Practical implementations

Pilot plant units drinking water for rural areas of Lao PDR

 

Targets of pilot plants
  • Examine and adapt test arsenic removal based on FerroSorpPlus in rural areas of Lao PDR
  • Test of  arsenic removal linked with water disinfection

 

Requirements of construction and operation of pilot plants
  • Simple construction based on standard construction units
  • Simple operation and maintenance
  • Reasonable investment and specific costs of drinking water
  • Without respectively with low consumption of electric energy

 

FerroSorp® Plus – multivalent adsorbent

Sources  and properties of FerroSorp PLUS
  • Granulare amorph iron-oxy-hydroxid based  on geological sources
  • Produced in Germany by HeGo BioTec GmbH
  • The raw material based on by-products of de-ironing of ground water

FerroSorp® Plus

 

Removal performance  of FerroSorp
  • Remove arsenic As(III) and As(V)  8 up to 12 g/kg
  • Heavy metals like cadmium, lead, cupper, cink  6 up to 8   g/kg
  • Hydrogen sulphide,
Economical numbers of FerroSorp
  • Sales price: about  2.2 up to 2.6 $/kg Compared with comparable synthetic GFH products: 6.6 up to 8.8 $/kg [source: EPA 2012]
  • Specific costs of adsorbent to decrease arsenic e.g.  from 150 µg/l down to 10 µg/l 2.5 up to 4 $ct / m³ drinking water  (200 up to 300 KIP/m³)

 

Fe(OH)3 + H3AsO4 → FeAsO4 + 3 H2O

2 Fe(OH)3 + 3 H2S → 2 Fe2S3 + 6 H2O

 

FerroSorp® Plus1

Dimensioning filter column FerroSorp® Plus

Dimensioning basis parameter
  • Flow rate velocity                                     5 – 20   m/h
  • Max. backwashing rate                            30  m/h
  • Min. Emty bed contact time (EBCT)         5  min
  • Max. operating Temperature                    + 60  oC
  • Max. tolerable head loss                          0.5  bar
  • Max. bed depth                                        5  m
Requirement  of water quality
  • pH    5 – 10
  • pH optimum (best results)                        6.5
  • DO disolved oxygen (min)                        2 mg/l
  • If below 2 mg/l: oxygen is to insert  (ejector pump, atomizer)
  • Iron content  >  1 mg/l   Iron removal reqiured  (aeration + filtration)
Competing elements of arsenic adsorbtion
  • Phosphorus
  • Silicate
Requirements of backwashing
  • Backwashing before beginning of operation:  Wash out of fine partikel of FerroSorp
  • Backwashing if filter is blocked (caused by e.g. by iron hydroxid flocs in the case that the groundwater has a higher iron content and no pri-filtration is available)

 

Dimensioning filter1Dimensioning filter

 

 

 

 

 

 

 

 

 

 

Dimensioning Arsenic filter column
Example calculation in depending on the intended  feeding rate of filter column [m³/h]

Example calculation in depending on

Consumption of FerroSorp Plus in depending on input concentration of arsenic

 

Consumption of FerroSorp Plus

Disinfection units of test plants

 

UV sterilizer have been choosen for the test plants

UV sterilizer

OWRD-B UV sterilizer series
  • performance                                0.5 – 3 m³/h
  • 100-250 V / 50-60 Hz
  • Energy consumption                    20   W
  • UV power                                     30 – 50 MJ/cm²   (enough to inactivate bacteria, viruses, protozoa, yeast and most of fungies)
  • ØEffective life time                       about   8,000  hours

UV sterilizer1

OWRD-TS UV tank sterilizer
  • Sustainable disinfection of storage tank cleaned water to prevent the re-growing of pathogens
  • Available length of UV lamps      195 – 840 mm
  • Energy consumption                   10 – 39    W
  • UV power                                    30            MJ/cm²
  • Effective life time                         about    9,000 hours

 

Basic configuration scheme of pilotplants

configuration scheme of pilotplants

 

Pilot plant   Phouvon / Attapeu

 

Pilot plant   Phouvon AttapeuPilot plant – layout

Pilot plant   B

 

Pilot plant   B

Pilot plant   Baan Nakhem / Phonehong / Vientiane

 

Pilot plant   Baan Nakhem

Pilot plant Heavy metal (Lead) Khampong District / NRO AMICA

 

Pilot plant Heavy metal (Lead) Khampong District

Results of operated test plants
  • Arsenic risk areas of LAO PDR are relatively small distributed
  • Arsenic risk contents of 10 to max 100 µg/l are relatively low compared e.g. with Cambodia or India
  • Arsenic content of tested groundwater is varying over time periods (caused by hydrogelogical / geochemical conditions)
  • Targeted arsenic removal can be achieved (< 10 µg/l)
  • Targeted disinfection can be achieved
  • DO enrichment via simple aeration is important to guarantee arsenic removal
Conclusions
  • Targets of operated test plant could be achieved
  • An economical and reasonable operation is feasible
  • Future requirements and targets of plants for rural areas
    • more focused on combined water units with less up to no consumption of electric energy
    • Combined de-ironing / arsenic removal and arsenic removal by adsorbent in case of heigher iron content of ground water

Arsenic_NDlabel_new

Drinking Water tower
A new principle modulare technological concept is created based on the project experiences and new ideas and approaches
Basic  moduls of the new concept  (without electricity)
  • Hand pump (e.g. Semi-Rotary Hand Wing Pumps Feasible performance: up to 4 m³/h; presure head: up to 20 m) or motor pumps if energy available
  • Storage tank of raw water; incl. the option of oxygen (e.g. by. Pipe injection) and function as sedimentation tank (e.g. sedimented ferric hydroxide)
  • Backwashable sandfilter (option); in case of higher iron contents
  • Backwashable Arsenic filter (option), in case of arsenic contents > 10 µg/l
  • Further filter units
  • Low pressure Ultrafiltration (UF)
  • Option:  UV tank disinfection (photovoltaic driven)
  • Option:  Disinfection with chlorine dioxide tabletts or powder

Drinking Water tower1 Drinking Water tower2Drinking Water tower3