Study on optimization and performance of biological enhanced activated sludge process for pharmaceutical wastewater treatment

Concentrating emulsified oily wastewater by integrated membrane technology

The effects of operating pressure, feed temperature, oil content of feed solution, and membrane surface flow rate on membrane flux, concentration multiple, and average particle size of oil droplets in the concentrated solution during the single-stage membrane concentration process were investigated. The experimental results show that within a certain operating range, the membrane flux increases with the increase of operating pressure, feed temperature, and membrane surface flow rate, while it decreases continuously with the increase of feed oil content. Optimal conditions for single stage concentration based on membrane flux, concentration factor, and average particle size of oil droplets in the concentrated solution were determined. Then, on the basis of single-stage membrane concentration conditions, three different pore size separation membranes are combined in different ways. After concentration through multi-stage membranes, the particle size of the oil droplets in the concentrate is greater than 20 μm, which is beyond the particle size range of the emulsified oil, and the concentration of the oil in the concentrate is 20-30 times that of the original oil. The method can realize the recovery of oil resources in the emulsified oil-containing wastewater.

Organic carbon release, denitrification performance and microbial community of solid-phase denitrification reactors using the blends of agricultural wastes and artificial polymers for the treatment of mariculture wastewater

This paper explored the possibility of heterotrophic denitrification driven by composite solid carbon sources in low carbon/nitrogen ratio marine recirculating aquaculture wastewater. In this study, two agricultural wastes, reed straw (RS), corn cob (CC) and two artificial polymers, polycaprolactone (PCL), poly3-hydroxybutyrate-hydroxypropionate (PHBV) were mixed in a 1:1 ratio to compare the carbon release characteristics of the four composite carbon sources (RS+PCL, RS+PHBV, CC+PCL, and CC+PHBV) and their effects on improving the mariculture wastewater for denitrification. Dissolved organic carbon (DOC) after carbon source release (4.96-1.07 mg/g), total organic carbon/chemical oxygen demand (1.9-0.79) and short-chain fatty acids (SCFAs) (4.23-0.21 mg/g) showed that all the four composite solid carbon sources had excellent organic carbon release ability, and the CC+PCL group had the highest release of DOC and SCFAs. Energy-dispersive X-ray spectroscopy, scanning electron microscopy, and Fourier-transform infrared spectroscopy were used to observe the changes in the surface characteristics of the composite carbon source before and after application. And results showed that the stable internal structure enabled CC+PCL group to have continuous carbon release performance and achieved the maximum denitrification efficiency (93.32 %). The NRE results were supported by the abundance of the Proteobacteria microbial community at the phylum level and Marinobacter at the genus level. Quantitative real-time PCR (q-PCR) indicated CC-containing composite carbon source groups have good nitrate reduction ability, while PCL-containing composite carbon source groups have better nitrite reduction level. In conclusion, the carbon source for agricultural wastes and artificial polymers can be used as an economic and effective solid carbon source for denitrification and treatment of marine recirculating aquaculture wastewater.

Study on the removal characteristics and degradation pathways of highly toxic and refractory organic pollutants in real pharmaceutical factory wastewater treated by a pilot-scale integrated process

Introduction

Pharmaceutical wastewater frequently contains high levels of toxic pollutants. If they are discharged untreated, they pose a threat to the environment. The traditional activated sludge process and the advanced oxidation process do not sufficiently remove toxic and conventional pollutants from pharmaceutical wastewater treatment plants (PWWTPs).

Methods

We designed a pilot-scale reaction system to reduce toxic organic pollutants and conventional pollutants from pharmaceutical wastewater during the biochemical reaction stage. This system included a continuous stirred tank reactor (CSTR), microbial electrolysis cells (MECs), an expanded sludge bed reactor (EGSB), and a moving bed biofilm reactor (MBBR). We used this system to further investigate the benzothiazole degradation pathway.

Results and discussion

The system effectively degraded the toxic pollutants (benzothiazole, pyridine, indole, and quinoline) and the conventional chemicals (COD, NH4+-N, TN). During the stable operation of the pilot-scale plant, the total removal rates of benzothiazole, indole, pyridine, and quinoline were 97.66, 94.13, 79.69, and 81.34%, respectively. The CSTR and MECs contributed the most to the removal of toxic pollutants, while the EGSB and MBBR contributed less to the removal of the four toxic pollutants. Benzothiazoles can be degraded via two pathways: the benzene ring-opening reaction and the heterocyclic ring-opening reaction. The heterocyclic ring-opening reaction was more important in degrading the benzothiazoles in this study.

Conclusion

This study provides feasible design alternatives for PWWTPs to remove both toxic and conventional pollutants at the same time.

Residual β-lactam antibiotics and ecotoxicity to Vibrio fischeri, Daphnia magna of pharmaceutical wastewater in the treatment process

The discharge of pharmaceutical wastewater introduces numerous pollutants into the environment, and their pollution level reduction has aroused extensive concern. This study investigated the variation in residual antibiotics and ecotoxicity to two nutritional-level model organisms in the pharmaceutical wastewater treatment process (PWTP). The wastewater in the equalization tank contained massive organic matters (2.9-18.7 times higher than the permissible values in GB21903-2008) and antibiotics (310.88 μg/L), posing extremely toxic effects to Vibrio fischeri (V. fischeri) and Daphnia magna (D. magna). The biological anaerobic/aerobic treatment units contributed the most to the reduction of antibiotics and the ecotoxicity to both organisms, with the removal rates of 72% and > 90%, respectively. The ecotoxicity of pharmaceutical wastewater was strongly and positively correlated with the residual antibiotics, amoxicillin, cephalexin, ammonia nitrogen, and total phosphorus (P < 0.05). However, the detected amounts of amoxicillin and cephalexin were approximately 10⁵ times lower than the predicted no-effect concentrations of amoxicillin and cephalexin to V. fischeri and D. magna in freshwater, which implied the joint ecotoxicity posed by multicomponent mixtures, such as the residual antibiotics and organic toxic substances, rather than the specific residual antibiotics. This study provides a better understanding of the variations and residual levels of pollutants in PWTPs, including their ecotoxicity risk to the aquatic environment, highlighting the need to optimize pharmaceutical wastewater treatment technologies.

Antibiotic residue and toxicity assessment of wastewater during the pharmaceutical production processes

Various pollutants are released during pharmaceutical production processes, which is of great concern. Most studies have focused on the terminal treatment results of mixed pharmaceutical wastewater, and further research on wastewater from the production processes is required. This study investigated the wastewater quality indicators, residual antibiotics, and biological toxicity of the wastewater during the production process in a large pharmaceutical producing factory in Northern China. The wastewater contained numerous organic pollutants, with the chemical oxygen demand (COD) values ranging from 2.0 × 10³ to 2.6 × 10⁵ mg L^-1 and the total nitrogen (TN) values ranging from 1.3 × 10³ to 2.0 × 10⁴ mg L^-1. High concentrations of cephalexin and cefradine remained in the wastewater of the production workshop, with the highest concentration of cefradine reaching 1328 mg L^-1. The wastewater from the oxidation and solvent recovery workshops was more toxic to Vibrio fischeri and Daphnia magna than that of other workshops. Moreover, the biological acute toxicity of wastewater was significantly correlated with the concentration of COD and TN (p < 0.01). This study provides new insights into the treatment of antibiotic production wastewater, illuminating the incomplete extraction of products and the significant risk posed by pharmaceutical wastewater to the environment.

Feasibility of partial-denitrification/ anammox for pharmaceutical wastewater treatment in a hybrid biofilm reactor

Biological nitrogen removal from pharmaceutical wastewater has drawn increasing attention due to biotoxicity and inhibition. In this study, for the first time, a novel approach integrating partial-denitrification with anaerobic ammonia oxidation (PD/A) in a sequencing biofilm batch reactor (SBBR) was proposed and demonstrated to be efficient to treat the bismuth nitrate and bismuth potassium citrate manufacturing wastewater, containing ammonia (NH₄⁺-N) and nitrate (NO₃^--N) of 6300±50 mg L ^- 1 and 15,300±50 mg L ^- 1. The maximum anammox activity was found at the shock effect of influent total nitrogen (TN) of 100 mg L ^- 1 with NO₃^--N/NH₄⁺-N of 1.0. Long-term operation demonstrated that the PD/A biofilm was developed rapidly after 30 days using synthetic influent, with TN removal efficiency increasing from 40.9% to 80.8%. Significantly, the key bacteria for PD/A had high tolerance and adapted rapidly to pharmaceutical wastewater, achieving a relatively stable TN removal efficiency of 81.2% with influent NH₄⁺-N and NO₃^--N was 77.9 ± 2.6 and 104.1 ± 4.4 mg L ^- 1 at a relatively low COD/NO₃^--N of 2.6. Anammox pathway contributed to TN removal reached 83.6%. Significant increase of loosely-bound extracellular polymeric substances was obtained with increasing protein of 3-turn helices structure as response to the inhibitory condition. High-throughput sequencing analysis revealed that the functional genus Thauera was highly enriched in both biofilms (9.5%→43.6%) and suspended biomass (15.5%→57.5%), which played a key role in high NO₂^--N accumulation. While the anammox bacteria decreasing from 7.8% to 1.6% in biofilm, and from 1.8% decreased to 0.1% in the suspended sludge. Overall, this study provides a new method of high-strength pharmaceutical wastewater treatment with low energy consumption and operation cost, as well as a satisfactory efficiency.

Comparative investigation of acetaminophen degradation in aqueous solution by UV/Chlorine and UV/H2O2 processes: Kinetics and toxicity assessment, process feasibility and products identification

The degradation of acetaminophen (ACM) was comparatively studied by UV/chlorine and UV/H₂O₂ systems. An apparent reduction in the removal rate was observed above the optimum pH levels of 7.0 and 3.0 in UV/chlorine and UV/H₂O₂ processes, respectively. The relative contribution of each oxidizing agent in ACM removal using the two advanced oxidation processes (AOPs) was evaluated. Even though hydroxyl radicals, with the contribution percentage of 90.1%, were determined as the primary oxidizing species in ACM removal using the UV/H₂O₂ process, reactive chlorine species (RCS), with 43.8% of contribution percentage, were also found to play a pivotal role in ACM removal using the UV/chlorine process. For instance, dichlorine radical (Cl₂^•-) showed an acceptable contribution percentage of 32.2% in the degradation of ACM by the UV/chlorine process. The rate of ACM degradation significantly rose to 99.9% and 75.6%, as higher amounts of oxidants were used in the UV/chlorine and UV/H₂O₂ processes, respectively, within 25 min. The introduction of HCO₃^- ions and humic acid remarkably decreased the rate of ACM degradation in both techniques used in this study. The presence of NO₃^- and Cl^- ions did not considerably affect the removal rate in the UV/chlorine process. The acute toxicity analysis revealed that a more pronounced reduction in the ACM solution toxicity could be achieved by the UV/H₂O₂ process compared to the UV/chlorine process, which should be ascribed to the formation of chlorinated products in the UV/chlorine treatment. Eventually, plausible oxidation pathways were proposed for each process.