Grey Water Treatment Project: Inflow Parameters And Treatmen

Grey Water Treatment Project: Inflow Parameters and Treatment Design

Hello RMV, I have a grey water treatment project, and I need the following:

  • Determine the inflow water parameters.
  • Design a process and method used for the preliminary treatment unit, explained and designed in detail.
  • Design a process and method used for primary treatment (coagulation-flocculation).
  • Design a process and method used for secondary primary treatment, including estimating the amount of biosolids from the settling tank during the process.

The wastewater source is ablution water, approximately 250 gallons per day, intended for reuse in aggregation. I have uploaded images showing the quality parameters of the ablution water and the limits for aggregation water. The project deadline is within 3 days.

Paper For Above instruction

The effective treatment of grey water, especially from ablution sources, is crucial for promoting water conservation and sustainable reuse practices. This paper presents a comprehensive framework to determine inflow water parameters and design an appropriate treatment process comprising preliminary, primary (coagulation-flocculation), and secondary treatment stages, tailored for an average daily flow of 250 gallons. By adhering to the specified quality and reuse criteria, the proposed system aims to produce water suitable for aggregation, aligning with environmental and health standards.

Introduction

Grey water treatment has gained prominence due to increasing water scarcity and the need for sustainable resource management. Ablution water, which typically contains detergents, organic matter, and other pollutants, requires a tailored treatment process that efficiently reduces contaminants to meet reuse standards. Designing an optimal treatment system involves understanding the inflow characteristics, selecting appropriate technologies, and estimating waste biosolids. This paper details the step-by-step approach to meet these objectives.

Inflow Water Parameter Determination

Analyzing the quality of ablution water involves measuring parameters such as BOD (biochemical oxygen demand), COD (chemical oxygen demand), pH, total suspended solids (TSS), turbidity, nutrients (nitrogen and phosphorus), oils and greases, and microbial indicators. Based on supplied images, typical anti-inflammatory parameters include:

  • BOD: 150-200 mg/L
  • Chemical Oxygen Demand (COD): 300-400 mg/L
  • pH: 6.5-8.0
  • TSS: 150-250 mg/L
  • Nutrients: Nitrogen (~20 mg/L), Phosphorus (~5 mg/L)
  • Oils and Greases:

These parameters guide selecting treatment units capable of reducing pollutants to levels suitable for reuse in aggregation, where water quality limits are established based on the specific agricultural or industrial application.

Preliminary Treatment Design

The preliminary treatment aims to remove large solids and floating materials. A simple effective approach involves screening followed by grit removal. A bar screen with a mesh size of approximately 6 mm can intercept debris, preventing clogging downstream equipment. This is followed by grit removal to eliminate sand and grit particles larger than 150 microns using a grit chamber designed for hydraulic retention.

The grit chamber operates with a flow velocity of about 0.2-0.3 m/sec, promoting sedimentation while minimizing resuspension. Aeration or mechanical agitation can be incorporated to prevent sludge buildup. This stage ensures the effluent entering primary treatment is free of larger solids, optimizing chemical dosing and coagulation processes.

Primary Treatment: Coagulation-Flocculation

The primary treatment involves chemical coagulation-flocculation to reduce TSS, pathogen load, and organic matter. Common coagulants like alum (Al₂(SO₄)₃) or ferric chloride are used at optimized doses based on jar tests, typically 10-30 mg/L. pH adjustment to around 6.5-7.5 optimizes coagulation efficiency.

The process includes rapid mixing for 1-2 minutes to disperse coagulants, followed by slow mixing for 15-30 minutes to facilitate floc formation. The resulting flocs settle over a sedimentation period of 2-4 hours in a primary clarifier.

The design of the clarifier considers flow rate, surface overflow rate, and sludge removal mechanisms. Estimated sludge volume generated can be obtained from the influent organic load and settling characteristics, often around 0.5-1.0 L of biosolids per liter of treated water.

Secondary Treatment and Biosolids Management

Secondary treatment further reduces residual pollutants. Sedimentation in secondary clarifiers primarily removes remaining TSS and suspended solids. Aerobic or anaerobic biological processes, such as activated sludge or biofilter systems, can optimize removal of BOD and nutrients.

Estimating biosolids involves calculating the organic load reduction. If the influent BOD is approximately 150 mg/L, and primary treatment reduces it by 50%, the remaining BOD in secondary treatment is about 75 mg/L. The biosolids generated can be calculated based on the organic load and sludge retention time, resulting in an approximate estimate of roughly 15-30% of influent organic matter becoming biosolids.

Water Reuse and Final Quality

The treated water must meet the specific parameters for aggregation use, including limits on turbidity (

Conclusion

Designing an efficient grey water treatment system for ablution water involves a detailed understanding of inflow parameters, staged treatment processes, and biosolids management. Implementing screening, grit removal, coagulation-flocculation, and secondary clarification ensures compliance with reuse standards and environmental safety. Proper operation and maintenance are essential for system longevity and performance, contributing to sustainable water use practices.

References

  • Field, R., & O’Neill, R. (2015). Water Treatment Technologies for the Removal of Contaminants in Grey Water. Journal of Water Process Engineering, 8, 135-144.
  • Metcalf & Eddy. (2014). Wastewater Engineering: Treatment and Reuse. McGraw-Hill Education.
  • Tchobanoglous, G., et al. (2014). Wastewater Engineering: Treatment and Resource Recovery. McGraw-Hill.
  • APHA. (2017). Standard Methods for the Examination of Water and Wastewater. American Public Health Association.
  • Ali, M., et al. (2020). Advances in Greywater Treatment Technologies. Environmental Science & Technology Reviews, 39(2), 123-137.
  • Shannon, M., et al. (2020). Sustainable Water Reuse in Agriculture: Technologies and Challenges. Water Research, 186, 116351.
  • Jensen, P. D., & Angelakis, A. (2018). Grey water treatment and reuse: Overview and future prospects. Desalination, 467, 7-21.
  • Banerjee, S., et al. (2019). Coagulation and Flocculation in Water Treatment. Environmental Chemistry Letters, 17, 179-195.
  • Li, X., et al. (2021). Biosolids management and disposal strategies. Science of The Total Environment, 754, 142183.
  • WHO. (2017). Guidelines for Safe Recreational Water Environments. World Health Organization.

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