Enhanced treatment of swine wastewater by electron beam irradiation and ion-exchange biological reactor

Porous Hierarchical Ni/Mg/Al Layered Double Hydroxide for Adsorption of Methyl Orange from Aqueous Solution

A basic urea technique was successfully used to synthesize Mg/Al-Layered double hydroxides (Mg/Al LDHs), which were then calcined at 400 °C to form Mg/Al-Layered double oxides (Mg/Al LDOs). To reconstruct LDHs, Mg/Al LDOs were fabricated with different feeding ratios of Ni by the co-precipitation method. After synthesis, the Ni/Mg/Al-layered double hydroxides (NMA-LDHs) with 20% and 30% Ni (S1 and S2) were roasted at 400 °C and transformed into corresponding Ni/Mg/Al-layered double oxides (NMA-LDOs) (S1a and S2b, respectively). The physiochemical properties of synthesized samples were also evaluated by various characterization techniques, such as X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FTIR), and Brunauer, Emmett, and Teller (BET). The adsorption behavior of methyl orange (MO) onto the synthesized samples was evaluated in batch adsorption mode under varying conditions of contact time, adsorbent quantity, and solution pH. As the dosage amount increased from 0.01-0.04 g, the removal percentage of MO dye also increased from 83% to 90% for S1, 84% to 92% for S1a, 77% to 87% for S2, and 93% to 98% for S2b, respectively. For all of the samples, the adsorption kinetics were well described by the pseudo-second-order kinetic model. The equilibrium adsorption data were well fitted to both Langmuir and Freundlich models for methyl orange (MO). Finally, three adsorption-desorption cycles show that NMA-LDHs and NMA-LDOs have greater adsorption and reusability performance for MO dye, signifying that the design and fabrication strategy can facilitate the application of the natural hydrotalcite material in water remediation.

The characteristics of stepwise ultrasonic hydrolysates of sludge for enhancing denitrification

The disposal of waste activated sludge (WAS) accounts for approximately 60 % of wastewater treatment plant operating costs. In this study, according to the reaction time and water quality parameters, ultrasonic hydrolysis of WAS is divided into three stages, including floc-disintegration (0-25.2 kJ/g TS), cell-disruption (25.2-36 kJ/g TS), and cell-degradation (over 36 kJ/g TS). The results show that more than 70 % carbon distributes inside the cell, which also contains 63.8 % protein enhancing denitrification capacity. Moreover, cell-degradation hydrolysate has a higher proportion of readily biodegradable COD, indicating that intracellular organic matter is more capable of denitrification than extracellular. Therefore, the optimal ultrasonic operating range is E_s = 36-72 kJ/g TS as carbon source, and obtain the hydrolysate with high ratio of soluble chemical oxygen demand to total nitrogen for denitrification. Furthermore, this study supports the comprehensive interpretation of ultrasonic hydrolyzed WAS and the characteristics of hydrolysate as carbon source for enhancing denitrification.

Effect of microaerophilic treatment on swine wastewater (SWW) treatment: Engineering and microbiological aspects

The microaerobic process on swine wastewater (SWW) treatment was investigated, evaluating its effect on organic matter hydrolysis and removal, biogas production, operational stability, and microbial community structure. UASB reactors operating under higher organic loading rates (OLRs) and lower hydraulic retention times (HRTs) than those found in the SWW treatment literature were also assessed. The microaerophilic reactor R2 presented a higher total and particulate organic matter removals and operational stability than the anaerobic reactor R1, reaching COD_P removals of 79.4 ± 4.6%. In the specific methanogenic activity (SMA) tests, the microaerobic sludge (R2) showed hydrolytic and acetogenic/methanogenic activity superior to inoculum and anaerobic sludge (R1). The microbiological evaluation of R2 revealed the high presence of hydrolytic microorganisms, therefore justifying the higher hydrolytic activity found in the SMA tests and higher particulate organic matter removal found in the microaerobic reactor.

Impact of hydraulic retention time on swine wastewater treatment by aerobic granular sludge sequencing batch reactor

In this study, the effect of hydraulic retention time (HRT) on the performance of aerobic granular sludge (AGS) treating swine wastewater (SW) in sequencing batch reactor (SBR) was investigated. The HRT was set at 4.8, 6, 8, 12, and 16 h and performed in five parallel aerobic granular sludge sequence batch reactors (AGSBRs), respectively. The results showed that sedimentation performance and biomass concentration were improved by decreasing the HRT from 16 to 8 h. However, when further decreasing HRT from 8 to 4.8 h, the AGS performance became worse. The AGS process with HRT of 8 h exhibited high pollutant removal efficiency, and an abundant microbial community and a stable microbial community structure were observed. High-throughput 16S rRNA analysis revealed that there were significant differences between the microorganisms in AGS samples with HRT of 8 h at the phylum level and that the dominant microbes changed as the process proceeded. At the genus level, the species and relative abundance of microorganisms gradually evolved for AGS stability in all cases.

Application of electron beam water radiolysis for sewage sludge treatment-a review

A review of the applicability of electron beam water radiolysis for sewage sludge treatment is presented. Electron beam treatment has been proven to be a successful approach to the disinfection of both wastewater and sewage sludge. Nevertheless, before 2000, there were concerns about the perceived high capital costs of the accelerator and with public acceptance of the usage of radiation for water treatment purposes. Nowadays, with increased knowledge and technological development, it may be not only possible but also desirable to use electron beam technology for risk-free sewage sludge treatment, disposal and bio-friendly fertiliser production. Despite the developing interest in this method, there has been no attempt to perform a review of the pertinent literature relating to this technology. It appears that understanding of the mechanism and primary parameters of disinfection is key to optimising the process. This paper aims to reliably characterise the sewage sludge electron beam treatment process to elucidate its major issues and make recommendations for further development and research. Graphical abstract.

Elucidating salinity adaptation and shock loading on denitrification performance: Focusing on microbial community shift and carbon source evaluation

To understand the denitrification efficiency and microbial community shift with increasing salinity in salinity adaptation and shock loading process, nitrate (NO3--N), nitrite (NO2--N) and chemical oxygen demand (COD) removal efficiencies were monitored feeding acetate and primary sludge fermentation liquid. During adaptation process, salinity had little effect on NO3--N removal efficiency (>99.0%) with acetate-fed, while for fermentation liquid-fed, it decreased to around 97% at high salinity (>2.5%). Effluent NO2--N was lower than 0.1 mg/L, though obvious fluctuation of NO2--N was observed with fermentation liquid-fed when salinity change. During shock loading process, denitrification process all had slight decrease when the salinity abruptly increased to 5.0%. Traditional denitrifier of Thauera was the dominant genus, and a specialized microbial community of Azoarcus in salinity adaptation and Paracoccus in shock loading for denitrification showed high salinity tolerant. Meanwhile, microbial diversity was enriched with fermentation liquid-fed at high salinity condition.

Simultaneous Removal of Pollutants and Recovery of Nutrients from High-Strength Swine Wastewater Using a Novel Integrated Treatment Process

Simple Summary

Due to the increasing trend of swine consumption in recent decades, swine husbandry practices have become more intensive in Korea. Intensive swine farming practices inevitably result in an increment of wastewater production. Treatment of high strength swine wastewater (SWW) is therefore becoming a matter of concern in Korea. Moreover, with the increasing number of swine heads, swine farms are having issues with malodor, sanitation, and disease control. In this study, a novel integrated treatment process was tested for the simultaneous removal of pollutants and nutrient recovery from high strength swine wastewater. The integrated treatment process used in this study successfully removed the nutrients and other pollutants through biological treatment, recovered the nutrients using struvite crystallization process and decolorized as well as disinfected the effluent before discharge into water bodies by electrochemical treatment. Therefore, using the proposed integrated treatment process, it might be possible to ensure efficient SWW management along with societal and environmental sustainability.

Abstract

In this study, a novel treatment approach combining biological treatment, struvite crystallization, and electrochemical treatment was developed and its efficiency for the simultaneous removal of pollutants and recovery of nutrients from high strength swine wastewater (SWW) was verified. For all the parameters, maximum removal efficiencies in the lab-scale test were obtained in the range of 93.0–98.7% except for total solids (TS) (79.4%). Farm-scale process showed overall removal efficiencies for total nitrogen (TN), total phosphorus (TP), soluble total organic carbon (sTOC), and color as 94.5%, 67.0%, 96.1%, and 98.9%, respectively, while TS, suspended solids (SS), ammonium nitrogen (NH₄-N), and ortho-phosphate (O-P) concentrations were reduced by 91.5%, 99.6%, 98.6%, and 91.9%, respectively. Moreover, the struvite recovered from SWW showed heavy metal concentrations within the range of the Korean standard for fertilizers and feedstocks and thus, suggesting its potential application as fertilizer and in animal feed production. Using the proposed process, the SWW was converted to liquid compost as a quick-acting fertilizer, struvite as a slow-release fertilizer, and the decolorized and disinfected effluent after electrochemical treatment was safe for discharge according to Korean standard. Therefore, the novel integrated treatment process used in this study can be considered as a solution for SWW management and for the simultaneous removal and recycling of nutrients (N and P).

Optimizing real swine wastewater treatment with maximum carbohydrate production by a newly isolated indigenous microalga Parachlorella kessleri QWY28

In this study, a newly discovered microalga Parachlorella kessleri QWY28 with a superior ability to treat real swine wastewater, was isolated and explored. The optimal culture conditions of 30 °C and 600 μmol/m²·s were set to improve the practical application potential, achieving maximum pollutant removal efficiencies of 88% COD, 95% TN and almost 100% TP, with carbohydrate production at 646 mg/L·d. These results present the highest efficiencies reported to date, for non-sterilized real swine wastewater without pretreatment. These findings support the practical feasibility of combined microalgal swine wastewater purification and energy production systems.

Combination of nejayote and swine wastewater as a medium for Arthrospira maxima and Chlorella vulgaris production and wastewater treatment

Nejayote and swine wastewater are highly pollutant effluents and a source of organic matter load that sometimes released into water bodies (rivers or lakes), soils or public sewer system, with or without partial treatments. Nejayote is a wastewater product of alkaline cooking of maize, whereas, swine wastewater results from the primary production of pigs for the meat market. Owing to the presence of environmentally related pollutants, both sources are considered the major cause of pollution and thus require urgent action. Herein, we report a synergistic approach to effectively use and/or treat Nejayote and swine wastewater as a cost-effective culture medium for microalgae growth, which ultimately induces the removal of polluting agents. In this study, the strains Arthrospira maxima and Chlorella vulgaris were grown using different dilutions of Nejayote and swine wastewater. Both wastewaters were used as the only source of macronutrients and trace elements for growth. For A. maxima, the treatment of 10% nejayote and 90% of water (T3) resulted in a cell growth of 32 × 10⁴ cell/mL at 12 days (μ_max = 0.27/d). While, a mixture of 25% swine wastewater, 25% nejayote and 50% water (T2) produced 32 × 10⁴ cell/mL at 18 days (μ_max = 0.16/d). A significant reduction was also noted as 92% from 138 mg/L of TN, 75% from 77 mg/L of TP, and 96% from 8903 mg/L of COD, among different treatments. For C. vulgaris, the treatment of 10% swine wastewater and 90% water (T1) gave a cell growth of 128 × 10⁶ cell/mL (μ_max = 0.57/d) followed by T3 yielded 62 × 10⁶ cell/mL (μ_max = 0.70/d) and T2 yielded 48 × 10⁶ cell/mL (μ_max = 0.54/d). Up to 91% reduction from 138 mg/L of TN, 85% from 19 mg/L of TP and 96% from 4870 mg/L of COD was also recorded. These results show that microalgae can be used to treat these types of wastewater while at the same time using them as a culture media for microalgae. The resultant biomass can additionally be used for getting other sub-products of commercial interest.

Advanced treatment of gamma irradiation induced livestock manure using bioelectrochemical ion-exchange reactor

Organic matter and nitrogen in livestock manure was pre-treated by gamma irradiation. The optimal dose ranged 30-50 kGy for solubilization of organic matter and nitrogen. Carbohydrates and proteins increased with the applied dose. Lipids did not show a regular increase pattern. A large amount of organic nitrogen in livestock manure was solubilized after gamma irradiation. The pre-treated livestock manure was treated using a bioelectrochemical ion-exchange reactor. High removal of organic matter and nitrogen was achieved with the applied dose of 50 kGy. The maximum 88.5% of chemical oxygen demand removal was obtained in the bioelectrochemical ion-exchange reactor due to readily biodegradable chemical oxygen demand fraction. Nitrogen removal was significantly affected by ammonia flux of ion-exchange membrane between anaerobic and aerobic chamber. With a high ammonia flux of 4.7513 mg/m²/sec, the maximum ammonia removal was 79.1%.

Enhancing denitrification with waste sludge carbon source: the substrate metabolism process and mechanisms

Using waste sludge internal carbon source for nitrogen removal in wastewater has drawn much attention, due to its economic advantages and sludge reduction. In this study, the performance of enhanced denitrification with waste sludge thermal hydrolysate and fermentation liquid as carbon sources at different SCOD/N (soluble chemical oxygen demand/NO₃^--N) was investigated. The optimum SCOD/N was 8 for sludge thermal hydrolysate and 7 for fermentation liquid, with NO₃^--N removal efficiency of 92.3 and 98.9%, respectively, and no NO₂^--N accumulation. To further understand the fate of sludge carbon source during denitrification, the changes of SCOD, proteins, carbohydrates, and volatile fatty acids (VFAs) were analyzed, and three-dimensional fluorescence excitation-emission matrix (EEM) spectroscopy with fluorescence regional integration (FRI) analysis was introduced. The utilization of SCOD was consistent with NO₃^--N reduction, and the utilization efficiency of different organic matter was as follows: VFAs > proteins > carbohydrates. The soluble organic-like materials (region IV) were the most readily utilized organic matter according to three-dimensional fluorescence EEM spectroscopy. Regarding denitrification mechanisms, the denitrification rate (V_DN), denitrification potential (P_DN), heterotroph anoxic yield (Y_H), and the most readily biodegradable COD (S_S) were also investigated.

Effects of hydraulic retention time (HRT) on denitrification using waste activated sludge thermal hydrolysis liquid and acidogenic liquid as carbon sources

Waste activated sludge (WAS) internal carbon source can efficiently and economically enhance denitrification, and hydraulic retention time (HRT) is one of the most important operational parameters for denitrification. The effects of HRT on denitrification were investigated with WAS thermal hydrolysis liquid and acidogenic liquid as carbon sources in this study. The optimal HRT was 12h for thermal hydrolysis liquid and 8h for acidogenic liquid, with NO₃^--N removal efficiency of 91.0% and 97.6%, respectively. In order to investigate the utilization of sludge carbon source by denitrifier, the changes of SCOD (Soluble chemical oxygen demand), proteins, carbohydrates, and VFAs (Volatile fatty acids) during denitrification process were analyzed and three-dimensional fluorescence excitation-emission matrix (EEM) spectroscopy with fluorescence regional integration (FRI) analysis was introduced. The kinetics parameters of denitrification rate (V_DN), denitrification potential (P_DN) and heterotroph anoxic yield (Y_H) were also investigated using sludge carbon source at different HRT.

Nutrient removal and lipid production by Coelastrella sp. in anaerobically and aerobically treated swine wastewater

Coelastrella sp. QY01, a microalgae species isolated from a local pond, was identified and used for the treatment of anaerobically and aerobically treated swine wastewater (AnATSW). Microalgal growth characteristics, nutrient removal and lipid accumulation of QY01 cultivated in the initial concentration of AnATSW ranged from 63 to 319mg NH3-N/L were examined. The specific growth rate of QY01 cultivated in cultures ranged from 0.269 to 0.325day(-1) with a biomass productivity from 42.77 to 57.46mgL(-1)day(-1). Removal rates for NH3-N, TP and inorganic carbon in AnATSW at the various nutrient concentrations ranged from 90% to 100%, from 90% to 100% and from 74% to 78%, respectively. The lipid content of QY01 ranged from 22.4% to 24.8%. The lipid productivity was positive correlation with the biomass productivity. 40% AnATSW was optimal for QY01 cultivation, in which nutrient removal and productivity of biomass and lipid were maximized.