the eco-friendly alternative can be used for the irrigation purposes beside abatement of water and soil pollution.

Effect of ammonia on the formation of THMs and HAAs in secondary effluent chlorination

Recent studies have reported that genotoxicity is increased significantly in wastewater with a high ammonia concentration after chlorination. Thus, this paper studied the effect of ammonia on the formation and speciation of trihalomethanes (THMs) and haloacetic acids (HAAs) during the chlorination of two different biologically-treated wastewater samples from different sources. The formation of THM species was suppressed with increasing ammonia concentration in both samples, but the effect of ammonia concentration on the formation of HAA species (as dichloroacetic, bromochloroacetic, and bromodichloroacetic acid) was quite different. The yields of dihalogenated species occupied the greatest fractions of the total HAAs (over 46%) in both wastewater samples under the experiment scope. However, regarding the distribution of mono-, di-, and trihalogenated species in HAAs, there were discrepancies between the wastewater samples from different sources. The bromine incorporation factors n(Br) and n′(Br), as a function of ammonia concentration, were influenced by the Br −/N mass ratio in wastewater chlorination, and were constant when the Br −/N mass ratio was lower than 0.003 (or 0.53 μM mM −1) due to the low concentrations of bromide ions.

The effects of treated domestic sewage on three organs (gills, kidney, liver) of brown trout ( Salmo trutta)

In an experiment extending over approx. 3 months, brown trout ( Salmo trutta) were exposed to dilutions of biologically-treated wastewater (13, 24 and 42%) from a large sewage plant. The two higher concentrations caused a sequence of histological changes in the kidney and, after some delay, in the liver as well. No effects were detectable in the gills however. In all dilutions of the biologically-treated sewage, external injury of the fish was rapidly followed by fungal infection. Furthermore, kidney changes similar to those seen in the experiment were also observed in brown trout and rainbow trout ( Oncorhynchus mykiss) caught downstream of the point at which the treated effluents from the sewage plant entered the River Inn. The pathogenic effects of ammonia and nitrite in the treated sewage are discussed.