membrane-system-design

name	membrane-system-design
description	Expert skill for membrane filtration and separation system design including process selection, flux calculations, fouling analysis, and concentrate management.
allowed-tools	Read, Grep, Write, Bash, Edit, Glob
category	Water and Wastewater Treatment
backlog-id	SK-003
metadata	{"author":"babysitter-sdk","version":"1.0.0"}
graph	{"domains":["domain:environmental-engineering"],"skillAreas":["skill-area:data-analysis","skill-area:statistical-analysis","skill-area:geospatial-data-analysis"],"workflows":["workflow:experiment-design"],"roles":["role:research-engineer"]}

Membrane System Design Skill

Membrane filtration and separation system design for water and wastewater treatment applications.

Purpose

This skill provides comprehensive capabilities for designing membrane treatment systems, including process selection, flux and recovery calculations, fouling analysis, pretreatment requirements, and concentrate management planning.

Capabilities

Membrane Process Selection

• Microfiltration (MF) applications
• Ultrafiltration (UF) applications
• Nanofiltration (NF) applications
• Reverse Osmosis (RO) applications
• Process selection criteria and decision matrix
• Hybrid system configurations

Flux and Recovery Rate Calculations

• Design flux determination
• Temperature correction factors
• Recovery rate optimization
• Concentration polarization effects
• Osmotic pressure calculations
• Permeate quality estimation

Pretreatment Requirements Assessment

• Feed water characterization
• Silt Density Index (SDI) analysis
• Modified Fouling Index (MFI) calculation
• Pretreatment technology selection
• Chemical conditioning requirements

Fouling Analysis and Mitigation

• Fouling mechanism identification
• Biofouling assessment
• Scaling potential analysis
• Colloidal fouling evaluation
• Organic fouling characterization
• Mitigation strategy development

Concentrate Management Planning

• Concentrate characterization
• Disposal options evaluation
• Zero Liquid Discharge (ZLD) considerations
• Brine concentration technologies
• Regulatory compliance for disposal

CIP System Design

• Clean-in-Place system configuration
• Chemical cleaning protocols
• Cleaning frequency optimization
• Chemical compatibility assessment
• Cleaning effectiveness monitoring

Energy Recovery Device Selection

• Pressure exchanger sizing
• Turbocharger systems
• Energy recovery efficiency
• Economic analysis
• System integration

Membrane Pilot Testing Protocols

• Pilot system design
• Test protocol development
• Data collection requirements
• Performance metrics
• Scale-up considerations

Prerequisites

Installation

pip install numpy scipy pandas matplotlib

Optional Dependencies

# For optimization
pip install scipy pymoo

# For visualization
pip install plotly seaborn

Usage Patterns

Membrane System Sizing

import numpy as np
from dataclasses import dataclass
from typing import Dict, List, Optional

@dataclass
class FeedWaterQuality:
    """Feed water quality parameters"""
    tds_mg_l: float
    temperature_c: float
    ph: float
    tss_mg_l: float
    toc_mg_l: float
    hardness_mg_l: float = 0  # as CaCO3
    silica_mg_l: float = 0
    sdi: float = 0  # Silt Density Index

@dataclass
class MembraneElement:
    """Membrane element specifications"""
    manufacturer: str
    model: str
    area_m2: float
    permeability_lmh_bar: float  # L/m2/hr/bar
    salt_rejection: float  # decimal
    max_recovery: float  # decimal
    min_concentrate_flow_m3_hr: float

class ROSystemDesign:
    """Reverse Osmosis system design"""

    def __init__(self, feed: FeedWaterQuality, element: MembraneElement):
        self.feed = feed
        self.element = element

     () -> :
        
        
        
        
          * (tds_mg_l / ) * ( + .feed.temperature_c) / 

     () -> :
        
        
        T_kelvin =  + .feed.temperature_c
         np.exp( * (/ - /T_kelvin))

     () -> :
        
        
        avg_concentration_factor =  / ( - recovery/)
        avg_tds = .feed.tds_mg_l * avg_concentration_factor
        pi_avg = .osmotic_pressure(avg_tds)

        
        ndp = feed_pressure_bar - pi_avg -   

        
        tcf = .temperature_correction_factor()
        flux = .element.permeability_lmh_bar * ndp * tcf

         flux

     () -> :
        

        
        flux = .calculate_flux(feed_pressure_bar, target_recovery)

        
        permeate_flow = feed_flow_m3_hr * target_recovery

        
        required_area = (permeate_flow * ) / flux  

        
        num_elements = np.ceil(required_area / .element.area_m2)

        
        elements_per_vessel = 
        num_vessels = np.ceil(num_elements / elements_per_vessel)
        actual_elements = num_vessels * elements_per_vessel

        
        concentrate_flow = feed_flow_m3_hr * ( - target_recovery)
        concentrate_tds = .feed.tds_mg_l / ( - target_recovery)

        
        avg_passage =  - .element.salt_rejection
        permeate_tds = .feed.tds_mg_l * avg_passage * ( + target_recovery)

        
        pump_efficiency = 
        sec_kwh_m3 = (feed_pressure_bar * ) / ( * pump_efficiency * target_recovery)

         {
            : flux,
            : required_area,
            : (num_vessels),
            : elements_per_vessel,
            : (actual_elements),
            : permeate_flow,
            : concentrate_flow,
            : permeate_tds,
            : concentrate_tds,
            : sec_kwh_m3
        }


feed = FeedWaterQuality(
    tds_mg_l=,
    temperature_c=,
    ph=,
    tss_mg_l=,
    toc_mg_l=,
    sdi=
)

element = MembraneElement(
    manufacturer=,
    model=,
    area_m2=,
    permeability_lmh_bar=,
    salt_rejection=,
    max_recovery=,
    min_concentrate_flow_m3_hr=
)

ro_system = ROSystemDesign(feed, element)
design = ro_system.design_system(
    feed_flow_m3_hr=,
    target_recovery=,
    feed_pressure_bar=
)

()
()
()
()
()

Scaling Potential Analysis

class ScalingAnalysis:
    """Membrane scaling potential analysis"""

    # Solubility product constants at 25C
    Ksp = {
        'CaCO3': 3.3e-9,
        'CaSO4': 4.9e-5,
        'BaSO4': 1.1e-10,
        'SrSO4': 3.4e-7,
        'SiO2': 120  # mg/L saturation
    }

    def __init__(self, water_quality: Dict):
        self.wq = water_quality

    def langelier_saturation_index(self, temperature_c: float,
                                   tds_mg_l: float) -> float:
        """Calculate Langelier Saturation Index for CaCO3"""
        pH = self.wq.get('pH', 7.5)
        Ca = self.wq.get('Ca_mg_l', 100)
        alkalinity = self.wq.get('alkalinity_mg_l', 100)

        # pHs calculation (simplified)
        pCa = -np.log10(Ca / 40080)  # Convert to mol/L
        pAlk = -np.log10(alkalinity / 50040)

        # Temperature and TDS corrections
        A = (np.log10(tds_mg_l) - 1) / 10
        B = -13.12 * np.log10(temperature_c + 273) + 34.55
        C = np.log10(Ca / ) - 
        D = np.log10(alkalinity / )

        pHs = ( + A + B) - C - D
        lsi = pH - pHs

         lsi

     () -> :
        
        pH = .wq.get(, )
        Ca = .wq.get(, )
        alkalinity = .wq.get(, )

        
        K =   

        pCa = -np.log10(Ca /  * )  
        pAlk = -np.log10(alkalinity /  * )
        pK = -np.log10(K)

        pHs = pK + pCa + pAlk
        sdi = pH - pHs

         sdi

     () -> :
        
        Ca = .wq.get(, )
        SO4 = .wq.get(, )

        
        cf =  / ( - recovery)

        
        Ca_conc = (Ca / ) * cf  
        SO4_conc = (SO4 / ) * cf  
        ip = Ca_conc * SO4_conc

        
        sr = ip / .Ksp[]

         sr

     () -> :
        
        SiO2 = .wq.get(, )

        
        cf =  / ( - recovery)
        SiO2_conc = SiO2 * cf

        
        saturation_limit = .Ksp[] + (temperature_c - ) * 

         SiO2_conc / saturation_limit

     () -> :
        
        tds_concentrate = .wq.get(, ) / ( - recovery)

        results = {
            : recovery,
            :  / ( - recovery),
            : tds_concentrate,
            : .langelier_saturation_index(temperature_c, tds_concentrate),
            : .calcium_sulfate_saturation(recovery),
            : .silica_saturation(recovery, temperature_c)
        }

        
        results[] =   results[] >   \
                                 results[] >   
        results[] =   results[] >   \
                                 results[] >   
        results[] =   results[] >   \
                                  results[] >   

         results


water_quality = {
    : ,
    : ,
    : ,
    : ,
    : ,
    : 
}

scaling = ScalingAnalysis(water_quality)
results = scaling.analyze_scaling_potential(recovery=, temperature_c=)

()
()
()
()

CIP Protocol Development

class CIPProtocol:
    """Clean-in-Place protocol development"""

    def __init__(self, membrane_type: str = 'polyamide'):
        self.membrane_type = membrane_type

        # Chemical compatibility
        self.ph_limits = {
            'polyamide': (2, 11),
            'cellulose_acetate': (4, 7),
            'polysulfone': (1, 13)
        }

        self.temperature_limit = {
            'polyamide': 45,
            'cellulose_acetate': 35,
            'polysulfone': 50
        }

    def recommend_cleaning_chemicals(self, fouling_type: str) -> List[Dict]:
        """Recommend cleaning chemicals based on fouling type"""
        recommendations = {
            'biofouling': [
                {'chemical': 'NaOH', 'concentration': '0.1%', 'ph': 12, 'temperature_c': 35},
                {'chemical': 'Biocide', 'concentration': 'Per manufacturer', 'ph': , : }
            ],
            : [
                {: , : , : , : },
                {: , : , : , : }
            ],
            : [
                {: , : , : , : },
                {: , : , : , : }
            ],
            : [
                {: , : , : , : },
                {: , : , : , : }
            ],
            : [
                {: , : , : , : }
            ]
        }

         recommendations.get(fouling_type, [])

     () -> :
        
        ph_min, ph_max = .ph_limits.get(.membrane_type, (, ))
        temp_max = .temperature_limit.get(.membrane_type, )

        procedure = {
            : .membrane_type,
            : ,
            : temp_max,
            : system_volume_m3,
            : []
        }

        
        procedure[].append({
            : ,
            : ,
            : ,
            : ,
            : 
        })

        
        step_num = 
         fouling  fouling_types:
            chemicals = .recommend_cleaning_chemicals(fouling)
             chem  chemicals:
                 chem[] <= temp_max  ph_min <= chem[] <= ph_max:
                    procedure[].append({
                        : step_num,
                        : ,
                        : chem[],
                        : chem[],
                        : chem[],
                        : ,
                        : ,
                        : ,
                        : 
                    })
                    step_num += 

        
        procedure[].append({
            : step_num,
            : ,
            : ,
            : 
        })

         procedure


cip = CIPProtocol(membrane_type=)
procedure = cip.generate_cip_procedure(
    fouling_types=[, ],
    system_volume_m3=
)

()
 step  procedure[]:
    ()

Usage Guidelines

When to Use This Skill

• Membrane system design and specification
• Pilot testing protocol development
• Fouling diagnosis and mitigation
• System optimization and troubleshooting
• Pretreatment system design

Best Practices

1. Characterize feed water thoroughly before design
2. Use pilot testing for critical applications
3. Design for maintainability including CIP access
4. Monitor membrane performance trends regularly
5. Maintain chemical dosing records for troubleshooting
6. Plan for concentrate management early in design

Process Integration

• WW-003: Membrane Treatment System Design (all phases)
• WW-005: Water Reuse System Implementation (membrane phases)

Dependencies

• numpy: Numerical calculations
• scipy: Optimization routines

References

• AWWA M46 "Reverse Osmosis and Nanofiltration"
• Dow Water & Process Solutions Technical Manual
• Hydranautics Technical Application Bulletins