Effluent Research Articles

Unveiling the critical role of overlooked consumer protist-bacteria interactions in antibiotic resistance gene dissemination in urban sewage systems

Antibiotic resistance genes (ARGs) are emerging contaminants of significant concern due to their role in facilitating the spread of antibiotic resistance, especially high-risk ARGs, which are characterized by high human accessibility, gene mobility, pathogenicity, and clinical availability. Studies have shown that cross-domain interactions, such as those between consumer protists (consumers) and bacteria, can influence bacterial diversity, distribution, and function through top-down power. The consumers-bacteria interactions may also affect the occurrence and distribution of ARGs, yet this has been scarcely explored in field investigations. We conducted a city-scale investigation of ARGs, protists, and bacterial communities across each unit of the urban sewage system (USS), including 49 sewage pumping stations (SW), as well as influent (IF), activated sludge (AS), and effluent (EF) from seven wastewater treatment plants. Interestingly, consumers-bacteria interactions, as indicated by indices of bipartite relevance networks (i.e., connectedness and cohesion), increased from SW and IF to AS and EF. Structural equation modelling (SEM) revealed that consumers-bacteria interactions had a greater influence on the abundance of total ARGs and high-risk ARGs than seasonal or environmental factors. Notably, the total effects of consumers-bacteria interactions in SEM were significant (P < 0.05) and comparable in both IF and EF, even with the decrease in ARG abundance from IF to EF. This suggests a potential risk of ARG spread to the environment, facilitated by consumer protists in the EF. Additionally, the relevance network also demonstrated an increasing trend in the relationships between consumer protists and potential hosts of high-risk ARGs from raw sewage (SW and IF) to AS and EF. Overall, this study emphasizes the importance of integrating multitrophic microbial interactions to better understand and mitigate the dissemination of ARGs in sewage systems.

Physical-chemical and nutritional parameters of liquid porcine effluent from a biodigester supplemented with a lagoon system.

Objetive. Determining the concentration of physical-chemical and nutritional parameters of the wastewater derived from a biodigester complemented with lagoon train. Metodology. A study was carried out in the CEAJAL livestock production module, 12 gestating sows, fresh solid excreta was collected manually (shovel and wheelbarrow), the lagoon-type biodigester was fed daily with two levels of organic load (CO), CO5% and CO15%. The biogas and wastewater were evaluated in four periods of 40 days each. The Influent washing water (INF) entered the biodigester, then the liquid effluent (EFL) was subjected to complementary treatment of EFL stabilization pits, Pit 2, Pit 3 and Pit 4, determining physical-chemical parameters such as TSS, pH, CTE and COD, and nutritional parameters such as NT and FT. The data were analyzed using descriptive and differential statistics. Results. The methane content in the biogas was 59.8%; CO5% and 60.2%; CO15% (p&gt;0.05). The physical-chemical parameters of INF such as SST ml/L was 67.4; CO5% and 81.3; CO15%. EFL was 23.2 and 48.0, respectively, in COD ml/L of INF was 738.7; CO5% and 1807.7; CO15%. EFL was 1444.2 and 2522.5, respectively, in NT ml/L of INF was 128.3; CO5% and 111.9; CO15%. EFL was 436.9 and 554.6, respectively. Conclusions. Despite a lower CO, methane production is in the normal range and the physical-chemical and nutritional parameters of the wastewater as it passes into stabilization lagoons can be taken as a reference to determine the CO that should enter to the biodigester with the purpose of providing complementary treatment of the wastewater generated in pig farms.

Sustainable Ceramic Glaze Development from Coal Power Plant Water Treatment Sludge: A Customer-Oriented Approach Using Delphi Method, QFD, and Mixture Design

This research delves into the sustainable utilization of waste materials, particularly chemical sludges from coal power plant water treatment processes, in ceramic glaze development. The study background underscores the growing interest in repurposing industrial waste for sustainability in the ceramics industry. To address this, this study employs innovative methods like the Delphi method and Quality Function Deployment (QFD) to understand customer needs and guide product development. The next step will be to design an experiment to find the optimization point of the mixture of chemical sludge, silica, and soda feldspar to obtain a prototype as desired from QFD. The experimental investigations in this study highlight that resistance to cracking is a crucial factor in glaze formulations. An analysis revealed that a formulation containing 15% sludge, 52% soda feldspar, and 22% silica emerged as the optimal combination for further development. The results indicate that the prototype holds promise for future development, as demonstrated by cracking tests accelerated in an autoclave and analyzed using image processing. These findings contribute to advancing sustainable practices in ceramics, aligning with broader goals of waste minimization, circular economy principles, and resource efficiency.

Bioinspired, Carbohydrate-Containing Polymers Efficiently and Reversibly Sequester Heavy Metals.

Water scarcity and heavy metal pollution are significant challenges in today's industrialized world. Conventional heavy metal remediation methods are often inefficient and energy-intensive, and produce chemical sludge. To address these issues, we developed a bioinspired, carbohydrate-containing polymer system for efficient and selective heavy metal removal. Using ring opening metathesis polymerization, we synthesized polymers bearing amphiphilic glucuronate side chains capable of selectively binding heavy metal cations in mixed media. In samples containing high concentrations of heavy metals (>550 ppb), these polymers rapidly form a filterable precipitate upon metal capture, reducing the concentration of cation to <1.5 ppb within 3 min, as measured by inductively coupled plasma mass spectrometry. This system effectively removes cadmium ions from highly contaminated solutions to levels below the Agency for Toxic Substances and Disease Registry limit for Cd2+ in drinking water and selectively removes both Cd2+ and Pb2+ from lake water spiked with trace amounts of metal. Acidification triggers protonation of the glucuronate groups, releasing the heavy metals and resolubilizing the polymer. This capture-and-release process can be repeated over multiple cycles without loss of binding capacity. As such, this study introduces a novel class of recyclable materials with pH-responsive properties, offering potential for applications in water remediation and beyond.

High-carbon-content biochar from chemical manufacturing plant sludge for effective removal of ciprofloxacin from aqueous media

Biochar is considered a promising biosorbent for harmful organic pollutants in aqueous media. However, only a limited number of biochars derived from industrial sludges have been utilized due to their problematic high ash content and heavy metal leaching. In this study, a highly effective biochar was prepared as a superabsorbent for ciprofloxacin (CIP) from chemical manufacturing plant sludge via K2CO3-activated pyrolysis, and its CIP removal behavior was evaluated. Unlike sewage sludge, chemical manufacturing plant sludge contains low SiO2, resulting in an ultra-pure carbon (95.4%) based biochar with almost negligible ash content. As the pyrolysis temperature increased from 400 to 800 °C, the ordered graphitic carbon structure transformed into an amorphous carbon phase, and most oxygen-containing groups disappeared. However, the pore size significantly decreased to ∼4.5 nm due to the corrosive carbon volatilization caused by K2CO3, resulting in an extremely large surface area of 2331.8 m2/g. Based on its large surface area and porous carbon structure, the activated biochar at 800 °C (CAB-800) exhibited an outstanding CIP adsorption capacity of 555.56 mg/g. The CIP adsorption isotherm, kinetic, and thermodynamic studies were systematically investigated. The CIP adsorption on CAB-800 was mainly attributed to π-π interactions and hydrogen bond formation, with electrostatic interactions partially contributing to the adsorption reaction. From pH 2 to 12, CAB-800 showed an excellent CIP adsorption capacity of over 316.7 mg/g, with adsorption favored under acidic conditions. Except for HCO3− and CO32−, the presence of anions and humic acids did not significantly affect CIP adsorption capacity. These results demonstrate that biochar produced from chemical manufacturing industry sludge via K2CO3 activation is a highly feasible material for the removal of CIP from aqueous media.

Resource utilization of chemical excess sludge to produce metal–organic framework with outstanding Fenton-like performance for sulfamethoxazole removal

The safe disposal of excess sludge has emerged as a pressing concern due to its high toxicity, stemming from a diverse array of components such as viruses, heavy metals, and polycyclic aromatic hydrocarbons. Herein, this study explored the feasibility of using extracted Fe from the excess sludge to produce metal–organic frameworks (MOFs). Specifically, MIL-100 and MIL-88A were successfully synthesized by coordinating 1,3,5-benzene tricarboxylic acid and fumaric acid with excess sludge-retained iron under wide reaction conditions. The purity of the resulting MOFs was ascertained through elemental analysis. Moreover, the synthesized MOFs demonstrated outstanding electrocatalytic performance in the degradation of sulfamethoxazole (SMX). Compared to the control group without catalysts, the addition of MIL-100-170-6 (30 mg) led to a remarkable enhancement in SMX removal efficiency, increasing it to 99.9 % from 58.3 %. This enhancement was accompanied by a substantial increase in the corresponding kinetic constant (kobs) values, reaching 0.1137 min−1, representing an 8.1-fold improvement over the blank group. The catalytic mechanism was further evaluated via quenching experiments and electron paramagnetic resonance (EPR) spectroscopy, suggesting that the •OH and O2•− radicals were responsible for SMX degradation. Economic analysis of MOF materials preparation revealed that the use of excess sludge-retained Fe can significantly reduce the cost of MOFs. Thus, it is believed that our work provides a low-cost and sustainable approach for converting excess sludge into functional MOFs, which not merely facilitates the recycling of excess sludge-retained Fe, but also provides functional materials with outstanding performance for the degradation of SMX.

Economic evaluation of submerged anaerobic hybrid membrane bioreactor operating at mesophilic temperature.

A laboratory-scale mesophilic submerged anaerobic hybrid membrane bioreactor (An-HMBR) was operated for 270days for the treatment of high-strength synthetic wastewater at different hydraulic retention times (HRTs) (3days, 2days, 1day, and 0.5days). Chemical oxygen demand (COD) removal efficiency of 92% was obtained with methane yield rate of 0.18 LCH4/g CODremoval at 1-day HRT. The results of lab scale reactor at 1-day HRT were utilized for upscaling and cost analysis. Cost analysis revealed that the total capital cost comprised tank system (48%), membrane cost (32%), screen and PUF sponge (5% each), PLCs (4%), liquid pumps (3%), and others (2%). The operational cost comprised chemical cost (46%), pumping energy (42%), and sludge disposal (12%). The results revealed that the tank and heating costs accounted for the largest fraction of the total life cycle cost for full-scale An-HMBR. The heating cost can be compensated by gas recovery. Sensitivity analysis revealed that the interest rates, influent flow, and membrane flux were the most crucial parameters which affected the total cost of An-HMBR.

Investigations in pyrolysis kinetics of sludges of different origins: chemical sludge, biological sludge and oily sludge

Investigations in pyrolysis kinetics of sludges of different origins: chemical sludge, biological sludge and oily sludge

Carbon performance analysis of upgraded wastewater treatment plants in key control areas of the Ziya River Basin in China

Wastewater treatment plants (WWTPs) are one of the largest sources of greenhouse gas (GHG) emissions, and they are also one of the largest energy consumption industries in urban systems. With the progression of upgrading and standard-rising, WWTPs both directly and indirectly increase carbon emissions from the increased investments in facilities and usages in electricity as well as chemical agents. Here, we collected operational data from 15 WWTPs in the key control areas of the Ziya River Basin in North China and accounted for the changes in carbon performance at different technical upgrade methods. Results showed that the average carbon emission performance increased by 0.487 kg CO2/m3 after the upgrade. Carbon emissions from electricity consumption, chemical usage, biochemical process and sludge treatment accounted for 42%, 17%, 24%, and 17% of the total improvement in carbon emission performance, respectively. Reducing energy consumption, regulating chemical use and sludge comprehensive utilization are the key to carbon emission reduction. It further proposes that the development of wastewater treatment discharge standards should fully consider the comprehensive utilization of water quality classification. Regions with favorable natural conditions should make full use of their advantages by adopting economically feasible, low-energy-consuming technologies such as constructed wetlands, which offer carbon sequestration and landscaping benefits. This study provides guidance on the selection of technological pathways for pollution reduction and carbon mitigation in the wastewater treatment industry and on achieving sustainable water resource utilization.

The Many‐Chemicals Problem of Systems Chemistry

AbstractAn E. coli cell contains ~2500 different chemicals which combine into an ordered biochemical reaction network out of which emerges a living system. A chemist taking 2500 different chemicals from a laboratory chemical cabinet and combining them together will likely cause an explosive disaster and produce an intractable chemical sludge. Systems Chemistry aspires to construct systems whose complexity rivals that of life. However, to do this we will need to learn how to combine hundreds or thousands of different chemicals together to form a functional system without descending into a disordered chemical sludge. This is the Many‐Chemicals Problem of Systems Chemistry. I explore a key strategy life employs to overcome this challenge. Namely, the combination of kinetically stable and thermodynamically activated molecules (e. g. ATP) with enzyme catalysts (e. g. histidine kinases). I suggest how the strategy could have begun at the origin of life. Finally, I assess the implications of this strategy for Systems Chemistry and how it will enable systems chemists to construct systems whose complexity rivals that of life.

Pilot-scale phosphorus recovery from biogas slurry to produce battery-grade FePO4: Chemical enhanced primary treatment coupled adsorption process

Recovering phosphorus (P) from wastewater was expected to bring win–win profits for environmental protection and clean energy industries. Ferric phosphate (FePO4) was a key raw material for lithium-ion battery production for new energy vehicles, which was a more valuable and promising product for recovering P from wastewater. There were challenges in recovering high-purity FePO4 from wastewater with complex components, especially in achieving large-scale recovery. Here, a pilot-scale platform, the Chemical Enhanced Primary Treatment (CEPT) coupled Fe@aminated-polyacrylonitrile (Fe-NH2-PAN) adsorption, was established for recovering battery-grade FePO4 from biogas slurry. The platform stably removed over 80% of PO43− from biogas slurry during long-term operation, the removed PO43− was enriched in chemical sludge and Fe-NH2-PAN, and then was leached into H2SO4 solution. FePO4 crystal was successfully recovered from the leaching solution (822.35 ± 15.91 mg/L PO43−) with a recovery rate of over 75%. Importantly, the lithium-ion battery prepared from recovered FePO4 exhibited excellent and stable electrochemical performance (with stable discharge specific capacity of 100.4–106.7 mAh/g at 1.0 C). This study provides a new path for large-scale P recovery in WWTPs.

Optimization of chemistry and process parameters for control of intermetallic formation in Mg sludges

Intermetallic formation in sludge during magnesium (Mg) melting, holding and high pressure die casting practices is a very important issue. But, very often it is overlooked by academia, original equipment manufacturers (OEM), metal ingot producers and even die casters. The aim of this study was to minimize the intermetallic formation in Mg sludge via the optimization of the chemistry and process parameters. The Al8Mn5 intermetallic particles were identified by the microstructure analysis based on the Al and Mn ratio. The design of experiment (DOE) technique, Taguchi method, was employed to minimize the intermetallic formation in the sludge of Mg alloys with various chemical compositions of Al, Mn, Fe, and different process parameters, holding temperature and holding time. The sludge yield (SY) and intermetallic size (IS) was selected as two responses. The optimum combination of the levels in terms of minimizing the intermetallic formation were 9 wt.% Al, 0.15 wt.%Mn, 0.001 wt.% (10 ppm) Fe, 690 °C for the holding temperature and holding at 30 mins for the holding time, respectively. The best combination for smallest intermetallic size were 9 wt.% Al, 0.15 wt.%Mn, 0.001 wt.% (10 ppm) Fe, 630 °C for the holding temperature and holding at 60 mins for the holding time, respectively. Three groups of sludge factors, Chemical Sludge (CSF), Physical Sludge (PSF) and Comprehensive Sludge Factors (and CPSF) were established for prediction of sludge yields and intermetallic sizes in Al-containing Mg alloys. The CPSF with five independent variables including both chemical elements and process parameters gave high accuracy in prediction, as the prediction of the PSF with only the two processing parameters of the melt holding temperature and time showed a relatively large deviation from the experimental data. The Chemical Sludge Factor was primarily designed for small ingot producers and die casters with a limited melting and holding capacity, of which process parameters could be fixed easily. The Physical Sludge Factor could be used for mass production with a single type of Mg alloy, in which the chemistry fluctuation might be negligible. In large Mg casting suppliers with multiple melting and holding furnaces and a number of Mg alloys in production, the Comprehensive Sludge Factor should be implemented to diminish the sludge formation.

Synchronous in-situ sludge reduction and enhanced denitrification through improving electron transfer during endogenous metabolisms with Fe(Ⅱ) addition

The creation of large amounts of excess sludge and residual nitrogen are critical issues in wastewater biotreatment. This study introduced Fe(II) into an oligotrophic anaerobic reactor (OARFe) that was implemented to modify an anoxic-oxic process to motivate in-situ sludge reduction and enhance denitrification under an effective electron shuttle among organic matter, nitrogen, and Fe. The addition of 15 mg L−1 Fe(II) resulted in a sludge reduction efficiency reached 32.0% with a decreased effluent nitrate concentration of 33.3%. This was mostly attributed to the electron transfer from Fe(II) to organic matters and nitrogen species in OARFe. The participation of Fe(II) led to the upregulation of Geothrix and Terrimonas, which caused active organic matter hydrolysis and cell lysis to stimulate the release of extracellular polymeric substances (EPS) and substance transfer between each layer of EPS. The higher utilization of released bioavailable dissolved organic matter improved endogenous denitrification, which can be combined with iron autotrophic denitrification to realize multiple electron donor-based nitrogen removal pathways, resulting in an increased nitrate removal rate of 58.2% in the absence of external carbon sources. These functional bacteria associated with the transformation of nitrogen and carbon and cycling between ferrous and ferric ions were enriched in OARFe, which contributed to efficient electron transport occurred both inside and outside the cell and increased 2,3,5-triphenyltetrazolium chloride electronic transport system activity by 46.9%. This contributed to the potential operational costs of chemical addition and sludge disposal of Fe-AO being 1.9 times lower than those of conventional A2O processes. These results imply that the addition of ferrous ions to an oligotrophic anaerobic zone for wastewater treatment has the potential for low-cost pollution control.

Volatile fatty acids production from kitchen waste slurry using anaerobic membrane bioreactor via alkaline fermentation with high salinity: Evaluation on process performance and microbial succession

In this study, a pilot-scale anaerobic membrane bioreactor (AnMBR) was developed to continuously produce volatile fatty acids (VFAs) from kitchen waste slurry under an alkaline condition. The alkaline fermentation effectively suppressed methanogenesis, thus achieving high VFAs production of 60.3 g/L. Acetic acid, propionic acid, and butyric acid accounted for over 95.0 % of the total VFAs. The VFAs yield, productivity, and chemical oxygen demand (COD) recovery efficiency reached 0.5 g/g-CODinfluent, 6.0 kg/m3/d, and 62.8 %, respectively. Moreover, the CODVFAs/CODeffluent ratio exceeded 96.0 %, and the CODVFAs/NH3-N ratio through ammonia distillation reached up to 192.5. The microbial community was reshaped during the alkaline fermentation with increasing salinity. The membrane fouling of the AnMBR was alleviated by chemical cleaning and sludge discharge, and membrane modules displayed a sustained filtration performance. In conclusion, this study demonstrated that high-quality VFAs could be efficiently produced from kitchen waste slurry using an AnMBR process via alkaline fermentation.

Experimental support for a sustainable treatment strategy of acrylic fiber dyeing wastewater

AbstractThe study intended to devise a sustainable treatment scheme for acrylic fiber dyeing process effluents, which significantly differ from other textile plant wastewaters. The necessary experimental support was generated from a set of tests conducted on the wastewater of a plant operation, focused solely on acrylic fiber dyeing. Related experiments involved effluent characterization, biological treatability, and chemical settling/oxidation performed on raw and bio‐treated effluent, as pre‐treatment and/or polishing steps. A total COD level of 910 mg/L with a 70% soluble ratio, low total N and P contents below 10 mg/L, a detergent content of 50 mg/L and a dark/black color of 1150 Pt‐Co unit defined the average properties of the raw plant effluent. Experimental support indicated that activated sludge operation at a sludge age level above 25 d, remained insufficient as it could only provide an effluent with a soluble COD level above 150 mg/L, a biomass escape in the range of 40 to 100 mg/L and with an intense dark color. A similar experimental template, including chemical settling, chemical oxidation by NaOCl and combination of the two processes, was tested as pre‐treatment and a polishing step after biological treatment. Pre‐treatment, although with some benefit to remove toxic and inhibitory compounds, proved to be highly costly, due to excessive chemical usage and sludge generation for a sustainable, cost‐effective approach. The sequence of chemical oxidation and settling steps implemented as a polishing stage was quite effective as it secured complete color removal, a major source of concern for the selected wastewater and also, it reduced COD down to 60 mg/L, a level significantly below the residual COD threshold for biological treatment. This approach, although case‐specific for this study, provided a scientific and general perspective for similar work.

USE OF COAGULANT FROM PLANT ORIGIN AS AN ALTERNATIVE IN THE TREATMENT OF EFFLUENTS FROM SANITATION INDUSTRY

The use of aluminum sulphate-based coagulants, associated with flocculants, is frequent in the treatment of effluents. However, as a by-product, chemical sludge is produced, containing aluminum salts, which pollute the environment. The present work aimed to evaluate the performance of a vegetable coagulant based on tannin in the treatment of effluent from a sanitizing industry. Three experiments were carried out, using 1.0 % w/v of aluminum sulfate and vegetable coagulant, and using 0.25 % w/v of the vegetable coagulant. According to the tests, the vegetable coagulant at 0.25 % m/v reduced 60.4 % of turbidity, 71.0 % of total phosphorus, 98.0 % of anionic surfactants and completely removed animal and vegetable oils and greases and total suspended solids, generating an aluminum-free sludge. The vegetable coagulant acted simultaneously as a coagulant and flocculant and did not require adjustment of effluent pH, not requiring the use of flocculants and alkaline agents, in addition to being effective at lower dosages in relation to the coagulant based on aluminum sulfate. Therefore, the use of vegetable coagulant is technically feasible due to its biodegradability, sludge application potential, and because it does not require special investments or major changes to the existing effluent treatment infrastructure.

A holistic approach to the recovery of valuable substances from the treatment sludge formed from chemical precipitation of fruit processing industry wastewater

In this study, recovery of phenolic substances with Soxhlet extraction, (SE) ultrasound-assisted extraction (UAS), and supercritical CO2 (SC-CO2) extraction methods from chemical sludge obtained with chemical precipitation (FeCl3/PACS, Ca(OH)2/PACS, perlite/PACS, FeCl3/cationic polyelectrolyte) of lemon processing wastewater was investigated. The effect of used coagulants/flocculants and pH on COD and total phenolic substance content (TPC) removal was researched. Recovered phenolic substance profiles were also determined with HPLC-DAD. Additionally, response surface methodology was used to determine optimum treatment conditions. ANOVA analysis showed that pH is a more important variable than coagulant/flocculant doses for all chemical precipitation experimental sets. The highest removal efficiencies for COD and TPC was obtained in FeCl3/PACS (COD: 72.0 %, TPC: 93.7 %). Optimum dose values were determined as pH: 4, FeCl3: 3000 mg/L, PACS: 400 mg/L for FeCl3/PACS, pH: 6.5, Ca(OH)2: 1500 mg/L, PACS: 300 mg/L for Ca(OH)2/PACS, pH: 5.5, PACS: 7000 mg/L, perlite: 50 g/L for perlite/PACS, pH: 4.5, FeCl3: 500 mg/L, polyelectrolyte: 4 mg/L for FeCl3/polyelectrolyte. TPC removal efficiencies were determined as 55 %, 35 %, 57 % and 58 % in these conditions, respectively. Maximum TPC in extracts was determined as 39.03 mg GAE/g extract, 8.81 mg GAE/g extract, and 4.34 mg GAE/g extract for SE, UAS, and SC-CO2, respectively. TPC recovery efficiencies (RTPC) for all chemical sludge were SE > UAS > SC-CO2. Additionally, the TPC profile has shown a difference depending on the extraction method.According to the results of this study, it was concluded that the coagulation-flocculation process may be a suitable alternative for fruit juice processing industry wastewater in terms of both reducing environmental pollution and recovering polyphenolics from formed sludge. Consequently, this study presented a different perspective on the recovery from wastes with valuable substance recovery from chemical sludge.

Quantifying the removal of polybrominated diphenyl ethers (PBDEs) in physical, chemical, and biological sludge treatment systems

Polybrominated diphenyl ethers (PBDE) are priority contaminants historically used as flame retardants. PBDEs are known to occur in wastewater biosolids posing potential concerns with the beneficial land application of the biosolids. This study evaluated the removal of 21 congeners in nine full-scale sludge treatment systems including pelletization (P), alkaline stabilization (AS), and aerobic (AE) and anaerobic (AN) digestion. It is the first study to conduct a mass balance analysis of a broad spectrum of PBDEs during physical, chemical, and biological sludge treatment. The PBDE congener pattern in raw sludge and biosolids samples was consistent with commercial formulations. The fully brominated congener BDE-209 dominated biosolids from all sites with an average concentration of 620 ng/g dry weight (dw), followed by BDE-99 (173 ng/g dw) and BDE-47 (162 ng/g dw). Mass balance analysis on the P and AS processes showed no change in PBDE mass flows with treatment. However, aerobic and anaerobic digestion processes reported significant levels of removal and formation of individual congeners, though the results were not consistent between facilities. One aerobic digestion process (AE2) reported an overall average removal of 48%, whereas the other (AE1) reported very high levels of accumulation of tri- and tetraBDE congeners. Similarly, there were significant variations in PBDE behavior across the five anaerobic digestion plants studied. The plant with the longest solids retention time (SRT) (AN1) reported a moderate removal (50%) of overall PBDE loading and lower congeners, whereas other plants (AN2-AN5) showed significant low (−19%) to high (−166%) levels of formation of lower congeners. The results suggest that reduced SRTs result in formation of lower congeners while extended SRTs can lead to moderate removal of some PBDEs. Conventional sludge treatment result in low to moderate PBDE removal and advanced thermal conversion technologies may be needed to improve the contaminant removal during sludge treatment.

Recycling Fe and improving organic pollutant removal via in situ forming magnetic core-shell Fe3O4@CaFe-LDH in Fe(II)-catalyzed oxidative wastewater treatment

Due to its high efficiency, Fe(II)-based catalytic oxidation has been one of the most popular types of technology for treating growing organic pollutants. A lot of chemical Fe sludge along with various refractory pollutants was concomitantly produced, which may cause secondary environmental problems without proper disposal. We here innovatively proposed an effective method of achieving zero Fe sludge, reusing Fe resources (Fe recovery = 100%) and advancing organics removal (final TOC removal > 70%) simultaneously, based on the in situ formation of magnetic Ca-Fe layered double hydroxide (Fe3O4@CaFe-LDH) nano-material. Cations (Ca2+ and Fe3+) concentration (≥ 30 mmol/L) and their molar ratio (Ca:Fe ≥ 1.75) were crucial to the success of the method. Extrinsic nano Fe3O4 was designed to be involved in the Fe(II)-catalytic wastewater treatment process, and was modified by oxidation intermediates/products (especially those with COO− structure), which promoted the co-precipitation of Ca2+ (originated from Ca(OH)2 added after oxidation process) and by-produced Fe3+ cations on its surface to in situ generate core-shell Fe3O4@CaFe-LDH. The oxidation products were further removed during Fe3O4@CaFe-LDH material formation via intercalation and adsorption. This method was applicable to many kinds of organic wastewater, such as bisphenol A, methyl orange, humics, and biogas slurry. The prepared magnetic and hierarchical CaFe-LDH nanocomposite material showed comparable application performance to the recently reported CaFe-LDHs. This work provides a new strategy for efficiently enhancing the efficiency and economy of Fe(II)-catalyzed oxidative wastewater treatment by producing high value-added LDHs materials.

Penggunaan Jar Test untuk Penentuan Dosis dan Komposisi Optimum Komposit Koagulan Poly Aluminium Chloride (PAC) – Kitosan dalam Menurunkan TSS dan COD

Laundry waste is a pollutant that has pollutant parameters such as TSS and COD. One alternative processing is flocculation-coagulation using synthetic coagulants. The advantage of synthetic coagulants is that they are able to remove high concentrations of pollutants, but the disadvantages are that they produce quite a lot of chemical sludge and the pH of the water becomes acidic because the higher the concentration, the more coagulant is used. Previous research explains that chitosan at low doses has good penyisihan efficiency so that when combined with PAC it is hoped that it can increase penyisihan efficiency with less sludge. The purpose of this study was to determine the optimum dosage and composition for PAC and chitosan coagulant composites using the Jar Test. The Jar Test method for determining the optimum dose uses fast stirring at 140 rpm for 2 minutes and then slow stirring at 60 rpm for 15 minutes and settling for 30 minutes. Determination of the optimum dose by adding a coagulant composite of 300 ppm, 500 ppm, and 700 ppm and by varying the composition at each dose, namely 1:1, 1:3, and 3:1 between PAC-chitosan. The best conditions from the study obtained an optimum dose of 700 ppm and an optimum composition of 3:1 between PAC and chitosan resulting in COD and TSS penyisihan efficiencies of 70.04% and 90.82%.