scholarly journals Particle balance and return loops for microplastics in a tertiary-level wastewater treatment plant

Author(s):  
Pauliina Salmi ◽  
Kalle Ryymin ◽  
Anna K. Karjalainen ◽  
Anna Mikola ◽  
Emilia Uurasjärvi ◽  
...  

Abstract Microplastics (MPs) from households, stormwater, and various industries are transported to wastewater treatment plants (WWTPs), where a high proportion of them are captured before discharging their residuals to watersheds. Although recent studies have indicated that the removed MPs are mainly retained in wastewater sludge, sludge treatment processes have gained less attention in MP research than water streams at primary, secondary, and tertiary treatments. In this study, we sampled twelve different process steps in a tertiary-level municipal WWTP in central Finland. Our results showed that, compared to the plant influent load, three times more MPs circulated via reject water from the sludge centrifugation back to the beginning of the treatment process. Especially fibrous MPs were abundant in the dewatered sludge, whereas fragment-like MPs were observed in an aqueous stream. We concluded that, compared to the tertiary effluent, sludge treatment is the major exit route for MPs into the environment, but sludge treatment is also a return loop to the beginning of the process. Our sampling campaign also demonstrated that WWTPs with varying hydraulic conditions (such as the one studied here) benefit from disc filter–based tertiary treatments in MP removal.

2007 ◽  
Vol 56 (7) ◽  
pp. 21-31 ◽  
Author(s):  
D. Brdjanovic ◽  
M. Mithaiwala ◽  
M.S. Moussa ◽  
G. Amy ◽  
M.C.M. van Loosdrecht

This paper presents results of a novel application of coupling the Activated Sludge Model No. 3 (ASM3) and the Anaerobic Digestion Model No.1 (ADM1) to assess a tropical wastewater treatment plant in a developing country (Surat, India). In general, the coupled model was very capable of predicting current plant operation. The model proved to be a useful tool in investigating various scenarios for optimising treatment performance under present conditions and examination of upgrade options to meet stricter and upcoming effluent discharge criteria regarding N removal. It appears that use of plant-wide modelling of wastewater treatment plants is a promising approach towards addressing often complex interactions within the plant itself. It can also create an enabling environment for the implementations of the novel side processes for treatment of nutrient-rich, side-streams (reject water) from sludge treatment.


2002 ◽  
Vol 46 (10) ◽  
pp. 71-77 ◽  
Author(s):  
K.-H. Ahn ◽  
K.Y. Park ◽  
S.K. Maeng ◽  
J.H. Hwang ◽  
J.W. Lee ◽  
...  

An ozone treatment system was introduced as an alternative method for municipal sludge treatment and disposal. A pilot-scale facility was built to investigate the feasibility of the ozonation for sludge reduction and recycle. The system consists of three main parts; advanced wastewater treatment, sludge ozone treatment and belt press dewatering. Ozonation of wastewater sludge resulted in mass reduction by mineralization as well as volume reduction by improvement of dewatering characteristics. The supernatant of the ozonated sludge, consisting of solubilized organics and micro-particles, proved to be an effective carbon source for denitrification. A simple economic assessment reveals that the ozonation process can be more economical than incineration for sludge treatment and disposal at small- and medium-sized wastewater treatment plants.


2012 ◽  
Vol 65 (8) ◽  
pp. 1428-1434 ◽  
Author(s):  
L. Vacková ◽  
R. Stloukal ◽  
J. Wanner

Large wastewater treatment plants have to deal not only with the influent wastewater, but also with the highly concentrated reject water coming from anaerobic digestion. The aim of this work was to verify the suitability of using encapsulated nitrifiers in polyvinyl alcohol carrier (so called Lentikats Biocatalyst) at temperatures between 5 and 30 °C. For laboratory nitrification batch tests synthetic wastewater with ammonia nitrogen (Namon) concentration 10–800 mg L−1 was used. The system has been proved to operate at the temperature of 10 °C, but not at 5 °C. It was found that the highest specific nitrification rates were observed at 30 °C and with ammonia nitrogen concentrations above 250 mg L−1, which means that separate treatment of reject water by using encapsulated biomass seems to be an effective tool for wastewater treatment plant optimization.


Author(s):  
Yongkui Yang ◽  
Longfei Wang ◽  
Feng Xiang ◽  
Lin Zhao ◽  
Zhi Qiao

Controlling wastewater pollution from centralized industrial zones is important for reducing overall water pollution. Microbial community structure and diversity can adversely affect wastewater treatment plant (WWTP) performance and stability. Therefore, we studied microbial structure, diversity, and metabolic functions in WWTPs that treat industrial or municipal wastewater. Sludge microbial community diversity and richness were the lowest for the industrial WWTPs, indicating that industrial influents inhibited bacterial growth. The sludge of industrial WWTP had low Nitrospira populations, indicating that influent composition affected nitrification and denitrification. The sludge of industrial WWTPs had high metabolic functions associated with xenobiotic and amino acid metabolism. Furthermore, bacterial richness was positively correlated with conventional pollutants (e.g., carbon, nitrogen, and phosphorus), but negatively correlated with total dissolved solids. This study was expected to provide a more comprehensive understanding of activated sludge microbial communities in full-scale industrial and municipal WWTPs.


2008 ◽  
Vol 57 (8) ◽  
pp. 1183-1189 ◽  
Author(s):  
Naoyuki Funamizu ◽  
Mikako Takenaka ◽  
Junkyu Han ◽  
Hiroko Isoda

In this study we applied bioassay using Chinese hamster ovary (CHO) cells with a heat shock protein (HSP) 47 promoter to the effluent of the wastewater treatment plants in Sapporo and we observed the statistically significant HSP production. This implied the effluent contained some organic matter which can stress the CHO cells. To investigate the possible causes of the toxicity of the effluent, we applied the assay to the rejected water from the sludge treatment plant, the mixtures of sewage and rejected water. The evolution of HSP production during the aerobic decay process and thickening process of sludge was also examined. These assay results showed that dissolved microbial products generated and/or released from activated sludge during its decay process in the aeration tank and during thickening and dewatering process in the sludge treatment train contributed to develop HSP production. The proteomics analysis was also applied to the effluent and detected the production of elongation factor 1β. This result implies that the effluent from wastewater treatment plants may cause changes in cell proteins involved in allergic reaction.


2006 ◽  
Vol 54 (9) ◽  
pp. 1-8 ◽  
Author(s):  
J. Wiese ◽  
M. Haeck

In recent years manure-based biogas plants (MBBP) have won more and more importance, because of the numerous ecological advantages. The processes are similar to processes, which have been well known for many decades in anaerobic wastewater/sludge treatment. As a result of technical progress and permanently rising prices for non-renewable energy, MBBPs have become more and more economically reasonable. Because of the economies of scale law more and more larger MBBPs are being built (250–2000 kWel). With regard to investment costs, reactor volumes and complexity etc., these (centralized) plants are comparable with small wastewater treatment plants (WWTP). Consequently, as actually in the case of the small WWTPs a rising use of instrumentation, control and automation (ICA) for larger MBBPs can be observed.


2011 ◽  
Vol 64 (6) ◽  
pp. 1195-1201 ◽  
Author(s):  
Bjorn Rusten ◽  
Ashish K. Sahu

Proof-of-concept has been demonstrated for a process that will utilize nutrients from sludge liquor, natural light, and CO2 from biogas to grow microalgae at wastewater treatment plants. This process will reduce the impact of returning side-streams to the head of the plant. The produced algae will be fed to anaerobic digesters for increased biogas production. Dewatering of anaerobically digested sludge in centrifuges produces reject water with extremely low transmittance of light. A pre-treatment procedure was developed that improved light transmittance for reject water from the FREVAR, Norway, wastewater treatment plant from 0.1% T to 77% T (670 nm, 1 cm path). Chlorella sp. microalgae were found to be suitable for growth in this pre-treated reject water. Typical nitrogen removal was 80–90 g N/kg TSS of produced microalgae. The microalgae were successfully harvested by chemically assisted flocculation followed by straining through a 33 μm sieve cloth, achieving up to 99% recovery. Harvested algae were anaerobically co-digested with wastewater sludge. The specific methane gas production (mL CH4/g VS fed) for the algae varied from less than 65% to 90% of the specific methane gas production for the wastewater sludge, depending on digester temperature, retention time and pre-treatment of the algae biomass.


Study on sampling sludge from 04 industrial parks in Binh Duong province such as My Phuoc, Dong An, Viet Huong 1, Song Than 2 to analyze the pollution criteria to assess the pollution possibility of industrial waste sludge. The research results show that: at present, the total volume of sludge generated today in the industrial park fluctuates about 4,450 – 6,255 kg/day, equivalent to dry sludge volume is 1,035.725 – 1,532.11 kg/day. The estimated volume of dry sludge generated from industrial parks in the future from 2019 to 2020 ranges from 30,023 to 31,396 kg/day. Most sludge from 04 wastewater treatment plants hadn’t heavy metals (Hg, Pb, Cu, Ni, Cr, Zn, Cd), especially Dong An Industrial park Treatment plant had Zn, value 49.7 – 49.9 mg/l. The sludge from the wastewater treatment plants of 04 industrial parks had amount of helminth eggs that exceeds the USEPA's regulations on pathogens (type A sludge).


2006 ◽  
Vol 54 (8) ◽  
pp. 93-100 ◽  
Author(s):  
E.I.P. Volcke ◽  
K.V. Gernaey ◽  
D. Vrecko ◽  
U. Jeppsson ◽  
M.C.M. van Loosdrecht ◽  
...  

In wastewater treatment plants (WWTPs) equipped with sludge digestion and dewatering systems, the reject water originating from these facilities contributes significantly to the nitrogen load of the activated sludge tanks, to which it is typically recycled. In this paper, the impact of reject water streams on the performance of a WWTP is assessed in a simulation study, using the Benchmark Simulation Model no. 2 (BSM2), that includes the processes describing sludge treatment and in this way allows for plant-wide evaluation. Comparison of performance of a WWTP without reject water with a WWTP where reject water is recycled to the primary clarifier, i.e. the BSM2 plant, shows that the ammonium load of the influent to the primary clarifier is 28% higher in the case of reject water recycling. This results in violation of the effluent total nitrogen limit. In order to relieve the main wastewater treatment plant, reject water treatment with a combined SHARON-Anammox process seems a promising option. The simulation results indicate that significant improvements of the effluent quality of the main wastewater treatment plant can be realized. An economic evaluation of the different scenarios is performed using an Operating Cost Index (OCI).


Wastewater treatment leads to a significant production of about 150 to 200 kg of sludge per population equivalent (P.E) per year, with a humidity level higher than 90%. The treatment and discharge of this sludge involves high costs for wastewater treatment plants (WWTPs), which can amount to up to 60% of their total operating cost. The environmental and public health aspect should also be carefully considered during evacuation as sludge may contain harmful elements. Currently, several treatment, valorization and disposal methods are possible for sludge. In order to respect the various constraints on the possibilities of discharging sludge and to minimize its cost, a reasonable approach must be followed to establish an optimal management path according to the WWTP situation. The objective of this work is to develop a methodology for optimizing sludge treatment, valorization and disposal methods for a given WWTP. This method is based on operational research technique. The methodology follows the following six steps: description of the existing situation, identification of possible treatment, valorization and disposal methods for the WWTP and development of a decision tree specific to the WWTP, mathematical formulation and assumptions, mathematical resolution and sensitivity analysis, validation of the solution and application of the solution. After the application of this methodology, a decision support tool is developed to define the optimal method(s) for sludge management in the WWTP. According to the example of the application of this methodology on sludge management of the WWTP of Marrakech (Morocco), the optimal solution, with respect to the data used and keeping the installations in place, is the application of agricultural spreading after the sludge treatments which are: thickening, anaerobic digestion, mechanical dehydration and solar drying. On a 20-year operation, an average gain of about €10 (110 DHs) per ton of dry solid (DS) incoming is generated.


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