Disruption of cell to cell communication in the aeration unit of a cannibal process: Sludge reduction efficiency and related mechanisms

Zhou

et al. 2021

Environ. Sci. Technol.

Packing carriers into the anaerobic side-stream reactor (ASSR) can enhance sludge reduction and save footprint by investigating ASSR-coupled membrane bioreactors (AP-MBRs) under different hydraulic residence times of the ASSR (HRT SR ). Three AP-MBRs and an anoxic-aerobic MBR (AO-MBR) showed efficient chemical oxygen demand (>94.2%) and ammonium nitrogen removal (>99.3%). AP-MBRs have higher (p < 0.05) total nitrogen (61.4−67.7%) and total phosphorus (57.5−63.8%) removal than AO-MBRs (47.8 and 47.7%). AP-MBRs achieved sludge reduction efficiencies of 11.8, 31.8, and 36.2% at HRT SR values of 2.5, 5.0, and 6.7 h. Packing carriers greatly improved sludge reduction under low HRT SR and is promising for accelerating sludge reduction in compact space. Metagenomic sequencing analysis showed that genes responsible for metabolism were enriched in AO-MBRs, while genes related to cellular motility and cell signaling were more abundant in the AP-MBRs. A longevity-regulating pathway showed that long lifespan provided more opportunities for worms to prey bacteria. Microscopic examination revealed that some specific protozoa (Arcella, Clathrulina, Aspidisca, Litonotus, Chiloclonella, and Vorticella) and metazoa (Rotaria and Aeolosoma hemprichi) were enriched in ASSRs. Aeolosoma hemprichi was only detected in ASSRs, and unique Cylops appeared on carriers. These results contribute to growing understanding of micrometabolic mechanisms including functional genes and microfauna-driving sludge reduction.

Section: Resultsmentioning

confidence: 98%

Bacterial and Microfauna Mechanisms for Sludge Reduction in Carrier-Enhanced Anaerobic Side-Stream Reactors Revealed by Metagenomic Sequencing Analysis

Zhou

et al. 2021

Environ. Sci. Technol.

“…The key point of EBPR is exposing PAO bacteria in both aerobic and anaerobic conditions [16,24]. Sludge passage or periodic circulation through SHT contributes to the growth of phosphorus accumulating organisms capable of biologically removing the phosphorus [1,[27][28][29][30]. Velho et al reported that adding ASSR can affect the mechanism of biological phosphorus removal.…”

Section: Effluent Phosphorus Concentration Changesmentioning

confidence: 99%

Studying the Effluent Quality of Enhanced Modified Ludzack Ettinger-oxic Settling Anaerobic Process (E-MLE-OSA) for Treating Real Municipal Wastewater

Nikpour,

Jalilzadeh Yengejeh,

Takdastan

et al. 2121

JAEHR

Background: Wastewater collection, treatment, discharge, additionally as reusing the treated wastewater in urban are critical factors for maintaining public health preventing contamination of water resources. This study aimed to investigate the performance of enhanced modified Ludzack Ettinger process-oxic settling anaerobic (MLE-OSA) process for treating real municipal wastewater in Sari wastewater Treatment, Sari City, Iran. Methods: To combine the OSA process technique with the MLE system, the Sludge Holding Tanks (SHT) were implemented in the return sludge line of designed pilot studies which comprised 1) MLE, which was regarded as the control system similar; 2) MLE-OSA4 with a 70-L SHT operated at 4-h Hydraulic Retention Time (HRT), and 3) MLEOSA6 with a 107-L SHT operated at 6-h HRT. To start the process, the overflow effluent of the primary settling tank of the Sari wastewater treatment plant was used. After 45-60 days, the reactors reached a steady state. The parameters of Dissolved Oxygen (DO), Oxidation-Reduction Potential (ORP), temperature, pH, Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD5), Total Suspended Solids (TSS), and nutrients were analyzed. Results: The results revealed that the average TSS, COD, BOD, phosphorus, nitrite, nitrate, and total nitrogen in MLEOSA4 effluent decreased 20.1, 14.6, 2.97, 10, 51.1, 19.3, and 20.7%, respectively compared to MLE. Similarly, in MLE-OSA6, the values decreased 34.2, 16.1, 14.6, 16.7, 69.6, 31.3, and 25.8%, respectively compared to the control process. Conclusion: Therefore, using natural wastewater, the enhanced MLE-OSA process showed better performance in removing the study parameters and better quality for the effluent. Furthermore, the quality of effluent is following the Iran Department of Environment (IDE).

“…In fact, the treatment and disposal of this excess sludge can represent between 25-65% of the total operating cost of a WWTP. Thus, most of the conventional physicochemical and biological methods turn an IWW problem into a solid waste disposal problem (Sara Pérez-Elvira et al, 2017; Salehiziri et al, 2018). This is why the management of these solid wastes must be carried out from a sustainable approach in which some requirements are met in the e cient recycling of resources without having an environmental impact (Fytili & Zabaniotou, 2008).…”

Section: Sludge Treatment Unitmentioning

confidence: 99%

Industrial Wastewater Treatment Technologies For Reuse, Recycle, And Recovery: Advantages, Disadvantages, And Gaps.

Mejía¹,

Maturana²,

Gómez³

et al. 2021

Preprint

To reduce demand and discharge, instead of industrial wastewater being poorly treated and disposed of, it can be recycled, reused, or recovered if it is properly managed, thus having a substantial decrease in the water requirement and environmental impacts. The challenge is to select the appropriate process or combination of processes to achieve this based on the wastewater quality. Consequently, the objective of this investigation is to review every technology from conventional through advanced, for reliable and sustainable wastewater treatment and derived sludges, focusing on advantages, disadvantages, and technical gaps for development. Even though there is a wide range of possible technologies, it was evinced that there is huge potential to exploit and make them economically and sustainably viable for waste processing and circular economy, even in the mature massively implemented wastewater treatment technologies in the industry. Overall, we identify that independently from the technology to be studied, the future investigations on every unit, especially on those not vastly implemented, should be focused on: (1) The capacity in removing selected pollutants and decreasing impurities, (2) energy efficiency, (3) environmental safety, (4) economic viability, (5) hybrid processes, and (6) sustainability by waste processing.