selecting treatment technologies for small rural wastwater...

Selecting Treatment Technologies for Small Rural

Wastwater Treatment Systems within Bregalnica River

Basin Management Project in Macedonia

Darko Lefkov, Ministry of Environment and Physical Planning

Nikolcho Vangelov, Reto Bühler, Ivo Fölmli, EBP Schweiz AG

1-3 November 2017, Pristina, Kosovo

Wastewater Challenge, 1-3 November 2017, Pristina, Kosovo

Selecting Treatment Technologies for Small Rural Wastewater Treatment Systems within Bregalnica River Basin Management Project in Macedonia

Introduction – Bregalnica River Basin

Situated in Eastern Macedonia covers 17% of Macedonian territory with 15

municipalities

Many small rural settlements without wastewater treatment

Connection to regional WWTP not possible

Strong impact of untreated wastewater on regional water bodies

reducing the share of untreated wastewater



Technical requirements

Reliability: robust system, continuously operational

Effectiveness: achieve effluent standards,

remove pollutants with strong impact on water bodies

Affordability: affordable for local population, minimal overall cost

Project requirements

Single system: knowhow exchange, one operator operates several small

WWTP

Low O&M costs: low energy consumption,

no permanent local presence of operator

Short implementation time

Requirements for Technology Selection



Technologies for sWWTP

A basic WWTP consists of the following components:

• Mechanical treatment (screening, grit and grease removal, sedimentation)

• Biological treatment (primary, secondary and tertiary)

• Sludge treatment

• High investment cost

• High operation

• Complex technologies

The trickling filter, membrane bioreactor technologies and biogas reactors

were excluded from further evaluation

Exclusion of Inappropriate Technologies



Primary treatment:

Secondary treatment: Tertiary treatment:

Anerobic baffled reactor

Constructed wetland

Polishing pond Source:

Compendium of Sanitation Systems and Technologies (Eawag, 2008)

Treatment Process Selection – System ABR

Grid and grease removal

Organics and solid removal



Source: Compendium of Sanitation Systems and Technologies (Eawag, 2008)

Primary treatment:


Anaerobic pond

Facultative pond

Polishing pond

Treatment process selection – System Ponds



Primary treatment:


Septic Tank

Rotating biological

contactor (RBC)

Polishing pond

Source:

Compendium of Sanitation Systems

and Technologies (Eawag, 2008)

Source:

Compendium of Sanitation Systems and Technologies (Eawag,

2008)

Source:

Walker Process Equipment

Division of McNish Corporation

Treatment Process Selection – System RBC

Grid and grease removal

Organics removal with aerobic

degradation



RBC: - highest investment and operational costs

- operational complexity

Ponds: - investment cost highly dependent on local land prices

Ponds: - project delays due to expropriation proceduress: -

ABR: + no mosquito problem as with ponds

ABR: + less affected by cold temperatures

Evaluation of the Systems ABR, Ponds, RBC

Name of Alternative ABR Ponds RBC

Investment costs 2 3 1

Operational costs 3 3 2

Land use 2 1 3

Operational complexity 2 3 1

Sludge stabilization 3 3 3

Integrated sludge storage 3 3 3

Process stability 3 2 2

Greenhouse gas emission 1 1 2

Overall evaluation 19 19 17

1-least advantageous; 3 – most advantageous



High organic removal

Reliable even at seasonal temperature chances

Affordable for local population

Simple and economic system (no permanent surveillance required, little

energy consumption)

Anerobic baffled reactor

Constructed wetland

Polishing pond Source:

Compendium of Sanitation Systems and Technologies (Eawag, 2008)

Most Appropriate System: ABR



Treatment System Proposed by Tenders

Concept 1: Horizontal Flow Constructed Wetland (HFCW)

- primary treatment

- secondary treatment

- tertiary treatment

- sludge treatment

Concept 2: Vertical Flow Constructed Wetland (VFCW)

- primary treatment

- secondary treatment



Construction Phase

Challenges during construction

• bulding permit procedure

• groundwater

• sufficent capacity for the implementation of both projects at same time

WWTP Kucicino



Construction Phase

- defect liability period



THANK YOU FOR YOUR ATTENTION

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