Testing of the methodology for the estimation of the wastewater generation in the sector industry Statistical Office of Estonia Environment and Sustainable Development Statistics Section

Background The Eurostat/OECD Joint Questionnaire on the State of Environment, part Water asks data for wastewater generation and loads of pollutants (BOD, suspended solids, N-tot, P-tot) in discharged wastewater by economic categories. Up to present there was no data available on the wastewater generation by the sector industry.

Tasks Find the wastewater volume and loads by selected industries by NACE codes Testing of existing methods for estimating wastewater volumes and pollutant loads

Sources 1.Report and database of Estonian Environment Information center “Water management” 2. Survey of Statistical Office “Water management” 3. Database of wastewater treatment plants 4. M.Zessner, S.Lindtner "A method for load estimations of municipal point source pollution"

Statistical Office additional survey Survey population All industrial enterprises which have not produced environmental report but have produced the PRODCOM statistical report were surveyed related to water management AIMS Reach the full coverage of industrial sector on NACE 2digit level on water use (by purpose types) and wastewater generation Figure out the quantity relationship between the water use and wastewater generation on NACE 2 digit level

Survey population of Statistical Office survey

Enterprises were handled in two categories: THE REAL DATA ON WASTEWATER GENRATION WERE USED for the enterprises who presented data on water use and wastewater generation THE DATA WERE ESTIMATED ON THE BASES OF NET SALES for the enterprises who did not present data on water use and wastewater generation

Wasteater factor: Amount of generated wastewater, m3 _____________ Net sales, kronos Estimation of the missing data in Statistical Office survey

Principles for the estimation of generated wastewater quantities by economic activities (NACE group) Statistical Office survey results Estimations of wastewater quantities on the bases of EEIC database on water use Estimations for missing wastewater quantities based on monetary factor Waste water quantities For each economic activity group: wastewater quantities by types

Total wastewater generated...as the sums of the three enterprise categorie s data

“Waste water generated” as the sum of the discharges of three enterprise categories EMTAK m3 ETC- grey Estimations-white Stat office survey-black

ETC- grey, estimation-white, Stat office survey-black “Waste water generated”, the share of discharges of three enterprise categories in total of the economic activity

The estimation of pollution

The estimation of pollution (P, N, BOD, suspended solids) in industrial wastewater was performed in two locations of the wastewater flow: Generation Discharge to environment...for each economic activity group, NACE 2 digit level...

Allocation to economic activities of the pollution loads of wastewater discharged to the environment was performed using average loads Total pollution quantities in waste water Cooling water pollution load Industrial and everyday waste water pollution load Average load directed to environment: BHT7: 18,6 total-N: 35, 0 total-P: 2,1 suspended solids: 27,9 Average load directed to environment: BHT7: 3,8 g/m3 total-N: 2,4 total-P: 0,1 suspended solids: 13,2...for each economic activity group... Presumtion: all NACE branches were treated similarly in sense of pollution concentration

Pollution load of discharged wastewater

Calculation of generated by indstry sector wastewater loadings, before treatment Wastewater treatment plants inflow monitoring data were used for the calculations of the generated wastewater pollution parameters

Presumption: One inhabitat consumes daily in average 127 litres water and generates the same amount of wastewater (expert opinion) Wastewater treatment plants were devided 1) URBAN 2) Other (industrial included)

Source data

Urban treatment plants Other treatment plants Industrial water Inhabitants water Pollution concentration BOD 318,0 g/m3 Susp sol 384,9 g/m3 Tot N 61,9 g/m3 Tot P 12,9 g/m3 Pollution concentration BOD 301,3 g/m3 Susp sol 262,8 g/m3 Tot N 61,4 g/m3 Tot P 12,7 g/m3 For industrial and inhabitants wastewater the summary quantities and average pollutants concentrations were found

For the allocation to the NACE categories the pollution quantities of the generated wastewater, the following presumptions were made: “Wastewater originating from industry” pollution loadings are distributed proportionally to the generated wastewater quantities. “Everyday wastewater originating from industry” pollution loadings concentrations are considered to be equal to the inhabitants wastewater parameters

Wastewater generated by economic activities, quantities, BOD, susp, N, P

Calculations on the bases of M.Zessner, S.Lindtner "A method for load estimations of municipal point source pollution”. Pollution generated by industry was found as difference between total pollution and pollution generated by inhabitants Pollution generated by inhabitants was calculated using parametres found from literature The comparison was made between the estimations based on wastewater treatment plants data and the other ones based on parametres found from literature

Parameters: M.Zessner, S.Lindtner "A method for load estimations of municipal point source pollution” One inhabitat is daily generating in average: 60g of BOD 5 11g of N-tot 1,6g of P-tot Presumption BHT5 = BHT7

Comparison of estimations on pollution quantities and loads by two methods

Differences are bigger in activities there the share of the use of everyday water is bigger Comparison of pollution estimations on NACE 2 digit level

Testing of the methodology for the estimation of the generated (inflow to treatment plants) wastewater pollution (N and P) The pollutant quantities calculated according to “M.Zessner, S.Lindtner “A method for load estimations of municipal point source pollution” ” were compared to monitoring data of 138 urban wastewater treatment plants

For the comparison the data of the 138 urban waste water treatment plants were used for which all necessary parameters existed in database: BOD of inflow N- tot of inflow P-tot of inflow Quantity of wastewater treated Number of connected population Designed capacity

Avarage characteristics of wastewater stemming from households: 11g N / pe.d 1,6g P / pe.d Avarage characteristics of wastewater stemming from industry: 6,5g N / pe.d 1,3g P / pe.d Avarage characteristics of inflow to wastewater treatment palnts: 8,8g N / pe.d 1,5g P / pe.d At least data of 20 wastewater treatment plants are needed pe.d = 60g BOD daily Wasteater treatment plants work at 63% of designed capacity The relation between N and P in inflow is 6:1 Our presumption: BOD 5=BOD7 Source parametres used in calculations

In M.Zessner, S.Lindtner “A method for load estimations of municipal point source pollution” 5 possibilities is given for calculation of N-tot and P-tot load in influents. Assumption 1 Only the design capacity of a treatment plant is known Assumption 2 Design capacity and connected inhabitants are known Assumption 3 The BOD-influent load is known from measurements Assumption 4 The N-tot or P-tot influent loads are known from measurements Assumption 5 The BOD-influent load and the connected inhabitants are known

Comparisons of calculated nitrogen and phosphorus quantities with monitoring data

Sources of errors: 1. BOD7 is used in Estonia (BOD5 in Austria) 2. The nitrogen and phosphorus loads relation in Estonian wastewater is 5:1 (6:1 in Austria) 3. In Estonia the population equivalent (pe) is less than The designed capacity of wastewater treatment plants and the real capacity could be very different

Further steps: Second meeting of the steering group Recalculations based on BOD 5 (and the Estonian people equivalent of BOD) Recalculations of N and P loads in generated wasteater by economic activities Writing of the final report